doc: update NEWS and README

socket: enable nanosecond resolution RX timestamp on FreeBSD
FreeBSD allows switching the receive timestamp format to struct timespec by setting the SO_TS_CLOCK socket option to SO_TS_REALTIME after enabling SO_TIMESTAMP. If successful, the kernel then starts adding SCM_REALTIME control messages instead of SCM_TIMESTAMP.
2025-12-03 18:25:07 -05:00 · 2023-08-09 15:20:55 +02:00 · 2023-08-09 15:19:46 +02:00 · 2023-08-08 17:11:46 +02:00 · 2023-08-08 16:24:10 +02:00 · 2023-08-08 16:06:58 +02:00
232 changed files with 16340 additions and 4784 deletions
--- a/Makefile.in
+++ b/Makefile.in
@@ -33,9 +33,11 @@ CFLAGS = @CFLAGS@
 CPPFLAGS = @CPPFLAGS@
 LDFLAGS = @LDFLAGS@

+GETDATE_CFLAGS = @GETDATE_CFLAGS@
+
 EXTRA_OBJS = @EXTRA_OBJS@

-OBJS = array.o cmdparse.o conf.o local.o logging.o main.o memory.o \
+OBJS = array.o cmdparse.o conf.o local.o logging.o main.o memory.o quantiles.o \
       reference.o regress.o rtc.o samplefilt.o sched.o socket.o sources.o sourcestats.o \
       stubs.o smooth.o sys.o sys_null.o tempcomp.o util.o $(EXTRA_OBJS)

@@ -61,6 +63,8 @@ chronyd : $(OBJS)
 chronyc : $(CLI_OBJS)
 	$(CC) $(CFLAGS) -o chronyc $(CLI_OBJS) $(LDFLAGS) $(LIBS) $(EXTRA_CLI_LIBS)

+getdate.o: CFLAGS += $(GETDATE_CFLAGS)
+
 distclean : clean
 	$(MAKE) -C doc distclean
 	$(MAKE) -C test/unit distclean
@@ -134,4 +138,6 @@ Makefile : Makefile.in configure
 .deps/%.d: %.c | .deps
 	@$(CC) -MM $(CPPFLAGS) -MT '$(<:%.c=%.o) $@' $< -o $@

+ifndef NODEPS
 -include $(ALL_OBJS:%.o=.deps/%.d)
+endif
--- a/129
+++ b/129
@@ -1,3 +1,98 @@
+New in version 4.4
+==================
+
+Enhancements
+------------
+* Add support for AES-GCM-SIV with Nettle >= 3.9 to shorten NTS
+  cookies to avoid some length-specific blocking of NTP on Internet
+* Add support for multiple refclocks using extpps option on one PHC
+* Add maxpoll option to hwtimestamp directive to improve PHC tracking
+  with low packet rates
+* Add hwtstimeout directive to configure timeout for late timestamps
+* Handle late hardware transmit timestamps of NTP requests on all sockets
+* Handle mismatched 32/64-bit time_t in SOCK refclock samples
+* Improve source replacement
+* Log important changes made by command requests (chronyc)
+* Refresh address of NTP sources periodically
+* Request nanosecond kernel RX timestamping on FreeBSD
+* Set DSCP for IPv6 packets
+* Shorten NTS-KE retry interval when network is down
+* Update seccomp filter for musl
+* Warn if loading keys from file with unexpected permissions
+* Warn if source selection fails or falseticker is detected
+* Add selectopts command to modify source-specific selection options
+* Add timestamp sources to serverstats report and make its fields 64-bit
+* Add -e option to chronyc to indicate end of response
+
+New in version 4.3
+==================
+
+Enhancements
+------------
+* Add local option to refclock directive to stabilise system clock
+  with more stable free-running clock (e.g. TCXO, OCXO)
+* Add maxdelayquant option to server/pool/peer directive to replace
+  maxdelaydevratio filter with long-term quantile-based filtering
+* Add selection option to log directive
+* Allow external PPS in PHC refclock without configurable pin
+* Don't accept first interleaved response to minimise error in delay
+* Don't use arc4random on Linux to avoid server performance loss
+* Improve filter option to better handle missing NTP samples
+* Improve stability with hardware timestamping and PHC refclock
+* Update seccomp filter
+
+Bug fixes
+---------
+* Fix waitsync command to reconnect when not getting response
+
+New in version 4.2
+==================
+
+Enhancements
+------------
+* Add support for NTPv4 extension field improving synchronisation
+  stability and resolution of root delay and dispersion (experimental)
+* Add support for NTP over PTP (experimental)
+* Add support for AES-CMAC and hash functions in GnuTLS
+* Improve server interleaved mode to be more reliable and support
+  multiple clients behind NAT
+* Update seccomp filter
+* Add statistics about interleaved mode to serverstats report
+
+Bug fixes
+---------
+* Fix RTC support with 64-bit time_t on 32-bit Linux
+* Fix seccomp filter to work correctly with bind*device directives
+* Suppress kernel adjustments of system clock (dosynctodr) on illumos
+
+Other changes
+-------------
+* Switch Solaris support to illumos
+
+New in version 4.1
+==================
+
+Enhancements
+------------
+* Add support for NTS servers specified by IP address (matching
+  Subject Alternative Name in server certificate)
+* Add source-specific configuration of trusted certificates
+* Allow multiple files and directories with trusted certificates
+* Allow multiple pairs of server keys and certificates
+* Add copy option to server/pool directive
+* Increase PPS lock limit to 40% of pulse interval
+* Perform source selection immediately after loading dump files
+* Reload dump files for addresses negotiated by NTS-KE server
+* Update seccomp filter and add less restrictive level
+* Restart ongoing name resolution on online command
+
+Bug fixes
+---------
+* Fix responding to IPv4 command requests on FreeBSD
+* Fix dump files to not include uncorrected offset
+* Fix initstepslew to accept time from own NTP clients
+* Reset NTP address and port when no longer negotiated by NTS-KE server
+
 New in version 4.0
 ==================

@@ -5,25 +100,51 @@ Enhancements
 ------------
 * Add support for Network Time Security (NTS) authentication
 * Add support for AES-CMAC keys (AES128, AES256) with Nettle
-* Add support for maxsamples of 1 for faster update with -q/-Q option
+* Add authselectmode directive to control selection of unauthenticated sources
+* Add binddevice, bindacqdevice, bindcmddevice directives
+* Add confdir directive to better support fragmented configuration
+* Add sourcedir directive and "reload sources" command to support dynamic
+  NTP sources specified in files
+* Add clockprecision directive
+* Add dscp directive to set Differentiated Services Code Point (DSCP)
 * Add -L option to limit log messages by severity
-* Avoid replacing NTP sources with unreachable addresses
+* Add -p option to print whole configuration with included files
+* Add -U option to allow start under non-root user
+* Allow maxsamples to be set to 1 for faster update with -q/-Q option
+* Avoid replacing NTP sources with sources that have unreachable address
+* Improve pools to repeat name resolution to get "maxsources" sources
+* Improve source selection with trusted sources
 * Improve NTP loop test to prevent synchronisation to itself
+* Repeat iburst when NTP source is switched from offline state to online
 * Update clock synchronisation status and leap status more frequently
 * Update seccomp filter
 * Add "add pool" command
+* Add "reset sources" command to drop all measurements
+* Add authdata command to print details about NTP authentication
+* Add selectdata command to print details about source selection
 * Add -N option and sourcename command to print original names of sources
-* Add -a option to source/sourcestats command to print unresolved sources
-* Add reset command to drop all measurements
+* Add -a option to some commands to print also unresolved sources
+* Add -k, -p, -r options to clients command to select, limit, reset data

 Bug fixes
 ---------
+* Don't set interface for NTP responses to allow asymmetric routing
 * Handle RTCs that don't support interrupts
 * Respond to command requests with correct address on multihomed hosts

 Removed features
 ----------------
 * Drop support for RIPEMD keys (RMD128, RMD160, RMD256, RMD320)
+* Drop support for long (non-standard) MACs in NTPv4 packets (chrony 2.x
+  clients using non-MD5/SHA1 keys need to use option "version 3")
+* Drop support for line editing with GNU Readline
+
+New in version 3.5.1
+====================
+
+Security fixes
+--------------
+* Create new file when writing pidfile (CVE-2020-14367)

 New in version 3.5
 ==================
--- a/64
+++ b/64
@@ -28,10 +28,8 @@ What will chrony run on?
 ========================

 The software is known to work on Linux, FreeBSD, NetBSD, macOS and
-Solaris.  Closely related systems may work too.  Any other system will
-likely require a porting exercise.  You would need to start from one
-of the existing system-specific drivers and look into the quirks of
-certain system calls and the kernel on your target system.
+illumos.  Closely related systems may work too.  Any other system will
+likely require a porting exercise.

 How do I set it up?
 ===================
@@ -49,42 +47,7 @@ Frequently Asked Questions (FAQ).
 The documentation is also available on the chrony web pages, accessible
 through the URL 

-    https://chrony.tuxfamily.org/
-
-Where are new versions announced?
-=================================
-
-There is a low volume mailing list where new versions and other
-important news relating to chrony is announced.  You can join this list
-by sending mail with the subject "subscribe" to
-
-chrony-announce-request@chrony.tuxfamily.org
-
-These messages will be copied to chrony-users (see below).
-
-How can I get support for chrony?
-and where can I discuss new features, possible bugs etc?
-========================================================
-
-There are 3 mailing lists relating to chrony.  chrony-announce was
-mentioned above.  chrony-users is a users' discussion list, e.g. for
-general questions and answers about using chrony.  chrony-dev is a more
-technical list, e.g. for discussing how new features should be
-implemented, exchange of information between developers etc.  To
-subscribe to either of these lists, send a message with the subject
-"subscribe" to
-
-chrony-users-request@chrony.tuxfamily.org
-or
-chrony-dev-request@chrony.tuxfamily.org
-
-as applicable.
-
-When you are reporting a bug, please send us all the information you can.
-Unfortunately, chrony has proven to be one of those programs where it is very
-difficult to reproduce bugs in a different environment. So we may have to
-interact with you quite a lot to obtain enough extra logging and tracing to
-pin-point the problem in some cases. Please be patient and plan for this!
+    https://chrony-project.org/

 License
 =======
@@ -100,26 +63,31 @@ Miroslav Lichvar <mlichvar@redhat.com>
 Acknowledgements
 ================

-In writing the chronyd program, extensive use has been made of RFC 1305
-and RFC 5905, written by David Mills. The source code of the NTP reference
-implementation has been used to check the details of the protocol.
+In writing the chronyd program, extensive use has been made of the NTPv3 (RFC
+1305) and NTPv4 (RFC 5905) specification.  The source code of the xntpd/ntpd
+implementation written by Dennis Fergusson, Lars Mathiesen, David Mills, and
+others has been used to check the details of the protocol.

 The following people have provided patches and other major contributions
-to the program :
+to chrony:

 Lonnie Abelbeck <lonnie@abelbeck.com>
 Benny Lyne Amorsen <benny@amorsen.dk>
 Andrew Bishop <amb@gedanken.demon.co.uk>
 Vincent Blut <vincent.debian@free.fr>
 Stephan I. Boettcher <stephan@nevis1.columbia.edu>
+David Bohman <debohman@gmail.com>
 Goswin Brederlow <brederlo@informatik.uni-tuebingen.de>
 Leigh Brown <leigh@solinno.co.uk>
 Erik Bryer <ebryer@spots.ab.ca>
 Jonathan Cameron <jic23@cam.ac.uk>
 Bryan Christianson <bryan@whatroute.net>
 Juliusz Chroboczek <jch@pps.jussieu.fr>
+Dan Drown <dan-ntp@drown.org>
+Kamil Dudka <kdudka@redhat.com>
 Christian Ehrhardt <christian.ehrhardt@canonical.com>
 Paul Elliott <pelliott@io.com>
+Robert Fairley <rfairley@redhat.com>
 Stefan R. Filipek <srfilipek@gmail.com>
 Mike Fleetwood <mike@rockover.demon.co.uk>
 Alexander Gretencord <arutha@gmx.de>
@@ -129,10 +97,12 @@ Juergen Hannken-Illjes <hannken@eis.cs.tu-bs.de>
 John Hasler <john@dhh.gt.org>
 Tjalling Hattink <t.hattink@fugro.nl>
 Liam Hatton <me@liamhatton.com>
+Holger Hoffstätte <holger@applied-asynchrony.com>
 Jachym Holecek <jakym@volny.cz>
 Håkan Johansson <f96hajo@chalmers.se>
 Jim Knoble <jmknoble@pobox.com>
 Antti Jrvinen <costello@iki.fi>
+Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
 Eric Lammerts <eric@lammerts.org>
 Stefan Lucke <stefan@lucke.in-berlin.de>
 Victor Lum <viclum@vanu.com>
@@ -143,9 +113,14 @@ Victor Moroz <vim@prv.adlum.ru>
 Kalle Olavi Niemitalo  <tosi@stekt.oulu.fi>
 Frank Otto <sandwichmacher@web.de>
 Denny Page <dennypage@me.com>
+Rupesh Patel <rupatel@redhat.com>
 Chris Perl <cperl@janestreet.com>
 Gautier PHILIPPON <gautier.philippon@ensimag.grenoble-inp.fr>
 Andreas Piesk <apiesk@virbus.de>
+Mike Ryan <msr@hsilop.net>
+Baruch Siach <baruch@tkos.co.il>
+Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
+Foster Snowhill <forst@forstwoof.ru>
 Andreas Steinmetz <ast@domdv.de>
 NAKAMURA Takumi <takumi@ps.sakura.ne.jp>
 Timo Teras <timo.teras@iki.fi>
@@ -157,6 +132,7 @@ Bernhard M. Wiedemann <bwiedemann@suse.de>
 Joachim Wiedorn <ad_debian@joonet.de>
 Ralf Wildenhues <Ralf.Wildenhues@gmx.de>
 Ulrich Windl <ulrich.windl@rz.uni-regensburg.de>
+Michael Witten <mfwitten@gmail.com>
 Doug Woodward <dougw@whistler.com>
 Thomas Zajic <zlatko@zlatko.fdns.net>

--- a/array.c
+++ b/array.c
@@ -116,6 +116,21 @@ ARR_AppendElement(ARR_Instance array, void *element)
  memcpy(e, element, array->elem_size);
 }

+void
+ARR_RemoveElement(ARR_Instance array, unsigned int index)
+{
+  void *e, *l;
+
+  e = ARR_GetElement(array, index);
+  l = ARR_GetElement(array, array->used - 1);
+
+  if (e < l)
+    memmove(e, (char *)e + array->elem_size, (char *)l - (char *)e);
+  array->used--;
+
+  realloc_array(array, array->used);
+}
+
 void
 ARR_SetSize(ARR_Instance array, unsigned int size)
 {
--- a/array.h
+++ b/array.h
@@ -47,6 +47,9 @@ extern void *ARR_GetElements(ARR_Instance array);
 /* Add a new element to the end of the array */
 extern void ARR_AppendElement(ARR_Instance array, void *element);

+/* Remove element with given index */
+extern void ARR_RemoveElement(ARR_Instance array, unsigned int index);
+
 /* Set the size of the array */
 extern void ARR_SetSize(ARR_Instance array, unsigned int size);

--- a/candm.h
+++ b/candm.h
@@ -103,8 +103,14 @@
 #define REQ_ONOFFLINE 63
 #define REQ_ADD_SOURCE 64
 #define REQ_NTP_SOURCE_NAME 65
-#define REQ_RESET 66
-#define N_REQUEST_TYPES 67
+#define REQ_RESET_SOURCES 66
+#define REQ_AUTH_DATA 67
+#define REQ_CLIENT_ACCESSES_BY_INDEX3 68
+#define REQ_SELECT_DATA 69
+#define REQ_RELOAD_SOURCES 70
+#define REQ_DOFFSET2 71
+#define REQ_MODIFY_SELECTOPTS 72
+#define N_REQUEST_TYPES 73

 /* Structure used to exchange timespecs independent of time_t size */
 typedef struct {
@@ -116,6 +122,12 @@ typedef struct {
 /* This is used in tv_sec_high for 32-bit timestamps */
 #define TV_NOHIGHSEC 0x7fffffff

+/* Structure for 64-bit integers (not requiring 64-bit alignment) */
+typedef struct {
+  uint32_t high;
+  uint32_t low;
+} Integer64;
+
 /* 32-bit floating-point format consisting of 7-bit signed exponent
   and 25-bit signed coefficient without hidden bit.
   The result is calculated as: 2^(exp - 25) * coef */
@@ -264,10 +276,12 @@ typedef struct {
 #define REQ_ADDSRC_INTERLEAVED 0x80
 #define REQ_ADDSRC_BURST 0x100
 #define REQ_ADDSRC_NTS 0x200
+#define REQ_ADDSRC_COPY 0x400
+#define REQ_ADDSRC_EF_EXP1 0x800

 typedef struct {
  uint32_t type;
-  int8_t name[256];
+  uint8_t name[256];
  uint32_t port;
  int32_t minpoll;
  int32_t maxpoll;
@@ -288,7 +302,9 @@ typedef struct {
  Float offset;
  uint32_t flags;
  int32_t filter_length;
-  uint32_t reserved[3];
+  uint32_t cert_set;
+  Float max_delay_quant;
+  uint32_t reserved[1];
  int32_t EOR;
 } REQ_NTP_Source;

@@ -303,8 +319,7 @@ typedef struct {
 } REQ_Dfreq;

 typedef struct {
-  int32_t sec;
-  int32_t usec;
+  Float doffset;
  int32_t EOR;
 } REQ_Doffset;

@@ -320,6 +335,8 @@ typedef struct {
 typedef struct {
  uint32_t first_index;
  uint32_t n_clients;
+  uint32_t min_hits;
+  uint32_t reset;
  int32_t EOR;
 } REQ_ClientAccessesByIndex;

@@ -351,6 +368,25 @@ typedef struct {
  int32_t EOR;
 } REQ_NTPSourceName;

+typedef struct {
+  IPAddr ip_addr;
+  int32_t EOR;
+} REQ_AuthData;
+
+typedef struct {
+  uint32_t index;
+  int32_t EOR;
+} REQ_SelectData;
+
+/* Mask and options reuse the REQ_ADDSRC flags */
+typedef struct {
+  IPAddr address;
+  uint32_t ref_id;
+  uint32_t mask;
+  uint32_t options;
+  int32_t EOR;
+} REQ_Modify_SelectOpts;
+
 /* ================================================== */

 #define PKT_TYPE_CMD_REQUEST 1
@@ -387,9 +423,10 @@ typedef struct {
   domain socket.

   Version 6 (no authentication) : changed format of client accesses by index
-   (using new request/reply types) and manual timestamp, added new fields and
+   (two times), delta offset, and manual timestamp, added new fields and
   flags to NTP source request and report, made length of manual list constant,
-   added new commands: ntpdata, refresh, serverstats, shutdown
+   added new commands: authdata, ntpdata, onoffline, refresh, reset,
+   selectdata, serverstats, shutdown, sourcename
 */

 #define PROTO_VERSION_NUMBER 6
@@ -403,8 +440,8 @@ typedef struct {
 #define PROTO_VERSION_PADDING 6

 /* The maximum length of padding in request packet, currently
-   defined by MANUAL_LIST */
-#define MAX_PADDING_LENGTH 396
+   defined by CLIENT_ACCESSES_BY_INDEX3 */
+#define MAX_PADDING_LENGTH 484

 /* ================================================== */

@@ -453,7 +490,10 @@ typedef struct {
    REQ_ReselectDistance reselect_distance;
    REQ_SmoothTime smoothtime;
    REQ_NTPData ntp_data;
-    REQ_NTPData ntp_source_name;
+    REQ_NTPSourceName ntp_source_name;
+    REQ_AuthData auth_data;
+    REQ_SelectData select_data;
+    REQ_Modify_SelectOpts modify_select_opts;
  } data; /* Command specific parameters */

  /* Padding used to prevent traffic amplification.  It only defines the
@@ -491,7 +531,13 @@ typedef struct {
 #define RPY_MANUAL_TIMESTAMP2 17
 #define RPY_MANUAL_LIST2 18
 #define RPY_NTP_SOURCE_NAME 19
-#define N_REPLY_TYPES 20
+#define RPY_AUTH_DATA 20
+#define RPY_CLIENT_ACCESSES_BY_INDEX3 21
+#define RPY_SERVER_STATS2 22
+#define RPY_SELECT_DATA 23
+#define RPY_SERVER_STATS3 24
+#define RPY_SERVER_STATS4 25
+#define N_REPLY_TYPES 26

 /* Status codes */
 #define STT_SUCCESS 0
@@ -504,8 +550,7 @@ typedef struct {
 #define STT_BADSUBNET 7
 #define STT_ACCESSALLOWED 8
 #define STT_ACCESSDENIED 9
-/* Deprecated */
-#define STT_NOHOSTACCESS 10
+#define STT_NOHOSTACCESS 10 /* Deprecated */
 #define STT_SOURCEALREADYKNOWN 11
 #define STT_TOOMANYSOURCES 12
 #define STT_NORTC 13
@@ -530,17 +575,12 @@ typedef struct {
 #define RPY_SD_MD_PEER   1
 #define RPY_SD_MD_REF    2

-#define RPY_SD_ST_SYNC 0
-#define RPY_SD_ST_UNREACH 1
+#define RPY_SD_ST_SELECTED 0
+#define RPY_SD_ST_NONSELECTABLE 1
 #define RPY_SD_ST_FALSETICKER 2
 #define RPY_SD_ST_JITTERY 3
-#define RPY_SD_ST_CANDIDATE 4
-#define RPY_SD_ST_OUTLIER 5
-
-#define RPY_SD_FLAG_NOSELECT 0x1
-#define RPY_SD_FLAG_PREFER 0x2
-#define RPY_SD_FLAG_TRUST 0x4
-#define RPY_SD_FLAG_REQUIRE 0x8
+#define RPY_SD_ST_UNSELECTED 4
+#define RPY_SD_ST_SELECTABLE 5

 typedef struct {
  IPAddr ip_addr;
@@ -609,14 +649,17 @@ typedef struct {
 typedef struct {
  IPAddr ip;
  uint32_t ntp_hits;
+  uint32_t nke_hits;
  uint32_t cmd_hits;
  uint32_t ntp_drops;
+  uint32_t nke_drops;
  uint32_t cmd_drops;
  int8_t ntp_interval;
+  int8_t nke_interval;
  int8_t cmd_interval;
  int8_t ntp_timeout_interval;
-  int8_t pad;
  uint32_t last_ntp_hit_ago;
+  uint32_t last_nke_hit_ago;
  uint32_t last_cmd_hit_ago;
 } RPY_ClientAccesses_Client;

@@ -629,11 +672,24 @@ typedef struct {
 } RPY_ClientAccessesByIndex;

 typedef struct {
-  uint32_t ntp_hits;
-  uint32_t cmd_hits;
-  uint32_t ntp_drops;
-  uint32_t cmd_drops;
-  uint32_t log_drops;
+  Integer64 ntp_hits;
+  Integer64 nke_hits;
+  Integer64 cmd_hits;
+  Integer64 ntp_drops;
+  Integer64 nke_drops;
+  Integer64 cmd_drops;
+  Integer64 log_drops;
+  Integer64 ntp_auth_hits;
+  Integer64 ntp_interleaved_hits;
+  Integer64 ntp_timestamps;
+  Integer64 ntp_span_seconds;
+  Integer64 ntp_daemon_rx_timestamps;
+  Integer64 ntp_daemon_tx_timestamps;
+  Integer64 ntp_kernel_rx_timestamps;
+  Integer64 ntp_kernel_tx_timestamps;
+  Integer64 ntp_hw_rx_timestamps;
+  Integer64 ntp_hw_tx_timestamps;
+  Integer64 reserved[4];
  int32_t EOR;
 } RPY_ServerStats;

@@ -703,15 +759,55 @@ typedef struct {
  uint32_t total_tx_count;
  uint32_t total_rx_count;
  uint32_t total_valid_count;
-  uint32_t reserved[4];
+  uint32_t total_good_count;
+  uint32_t reserved[3];
  int32_t EOR;
 } RPY_NTPData;

 typedef struct {
-  int8_t name[256];
+  uint8_t name[256];
  int32_t EOR;
 } RPY_NTPSourceName;

+#define RPY_AD_MD_NONE 0
+#define RPY_AD_MD_SYMMETRIC 1
+#define RPY_AD_MD_NTS 2
+
+typedef struct {
+  uint16_t mode;
+  uint16_t key_type;
+  uint32_t key_id;
+  uint16_t key_length;
+  uint16_t ke_attempts;
+  uint32_t last_ke_ago;
+  uint16_t cookies;
+  uint16_t cookie_length;
+  uint16_t nak;
+  uint16_t pad;
+  int32_t EOR;
+} RPY_AuthData;
+
+#define RPY_SD_OPTION_NOSELECT 0x1
+#define RPY_SD_OPTION_PREFER 0x2
+#define RPY_SD_OPTION_TRUST 0x4
+#define RPY_SD_OPTION_REQUIRE 0x8
+
+typedef struct {
+  uint32_t ref_id;
+  IPAddr ip_addr;
+  uint8_t state_char;
+  uint8_t authentication;
+  uint8_t leap;
+  uint8_t pad;
+  uint16_t conf_options;
+  uint16_t eff_options;
+  uint32_t last_sample_ago;
+  Float score;
+  Float lo_limit;
+  Float hi_limit;
+  int32_t EOR;
+} RPY_SelectData;
+
 typedef struct {
  uint8_t version;
  uint8_t pkt_type;
@@ -742,6 +838,8 @@ typedef struct {
    RPY_Smoothing smoothing;
    RPY_NTPData ntp_data;
    RPY_NTPSourceName ntp_source_name;
+    RPY_AuthData auth_data;
+    RPY_SelectData select_data;
  } data; /* Reply specific parameters */

 } CMD_Reply;
--- a/client.c
+++ b/client.c
--- a/clientlog.c
+++ b/clientlog.c
@@ -3,7 +3,7 @@

 **********************************************************************
 * Copyright (C) Richard P. Curnow  1997-2003
- * Copyright (C) Miroslav Lichvar  2009, 2015-2017
+ * Copyright (C) Miroslav Lichvar  2009, 2015-2017, 2021
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
@@ -38,28 +38,24 @@
 #include "array.h"
 #include "clientlog.h"
 #include "conf.h"
+#include "local.h"
 #include "memory.h"
 #include "ntp.h"
 #include "reports.h"
 #include "util.h"
 #include "logging.h"

+#define MAX_SERVICES 3
+
 typedef struct {
  IPAddr ip_addr;
-  uint32_t last_ntp_hit;
-  uint32_t last_cmd_hit;
-  uint32_t ntp_hits;
-  uint32_t cmd_hits;
-  uint16_t ntp_drops;
-  uint16_t cmd_drops;
-  uint16_t ntp_tokens;
-  uint16_t cmd_tokens;
-  int8_t ntp_rate;
-  int8_t cmd_rate;
+  uint32_t last_hit[MAX_SERVICES];
+  uint32_t hits[MAX_SERVICES];
+  uint16_t drops[MAX_SERVICES];
+  uint16_t tokens[MAX_SERVICES];
+  int8_t rate[MAX_SERVICES];
  int8_t ntp_timeout_rate;
-  uint8_t flags;
-  NTP_int64 ntp_rx_ts;
-  NTP_int64 ntp_tx_ts;
+  uint8_t drop_flags;
 } Record;

 /* Hash table of records, there is a fixed number of records per slot */
@@ -104,15 +100,12 @@ static uint32_t ts_offset;
 #define MIN_LIMIT_BURST 1
 #define MAX_LIMIT_BURST 255

-static uint16_t max_ntp_tokens;
-static uint16_t max_cmd_tokens;
-static uint16_t ntp_tokens_per_packet;
-static uint16_t cmd_tokens_per_packet;
+static uint16_t max_tokens[MAX_SERVICES];
+static uint16_t tokens_per_hit[MAX_SERVICES];

 /* Reduction of token rates to avoid overflow of 16-bit counters.  Negative
   shift is used for coarse limiting with intervals shorter than -TS_FRAC. */
-static int ntp_token_shift;
-static int cmd_token_shift;
+static int token_shift[MAX_SERVICES];

 /* Rates at which responses are randomly allowed (in log2) when the
   buckets don't have enough tokens.  This is necessary in order to
@@ -122,30 +115,66 @@ static int cmd_token_shift;
 #define MIN_LEAK_RATE 1
 #define MAX_LEAK_RATE 4

-static int ntp_leak_rate;
-static int cmd_leak_rate;
+static int leak_rate[MAX_SERVICES];

-/* Flag indicating whether the last response was dropped */
-#define FLAG_NTP_DROPPED 0x1
-
-/* NTP limit interval in log2 */
-static int ntp_limit_interval;
+/* Limit intervals in log2 */
+static int limit_interval[MAX_SERVICES];

 /* Flag indicating whether facility is turned on or not */
 static int active;

+/* RX and TX timestamp saved for clients using interleaved mode */
+typedef struct {
+  uint64_t rx_ts;
+  uint8_t flags;
+  uint8_t tx_ts_source;
+  uint16_t slew_epoch;
+  int32_t tx_ts_offset;
+} NtpTimestamps;
+
+/* Flags for NTP timestamps */
+#define NTPTS_DISABLED 1
+#define NTPTS_VALID_TX 2
+
+/* RX->TX map using a circular buffer with ordered timestamps */
+typedef struct {
+  ARR_Instance timestamps;
+  uint32_t first;
+  uint32_t size;
+  uint32_t max_size;
+  uint32_t cached_index;
+  uint64_t cached_rx_ts;
+  uint16_t slew_epoch;
+  double slew_offset;
+} NtpTimestampMap;
+
+static NtpTimestampMap ntp_ts_map;
+
+/* Maximum interval of NTP timestamps in future after a backward step */
+#define NTPTS_FUTURE_LIMIT (1LL << 32) /* 1 second */
+
+/* Maximum number of timestamps moved in the array to insert a new timestamp */
+#define NTPTS_INSERT_LIMIT 64
+
+/* Maximum expected value of the timestamp source */
+#define MAX_NTP_TS NTP_TS_HARDWARE
+
 /* Global statistics */
-static uint32_t total_ntp_hits;
-static uint32_t total_cmd_hits;
-static uint32_t total_ntp_drops;
-static uint32_t total_cmd_drops;
-static uint32_t total_record_drops;
+static uint64_t total_hits[MAX_SERVICES];
+static uint64_t total_drops[MAX_SERVICES];
+static uint64_t total_ntp_auth_hits;
+static uint64_t total_ntp_interleaved_hits;
+static uint64_t total_record_drops;
+static uint64_t total_ntp_rx_timestamps[MAX_NTP_TS + 1];
+static uint64_t total_ntp_tx_timestamps[MAX_NTP_TS + 1];

 #define NSEC_PER_SEC 1000000000U

 /* ================================================== */

 static int expand_hashtable(void);
+static void handle_slew(struct timespec *raw, struct timespec *cooked, double dfreq,
+                        double doffset, LCL_ChangeType change_type, void *anything);

 /* ================================================== */

@@ -161,12 +190,28 @@ compare_ts(uint32_t x, uint32_t y)

 /* ================================================== */

+static int
+compare_total_hits(Record *x, Record *y)
+{
+  uint32_t x_hits, y_hits;
+  int i;
+
+  for (i = 0, x_hits = y_hits = 0; i < MAX_SERVICES; i++) {
+    x_hits += x->hits[i];
+    y_hits += y->hits[i];
+  }
+
+  return x_hits > y_hits ? 1 : -1;
+}
+
+/* ================================================== */
+
 static Record *
 get_record(IPAddr *ip)
 {
-  unsigned int first, i;
-  time_t last_hit, oldest_hit = 0;
+  uint32_t last_hit = 0, oldest_hit = 0;
  Record *record, *oldest_record;
+  unsigned int first, i, j;

  if (!active || (ip->family != IPADDR_INET4 && ip->family != IPADDR_INET6))
    return NULL;
@@ -184,12 +229,13 @@ get_record(IPAddr *ip)
      if (record->ip_addr.family == IPADDR_UNSPEC)
        break;

-      last_hit = compare_ts(record->last_ntp_hit, record->last_cmd_hit) > 0 ?
-                 record->last_ntp_hit : record->last_cmd_hit;
+      for (j = 0; j < MAX_SERVICES; j++) {
+        if (j == 0 || compare_ts(last_hit, record->last_hit[j]) < 0)
+          last_hit = record->last_hit[j];
+      }

      if (!oldest_record || compare_ts(oldest_hit, last_hit) > 0 ||
-          (oldest_hit == last_hit && record->ntp_hits + record->cmd_hits <
-           oldest_record->ntp_hits + oldest_record->cmd_hits)) {
+          (oldest_hit == last_hit && compare_total_hits(oldest_record, record) > 0)) {
        oldest_record = record;
        oldest_hit = last_hit;
      }
@@ -211,16 +257,18 @@ get_record(IPAddr *ip)
  }

  record->ip_addr = *ip;
-  record->last_ntp_hit = record->last_cmd_hit = INVALID_TS;
-  record->ntp_hits = record->cmd_hits = 0;
-  record->ntp_drops = record->cmd_drops = 0;
-  record->ntp_tokens = max_ntp_tokens;
-  record->cmd_tokens = max_cmd_tokens;
-  record->ntp_rate = record->cmd_rate = INVALID_RATE;
+  for (i = 0; i < MAX_SERVICES; i++)
+    record->last_hit[i] = INVALID_TS;
+  for (i = 0; i < MAX_SERVICES; i++)
+    record->hits[i] = 0;
+  for (i = 0; i < MAX_SERVICES; i++)
+    record->drops[i] = 0;
+  for (i = 0; i < MAX_SERVICES; i++)
+    record->tokens[i] = max_tokens[i];
+  for (i = 0; i < MAX_SERVICES; i++)
+    record->rate[i] = INVALID_RATE;
  record->ntp_timeout_rate = INVALID_RATE;
-  record->flags = 0;
-  UTI_ZeroNtp64(&record->ntp_rx_ts);
-  UTI_ZeroNtp64(&record->ntp_tx_ts);
+  record->drop_flags = 0;

  return record;
 }
@@ -306,39 +354,56 @@ set_bucket_params(int interval, int burst, uint16_t *max_tokens,
 void
 CLG_Initialise(void)
 {
-  int interval, burst, leak_rate;
+  int i, interval, burst, lrate, slots2;

-  max_ntp_tokens = max_cmd_tokens = 0;
-  ntp_tokens_per_packet = cmd_tokens_per_packet = 0;
-  ntp_token_shift = cmd_token_shift = 0;
-  ntp_leak_rate = cmd_leak_rate = 0;
-  ntp_limit_interval = MIN_LIMIT_INTERVAL;
+  for (i = 0; i < MAX_SERVICES; i++) {
+    max_tokens[i] = 0;
+    tokens_per_hit[i] = 0;
+    token_shift[i] = 0;
+    leak_rate[i] = 0;
+    limit_interval[i] = MIN_LIMIT_INTERVAL;

-  if (CNF_GetNTPRateLimit(&interval, &burst, &leak_rate)) {
-    set_bucket_params(interval, burst, &max_ntp_tokens, &ntp_tokens_per_packet,
-                      &ntp_token_shift);
-    ntp_leak_rate = CLAMP(MIN_LEAK_RATE, leak_rate, MAX_LEAK_RATE);
-    ntp_limit_interval = CLAMP(MIN_LIMIT_INTERVAL, interval, MAX_LIMIT_INTERVAL);
-  }
+    switch (i) {
+      case CLG_NTP:
+        if (!CNF_GetNTPRateLimit(&interval, &burst, &lrate))
+          continue;
+        break;
+      case CLG_NTSKE:
+        if (!CNF_GetNtsRateLimit(&interval, &burst, &lrate))
+          continue;
+        break;
+      case CLG_CMDMON:
+        if (!CNF_GetCommandRateLimit(&interval, &burst, &lrate))
+          continue;
+        break;
+      default:
+        assert(0);
+    }

-  if (CNF_GetCommandRateLimit(&interval, &burst, &leak_rate)) {
-    set_bucket_params(interval, burst, &max_cmd_tokens, &cmd_tokens_per_packet,
-                      &cmd_token_shift);
-    cmd_leak_rate = CLAMP(MIN_LEAK_RATE, leak_rate, MAX_LEAK_RATE);
+    set_bucket_params(interval, burst, &max_tokens[i], &tokens_per_hit[i], &token_shift[i]);
+    leak_rate[i] = CLAMP(MIN_LEAK_RATE, lrate, MAX_LEAK_RATE);
+    limit_interval[i] = CLAMP(MIN_LIMIT_INTERVAL, interval, MAX_LIMIT_INTERVAL);
  }

  active = !CNF_GetNoClientLog();
  if (!active) {
-    if (ntp_leak_rate || cmd_leak_rate)
-      LOG_FATAL("ratelimit cannot be used with noclientlog");
+    for (i = 0; i < MAX_SERVICES; i++) {
+      if (leak_rate[i] != 0)
+        LOG_FATAL("Rate limiting cannot be enabled with noclientlog");
+    }
    return;
  }

  /* Calculate the maximum number of slots that can be allocated in the
     configured memory limit.  Take into account expanding of the hash
     table where two copies exist at the same time. */
-  max_slots = CNF_GetClientLogLimit() / (sizeof (Record) * SLOT_SIZE * 3 / 2);
+  max_slots = CNF_GetClientLogLimit() /
+              ((sizeof (Record) + sizeof (NtpTimestamps)) * SLOT_SIZE * 3 / 2);
  max_slots = CLAMP(MIN_SLOTS, max_slots, MAX_SLOTS);
+  for (slots2 = 0; 1U << (slots2 + 1) <= max_slots; slots2++)
+    ;
+
+  DEBUG_LOG("Max records %u", 1U << (slots2 + SLOT_BITS));

  slots = 0;
  records = NULL;
@@ -347,6 +412,17 @@ CLG_Initialise(void)

  UTI_GetRandomBytes(&ts_offset, sizeof (ts_offset));
  ts_offset %= NSEC_PER_SEC / (1U << TS_FRAC);
+
+  ntp_ts_map.timestamps = NULL;
+  ntp_ts_map.first = 0;
+  ntp_ts_map.size = 0;
+  ntp_ts_map.max_size = 1U << (slots2 + SLOT_BITS);
+  ntp_ts_map.cached_index = 0;
+  ntp_ts_map.cached_rx_ts = 0ULL;
+  ntp_ts_map.slew_epoch = 0;
+  ntp_ts_map.slew_offset = 0.0;
+
+  LCL_AddParameterChangeHandler(handle_slew, NULL);
 }

 /* ================================================== */
@@ -358,6 +434,10 @@ CLG_Finalise(void)
    return;

  ARR_DestroyInstance(records);
+  if (ntp_ts_map.timestamps)
+    ARR_DestroyInstance(ntp_ts_map.timestamps);
+
+  LCL_RemoveParameterChangeHandler(handle_slew, NULL);
 }

 /* ================================================== */
@@ -380,30 +460,33 @@ get_ts_from_timespec(struct timespec *ts)
 /* ================================================== */

 static void
-update_record(struct timespec *now, uint32_t *last_hit, uint32_t *hits,
-              uint16_t *tokens, uint32_t max_tokens, int token_shift, int8_t *rate)
+update_record(CLG_Service service, Record *record, struct timespec *now)
 {
-  uint32_t interval, now_ts, prev_hit, new_tokens;
-  int interval2;
+  uint32_t interval, now_ts, prev_hit, tokens;
+  int interval2, tshift, mtokens;
+  int8_t *rate;

  now_ts = get_ts_from_timespec(now);

-  prev_hit = *last_hit;
-  *last_hit = now_ts;
-  (*hits)++;
+  prev_hit = record->last_hit[service];
+  record->last_hit[service] = now_ts;
+  record->hits[service]++;

  interval = now_ts - prev_hit;

  if (prev_hit == INVALID_TS || (int32_t)interval < 0)
    return;

-  if (token_shift >= 0)
-    new_tokens = (now_ts >> token_shift) - (prev_hit >> token_shift);
-  else if (now_ts - prev_hit > max_tokens)
-    new_tokens = max_tokens;
+  tshift = token_shift[service];
+  mtokens = max_tokens[service];
+
+  if (tshift >= 0)
+    tokens = (now_ts >> tshift) - (prev_hit >> tshift);
+  else if (now_ts - prev_hit > mtokens)
+    tokens = mtokens;
  else
-    new_tokens = (now_ts - prev_hit) << -token_shift;
-  *tokens = MIN(*tokens + new_tokens, max_tokens);
+    tokens = (now_ts - prev_hit) << -tshift;
+  record->tokens[service] = MIN(record->tokens[service] + tokens, mtokens);

  /* Convert the interval to scaled and rounded log2 */
  if (interval) {
@@ -418,6 +501,11 @@ update_record(struct timespec *now, uint32_t *last_hit, uint32_t *hits,
    interval2 = -RATE_SCALE * (TS_FRAC + 1);
  }

+  /* For the NTP service, update one of the two rates depending on whether
+     the previous request of the client had a reply or it timed out */
+  rate = service == CLG_NTP && record->drop_flags & (1U << service) ?
+           &record->ntp_timeout_rate : &record->rate[service];
+
  /* Update the rate in a rough approximation of exponential moving average */
  if (*rate == INVALID_RATE) {
    *rate = -interval2;
@@ -457,50 +545,33 @@ CLG_GetClientIndex(IPAddr *client)

 /* ================================================== */

-int
-CLG_LogNTPAccess(IPAddr *client, struct timespec *now)
+static void
+check_service_number(CLG_Service service)
 {
-  Record *record;
-
-  total_ntp_hits++;
-
-  record = get_record(client);
-  if (record == NULL)
-    return -1;
-
-  /* Update one of the two rates depending on whether the previous request
-     of the client had a reply or it timed out */
-  update_record(now, &record->last_ntp_hit, &record->ntp_hits,
-                &record->ntp_tokens, max_ntp_tokens, ntp_token_shift,
-                record->flags & FLAG_NTP_DROPPED ?
-                &record->ntp_timeout_rate : &record->ntp_rate);
-
-  DEBUG_LOG("NTP hits %"PRIu32" rate %d trate %d tokens %d",
-            record->ntp_hits, record->ntp_rate, record->ntp_timeout_rate,
-            record->ntp_tokens);
-
-  return get_index(record);
+  assert(service >= 0 && service <= MAX_SERVICES);
 }

 /* ================================================== */

 int
-CLG_LogCommandAccess(IPAddr *client, struct timespec *now)
+CLG_LogServiceAccess(CLG_Service service, IPAddr *client, struct timespec *now)
 {
  Record *record;

-  total_cmd_hits++;
+  check_service_number(service);
+
+  total_hits[service]++;

  record = get_record(client);
  if (record == NULL)
    return -1;

-  update_record(now, &record->last_cmd_hit, &record->cmd_hits,
-                &record->cmd_tokens, max_cmd_tokens, cmd_token_shift,
-                &record->cmd_rate);
+  update_record(service, record, now);

-  DEBUG_LOG("Cmd hits %"PRIu32" rate %d tokens %d",
-            record->cmd_hits, record->cmd_rate, record->cmd_tokens);
+  DEBUG_LOG("service %d hits %"PRIu32" rate %d trate %d tokens %d",
+            (int)service, record->hits[service], record->rate[service],
+            service == CLG_NTP ? record->ntp_timeout_rate : INVALID_RATE,
+            record->tokens[service]);

  return get_index(record);
 }
@@ -530,83 +601,58 @@ limit_response_random(int leak_rate)
 /* ================================================== */

 int
-CLG_LimitNTPResponseRate(int index)
+CLG_LimitServiceRate(CLG_Service service, int index)
 {
  Record *record;
  int drop;

-  if (!ntp_tokens_per_packet)
+  check_service_number(service);
+
+  if (tokens_per_hit[service] == 0)
    return 0;

  record = ARR_GetElement(records, index);
-  record->flags &= ~FLAG_NTP_DROPPED;
+  record->drop_flags &= ~(1U << service);

-  if (record->ntp_tokens >= ntp_tokens_per_packet) {
-    record->ntp_tokens -= ntp_tokens_per_packet;
+  if (record->tokens[service] >= tokens_per_hit[service]) {
+    record->tokens[service] -= tokens_per_hit[service];
    return 0;
  }

-  drop = limit_response_random(ntp_leak_rate);
+  drop = limit_response_random(leak_rate[service]);

-  /* Poorly implemented clients may send new requests at even a higher rate
+  /* Poorly implemented NTP clients can send requests at a higher rate
     when they are not getting replies.  If the request rate seems to be more
     than twice as much as when replies are sent, give up on rate limiting to
     reduce the amount of traffic.  Invert the sense of the leak to respond to
     most of the requests, but still keep the estimated rate updated. */
-  if (record->ntp_timeout_rate != INVALID_RATE &&
-      record->ntp_timeout_rate > record->ntp_rate + RATE_SCALE)
+  if (service == CLG_NTP && record->ntp_timeout_rate != INVALID_RATE &&
+      record->ntp_timeout_rate > record->rate[service] + RATE_SCALE)
    drop = !drop;

  if (!drop) {
-    record->ntp_tokens = 0;
+    record->tokens[service] = 0;
    return 0;
  }

-  record->flags |= FLAG_NTP_DROPPED;
-  record->ntp_drops++;
-  total_ntp_drops++;
+  record->drop_flags |= 1U << service;
+  record->drops[service]++;
+  total_drops[service]++;

  return 1;
 }

 /* ================================================== */

-int
-CLG_LimitCommandResponseRate(int index)
+void
+CLG_UpdateNtpStats(int auth, NTP_Timestamp_Source rx_ts_src, NTP_Timestamp_Source tx_ts_src)
 {
-  Record *record;
-
-  if (!cmd_tokens_per_packet)
-    return 0;
-
-  record = ARR_GetElement(records, index);
-
-  if (record->cmd_tokens >= cmd_tokens_per_packet) {
-    record->cmd_tokens -= cmd_tokens_per_packet;
-    return 0;
-  }
-
-  if (!limit_response_random(cmd_leak_rate)) {
-    record->cmd_tokens = 0;
-    return 0;
-  }
-
-  record->cmd_drops++;
-  total_cmd_drops++;
-
-  return 1;
-}
-
-/* ================================================== */
-
-void CLG_GetNtpTimestamps(int index, NTP_int64 **rx_ts, NTP_int64 **tx_ts)
-{
-  Record *record;
-
-  record = ARR_GetElement(records, index);
-
-  *rx_ts = &record->ntp_rx_ts;
-  *tx_ts = &record->ntp_tx_ts;
+  if (auth)
+    total_ntp_auth_hits++;
+  if (rx_ts_src >= 0 && rx_ts_src <= MAX_NTP_TS)
+    total_ntp_rx_timestamps[rx_ts_src]++;
+  if (tx_ts_src >= 0 && tx_ts_src <= MAX_NTP_TS)
+    total_ntp_tx_timestamps[tx_ts_src]++;
 }

 /* ================================================== */
@@ -614,7 +660,337 @@ void CLG_GetNtpTimestamps(int index, NTP_int64 **rx_ts, NTP_int64 **tx_ts)
 int
 CLG_GetNtpMinPoll(void)
 {
-  return ntp_limit_interval;
+  return limit_interval[CLG_NTP];
+}
+
+/* ================================================== */
+
+static NtpTimestamps *
+get_ntp_tss(uint32_t index)
+{
+  return ARR_GetElement(ntp_ts_map.timestamps,
+                        (ntp_ts_map.first + index) & (ntp_ts_map.max_size - 1));
+}
+
+/* ================================================== */
+
+static int
+find_ntp_rx_ts(uint64_t rx_ts, uint32_t *index)
+{
+  uint64_t rx_x, rx_lo, rx_hi, step;
+  uint32_t i, x, lo, hi;
+
+  if (ntp_ts_map.cached_rx_ts == rx_ts && rx_ts != 0ULL) {
+    *index = ntp_ts_map.cached_index;
+    return 1;
+  }
+
+  if (ntp_ts_map.size == 0) {
+    *index = 0;
+    return 0;
+  }
+
+  lo = 0;
+  hi = ntp_ts_map.size - 1;
+  rx_lo = get_ntp_tss(lo)->rx_ts;
+  rx_hi = get_ntp_tss(hi)->rx_ts;
+
+  /* Check for ts < lo before ts > hi to trim timestamps from "future" later
+     if both conditions are true to not break the order of the endpoints.
+     Compare timestamps by their difference to allow adjacent NTP eras. */
+  if ((int64_t)(rx_ts - rx_lo) < 0) {
+    *index = 0;
+    return 0;
+  } else if ((int64_t)(rx_ts - rx_hi) > 0) {
+    *index = ntp_ts_map.size;
+    return 0;
+  }
+
+  /* Perform a combined linear interpolation and binary search */
+
+  for (i = 0; ; i++) {
+    if (rx_ts == rx_hi) {
+      *index = ntp_ts_map.cached_index = hi;
+      ntp_ts_map.cached_rx_ts = rx_ts;
+      return 1;
+    } else if (rx_ts == rx_lo) {
+      *index = ntp_ts_map.cached_index = lo;
+      ntp_ts_map.cached_rx_ts = rx_ts;
+      return 1;
+    } else if (lo + 1 == hi) {
+      *index = hi;
+      return 0;
+    }
+
+    if (hi - lo > 3 && i % 2 == 0) {
+      step = (rx_hi - rx_lo) / (hi - lo);
+      if (step == 0)
+        step = 1;
+      x = lo + (rx_ts - rx_lo) / step;
+    } else {
+      x = lo + (hi - lo) / 2;
+    }
+
+    if (x <= lo)
+      x = lo + 1;
+    else if (x >= hi)
+      x = hi - 1;
+
+    rx_x = get_ntp_tss(x)->rx_ts;
+
+    if ((int64_t)(rx_x - rx_ts) <= 0) {
+      lo = x;
+      rx_lo = rx_x;
+    } else {
+      hi = x;
+      rx_hi = rx_x;
+    }
+  }
+}
+
+/* ================================================== */
+
+static uint64_t
+ntp64_to_int64(NTP_int64 *ts)
+{
+  return (uint64_t)ntohl(ts->hi) << 32 | ntohl(ts->lo);
+}
+
+/* ================================================== */
+
+static void
+int64_to_ntp64(uint64_t ts, NTP_int64 *ntp_ts)
+{
+  ntp_ts->hi = htonl(ts >> 32);
+  ntp_ts->lo = htonl(ts);
+}
+
+/* ================================================== */
+
+static uint32_t
+push_ntp_tss(uint32_t index)
+{
+  if (ntp_ts_map.size < ntp_ts_map.max_size) {
+    ntp_ts_map.size++;
+  } else {
+    ntp_ts_map.first = (ntp_ts_map.first + 1) % (ntp_ts_map.max_size);
+    if (index > 0)
+      index--;
+  }
+
+  return index;
+}
+
+/* ================================================== */
+
+static void
+set_ntp_tx(NtpTimestamps *tss, NTP_int64 *rx_ts, struct timespec *tx_ts,
+           NTP_Timestamp_Source tx_src)
+{
+  struct timespec ts;
+
+  if (!tx_ts) {
+    tss->flags &= ~NTPTS_VALID_TX;
+    return;
+  }
+
+  UTI_Ntp64ToTimespec(rx_ts, &ts);
+  UTI_DiffTimespecs(&ts, tx_ts, &ts);
+
+  if (ts.tv_sec < -2 || ts.tv_sec > 1) {
+    tss->flags &= ~NTPTS_VALID_TX;
+    return;
+  }
+
+  tss->tx_ts_offset = (int32_t)ts.tv_nsec + (int32_t)ts.tv_sec * (int32_t)NSEC_PER_SEC;
+  tss->flags |= NTPTS_VALID_TX;
+  tss->tx_ts_source = tx_src;
+}
+
+/* ================================================== */
+
+static void
+get_ntp_tx(NtpTimestamps *tss, struct timespec *tx_ts, NTP_Timestamp_Source *tx_src)
+{
+  int32_t offset = tss->tx_ts_offset;
+  NTP_int64 ntp_ts;
+
+  if (tss->flags & NTPTS_VALID_TX) {
+    int64_to_ntp64(tss->rx_ts, &ntp_ts);
+    UTI_Ntp64ToTimespec(&ntp_ts, tx_ts);
+    if (offset >= (int32_t)NSEC_PER_SEC) {
+      offset -= NSEC_PER_SEC;
+      tx_ts->tv_sec++;
+    }
+    tx_ts->tv_nsec += offset;
+    UTI_NormaliseTimespec(tx_ts);
+  } else {
+    UTI_ZeroTimespec(tx_ts);
+  }
+
+  *tx_src = tss->tx_ts_source;
+}
+
+/* ================================================== */
+
+void
+CLG_SaveNtpTimestamps(NTP_int64 *rx_ts, struct timespec *tx_ts, NTP_Timestamp_Source tx_src)
+{
+  NtpTimestamps *tss;
+  uint32_t i, index;
+  uint64_t rx;
+
+  if (!active)
+    return;
+
+  /* Allocate the array on first use */
+  if (!ntp_ts_map.timestamps) {
+    ntp_ts_map.timestamps = ARR_CreateInstance(sizeof (NtpTimestamps));
+    ARR_SetSize(ntp_ts_map.timestamps, ntp_ts_map.max_size);
+  }
+
+  rx = ntp64_to_int64(rx_ts);
+
+  if (rx == 0ULL)
+    return;
+
+  /* Disable the RX timestamp if it already exists to avoid responding
+     with a wrong TX timestamp */
+  if (find_ntp_rx_ts(rx, &index)) {
+    get_ntp_tss(index)->flags |= NTPTS_DISABLED;
+    return;
+  }
+
+  assert(index <= ntp_ts_map.size);
+
+  if (index == ntp_ts_map.size) {
+    /* Increase the size or drop the oldest timestamp to make room for
+       the new timestamp */
+    index = push_ntp_tss(index);
+  } else {
+    /* Trim timestamps in distant future after backward step */
+    while (index < ntp_ts_map.size &&
+           get_ntp_tss(ntp_ts_map.size - 1)->rx_ts - rx > NTPTS_FUTURE_LIMIT)
+      ntp_ts_map.size--;
+
+    /* Insert the timestamp if it is close to the latest timestamp.
+       Otherwise, replace the closest older or the oldest timestamp. */
+    if (index + NTPTS_INSERT_LIMIT >= ntp_ts_map.size) {
+      index = push_ntp_tss(index);
+      for (i = ntp_ts_map.size - 1; i > index; i--)
+        *get_ntp_tss(i) = *get_ntp_tss(i - 1);
+    } else {
+      if (index > 0)
+        index--;
+    }
+  }
+
+  ntp_ts_map.cached_index = index;
+  ntp_ts_map.cached_rx_ts = rx;
+
+  tss = get_ntp_tss(index);
+  tss->rx_ts = rx;
+  tss->flags = 0;
+  tss->slew_epoch = ntp_ts_map.slew_epoch;
+  set_ntp_tx(tss, rx_ts, tx_ts, tx_src);
+
+  DEBUG_LOG("Saved RX+TX index=%"PRIu32" first=%"PRIu32" size=%"PRIu32,
+            index, ntp_ts_map.first, ntp_ts_map.size);
+}
+
+/* ================================================== */
+
+static void
+handle_slew(struct timespec *raw, struct timespec *cooked, double dfreq,
+            double doffset, LCL_ChangeType change_type, void *anything)
+{
+  /* Drop all timestamps on unknown step */
+  if (change_type == LCL_ChangeUnknownStep) {
+    ntp_ts_map.size = 0;
+    ntp_ts_map.cached_rx_ts = 0ULL;
+  }
+
+  ntp_ts_map.slew_epoch++;
+  ntp_ts_map.slew_offset = doffset;
+}
+
+/* ================================================== */
+
+void
+CLG_UndoNtpTxTimestampSlew(NTP_int64 *rx_ts, struct timespec *tx_ts)
+{
+  uint32_t index;
+
+  if (!ntp_ts_map.timestamps)
+    return;
+
+  if (!find_ntp_rx_ts(ntp64_to_int64(rx_ts), &index))
+    return;
+
+  /* If the RX timestamp was captured before the last correction of the clock,
+     remove the adjustment from the TX timestamp */
+  if ((uint16_t)(get_ntp_tss(index)->slew_epoch + 1U) == ntp_ts_map.slew_epoch)
+    UTI_AddDoubleToTimespec(tx_ts, ntp_ts_map.slew_offset, tx_ts);
+}
+
+/* ================================================== */
+
+void
+CLG_UpdateNtpTxTimestamp(NTP_int64 *rx_ts, struct timespec *tx_ts,
+                         NTP_Timestamp_Source tx_src)
+{
+  uint32_t index;
+
+  if (!ntp_ts_map.timestamps)
+    return;
+
+  if (!find_ntp_rx_ts(ntp64_to_int64(rx_ts), &index))
+    return;
+
+  set_ntp_tx(get_ntp_tss(index), rx_ts, tx_ts, tx_src);
+}
+
+/* ================================================== */
+
+int
+CLG_GetNtpTxTimestamp(NTP_int64 *rx_ts, struct timespec *tx_ts,
+                      NTP_Timestamp_Source *tx_src)
+{
+  NtpTimestamps *tss;
+  uint32_t index;
+
+  if (!ntp_ts_map.timestamps)
+    return 0;
+
+  if (!find_ntp_rx_ts(ntp64_to_int64(rx_ts), &index))
+    return 0;
+
+  tss = get_ntp_tss(index);
+
+  if (tss->flags & NTPTS_DISABLED)
+    return 0;
+
+  get_ntp_tx(tss, tx_ts, tx_src);
+
+  return 1;
+}
+
+/* ================================================== */
+
+void
+CLG_DisableNtpTimestamps(NTP_int64 *rx_ts)
+{
+  uint32_t index;
+
+  if (!ntp_ts_map.timestamps)
+    return;
+
+  if (find_ntp_rx_ts(ntp64_to_int64(rx_ts), &index))
+    get_ntp_tss(index)->flags |= NTPTS_DISABLED;
+
+  /* This assumes the function is called only to prevent multiple
+     interleaved responses to the same timestamp */
+  total_ntp_interleaved_hits++;
 }

 /* ================================================== */
@@ -653,10 +1029,12 @@ static uint32_t get_last_ago(uint32_t x, uint32_t y)
 /* ================================================== */

 int
-CLG_GetClientAccessReportByIndex(int index, RPT_ClientAccessByIndex_Report *report, struct timespec *now)
+CLG_GetClientAccessReportByIndex(int index, int reset, uint32_t min_hits,
+                                 RPT_ClientAccessByIndex_Report *report, struct timespec *now)
 {
  Record *record;
  uint32_t now_ts;
+  int i, r;

  if (!active || index < 0 || index >= ARR_GetSize(records))
    return 0;
@@ -666,20 +1044,44 @@ CLG_GetClientAccessReportByIndex(int index, RPT_ClientAccessByIndex_Report *repo
  if (record->ip_addr.family == IPADDR_UNSPEC)
    return 0;

-  now_ts = get_ts_from_timespec(now);
+  if (min_hits == 0) {
+    r = 1;
+  } else {
+    for (i = r = 0; i < MAX_SERVICES; i++) {
+      if (record->hits[i] >= min_hits) {
+        r = 1;
+        break;
+      }
+    }
+  }

-  report->ip_addr = record->ip_addr;
-  report->ntp_hits = record->ntp_hits;
-  report->cmd_hits = record->cmd_hits;
-  report->ntp_drops = record->ntp_drops;
-  report->cmd_drops = record->cmd_drops;
-  report->ntp_interval = get_interval(record->ntp_rate);
-  report->cmd_interval = get_interval(record->cmd_rate);
-  report->ntp_timeout_interval = get_interval(record->ntp_timeout_rate);
-  report->last_ntp_hit_ago = get_last_ago(now_ts, record->last_ntp_hit);
-  report->last_cmd_hit_ago = get_last_ago(now_ts, record->last_cmd_hit);
+  if (r) {
+    now_ts = get_ts_from_timespec(now);

-  return 1;
+    report->ip_addr = record->ip_addr;
+    report->ntp_hits = record->hits[CLG_NTP];
+    report->nke_hits = record->hits[CLG_NTSKE];
+    report->cmd_hits = record->hits[CLG_CMDMON];
+    report->ntp_drops = record->drops[CLG_NTP];
+    report->nke_drops = record->drops[CLG_NTSKE];
+    report->cmd_drops = record->drops[CLG_CMDMON];
+    report->ntp_interval = get_interval(record->rate[CLG_NTP]);
+    report->nke_interval = get_interval(record->rate[CLG_NTSKE]);
+    report->cmd_interval = get_interval(record->rate[CLG_CMDMON]);
+    report->ntp_timeout_interval = get_interval(record->ntp_timeout_rate);
+    report->last_ntp_hit_ago = get_last_ago(now_ts, record->last_hit[CLG_NTP]);
+    report->last_nke_hit_ago = get_last_ago(now_ts, record->last_hit[CLG_NTSKE]);
+    report->last_cmd_hit_ago = get_last_ago(now_ts, record->last_hit[CLG_CMDMON]);
+  }
+
+  if (reset) {
+    for (i = 0; i < MAX_SERVICES; i++) {
+      record->hits[i] = 0;
+      record->drops[i] = 0;
+    }
+  }
+
+  return r;
 }

 /* ================================================== */
@@ -687,9 +1089,23 @@ CLG_GetClientAccessReportByIndex(int index, RPT_ClientAccessByIndex_Report *repo
 void
 CLG_GetServerStatsReport(RPT_ServerStatsReport *report)
 {
-  report->ntp_hits = total_ntp_hits;
-  report->cmd_hits = total_cmd_hits;
-  report->ntp_drops = total_ntp_drops;
-  report->cmd_drops = total_cmd_drops;
+  report->ntp_hits = total_hits[CLG_NTP];
+  report->nke_hits = total_hits[CLG_NTSKE];
+  report->cmd_hits = total_hits[CLG_CMDMON];
+  report->ntp_drops = total_drops[CLG_NTP];
+  report->nke_drops = total_drops[CLG_NTSKE];
+  report->cmd_drops = total_drops[CLG_CMDMON];
  report->log_drops = total_record_drops;
+  report->ntp_auth_hits = total_ntp_auth_hits;
+  report->ntp_interleaved_hits = total_ntp_interleaved_hits;
+  report->ntp_timestamps = ntp_ts_map.size;
+  report->ntp_span_seconds = ntp_ts_map.size > 1 ?
+                             (get_ntp_tss(ntp_ts_map.size - 1)->rx_ts -
+                              get_ntp_tss(0)->rx_ts) >> 32 : 0;
+  report->ntp_daemon_rx_timestamps = total_ntp_rx_timestamps[NTP_TS_DAEMON];
+  report->ntp_daemon_tx_timestamps = total_ntp_tx_timestamps[NTP_TS_DAEMON];
+  report->ntp_kernel_rx_timestamps = total_ntp_rx_timestamps[NTP_TS_KERNEL];
+  report->ntp_kernel_tx_timestamps = total_ntp_tx_timestamps[NTP_TS_KERNEL];
+  report->ntp_hw_rx_timestamps = total_ntp_rx_timestamps[NTP_TS_HARDWARE];
+  report->ntp_hw_tx_timestamps = total_ntp_tx_timestamps[NTP_TS_HARDWARE];
 }
--- a/clientlog.h
+++ b/clientlog.h
@@ -31,20 +31,37 @@
 #include "sysincl.h"
 #include "reports.h"

+typedef enum {
+  CLG_NTP = 0,
+  CLG_NTSKE,
+  CLG_CMDMON,
+} CLG_Service;
+
 extern void CLG_Initialise(void);
 extern void CLG_Finalise(void);
 extern int CLG_GetClientIndex(IPAddr *client);
-extern int CLG_LogNTPAccess(IPAddr *client, struct timespec *now);
-extern int CLG_LogCommandAccess(IPAddr *client, struct timespec *now);
-extern int CLG_LimitNTPResponseRate(int index);
-extern int CLG_LimitCommandResponseRate(int index);
-extern void CLG_GetNtpTimestamps(int index, NTP_int64 **rx_ts, NTP_int64 **tx_ts);
+extern int CLG_LogServiceAccess(CLG_Service service, IPAddr *client, struct timespec *now);
+extern int CLG_LimitServiceRate(CLG_Service service, int index);
+extern void CLG_UpdateNtpStats(int auth, NTP_Timestamp_Source rx_ts_src,
+                               NTP_Timestamp_Source tx_ts_src);
 extern int CLG_GetNtpMinPoll(void);

+/* Functions to save and retrieve timestamps for server interleaved mode */
+extern void CLG_SaveNtpTimestamps(NTP_int64 *rx_ts, struct timespec *tx_ts,
+                                  NTP_Timestamp_Source tx_src);
+extern void CLG_UndoNtpTxTimestampSlew(NTP_int64 *rx_ts, struct timespec *tx_ts);
+extern void CLG_UpdateNtpTxTimestamp(NTP_int64 *rx_ts, struct timespec *tx_ts,
+                                     NTP_Timestamp_Source tx_src);
+extern int CLG_GetNtpTxTimestamp(NTP_int64 *rx_ts, struct timespec *tx_ts,
+                                 NTP_Timestamp_Source *tx_src);
+extern void CLG_DisableNtpTimestamps(NTP_int64 *rx_ts);
+
 /* And some reporting functions, for use by chronyc. */

 extern int CLG_GetNumberOfIndices(void);
-extern int CLG_GetClientAccessReportByIndex(int index, RPT_ClientAccessByIndex_Report *report, struct timespec *now);
+extern int CLG_GetClientAccessReportByIndex(int index, int reset, uint32_t min_hits,
+                                            RPT_ClientAccessByIndex_Report *report,
+                                            struct timespec *now);
 extern void CLG_GetServerStatsReport(RPT_ServerStatsReport *report);

 #endif /* GOT_CLIENTLOG_H */
--- a/cmac.h
+++ b/cmac.h
@@ -28,13 +28,20 @@
 #ifndef GOT_CMAC_H
 #define GOT_CMAC_H

+/* Avoid overlapping with the hash enumeration */
+typedef enum {
+  CMC_INVALID = 0,
+  CMC_AES128 = 13,
+  CMC_AES256 = 14,
+} CMC_Algorithm;
+
 typedef struct CMC_Instance_Record *CMC_Instance;

-extern unsigned int CMC_GetKeyLength(const char *cipher);
-extern CMC_Instance CMC_CreateInstance(const char *cipher, const unsigned char *key,
-                                       unsigned int length);
-extern unsigned int CMC_Hash(CMC_Instance inst, const unsigned char *in, unsigned int in_len,
-                             unsigned char *out, unsigned int out_len);
+extern int CMC_GetKeyLength(CMC_Algorithm algorithm);
+extern CMC_Instance CMC_CreateInstance(CMC_Algorithm algorithm, const unsigned char *key,
+                                       int length);
+extern int CMC_Hash(CMC_Instance inst, const void *in, int in_len,
+                    unsigned char *out, int out_len);
 extern void CMC_DestroyInstance(CMC_Instance inst);

 #endif
--- a/cmac_gnutls.c
+++ b/cmac_gnutls.c
@@ -0,0 +1,189 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2021
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  CMAC using the GnuTLS library
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <gnutls/crypto.h>
+
+#include "cmac.h"
+#include "hash.h"
+#include "logging.h"
+#include "memory.h"
+
+struct CMC_Instance_Record {
+  gnutls_mac_algorithm_t algorithm;
+  gnutls_hmac_hd_t mac;
+};
+
+/* ================================================== */
+
+static int instance_counter = 0;
+static int gnutls_initialised = 0;
+
+/* ================================================== */
+
+static void
+init_gnutls(void)
+{
+  int r;
+
+  if (gnutls_initialised)
+    return;
+
+  r = gnutls_global_init();
+  if (r < 0)
+    LOG_FATAL("Could not initialise %s : %s", "gnutls", gnutls_strerror(r));
+
+  DEBUG_LOG("Initialised");
+  gnutls_initialised = 1;
+}
+
+/* ================================================== */
+
+static void
+deinit_gnutls(void)
+{
+  assert(gnutls_initialised);
+  gnutls_global_deinit();
+  gnutls_initialised = 0;
+  DEBUG_LOG("Deinitialised");
+}
+
+/* ================================================== */
+
+static gnutls_mac_algorithm_t
+get_mac_algorithm(CMC_Algorithm algorithm)
+{
+  switch (algorithm) {
+    case CMC_AES128:
+      return GNUTLS_MAC_AES_CMAC_128;
+    case CMC_AES256:
+      return GNUTLS_MAC_AES_CMAC_256;
+    default:
+      return GNUTLS_MAC_UNKNOWN;
+  }
+}
+
+/* ================================================== */
+
+int
+CMC_GetKeyLength(CMC_Algorithm algorithm)
+{
+  gnutls_mac_algorithm_t malgo = get_mac_algorithm(algorithm);
+  int len;
+
+  if (malgo == GNUTLS_MAC_UNKNOWN)
+    return 0;
+
+  len = gnutls_hmac_get_key_size(malgo);
+
+  if (len < 0)
+    return 0;
+
+  return len;
+}
+
+/* ================================================== */
+
+CMC_Instance
+CMC_CreateInstance(CMC_Algorithm algorithm, const unsigned char *key, int length)
+{
+  gnutls_hmac_hd_t handle;
+  CMC_Instance inst;
+
+  int r;
+
+  if (instance_counter == 0)
+    init_gnutls();
+
+  if (length <= 0 || length != CMC_GetKeyLength(algorithm))
+    goto error;
+
+  r = gnutls_hmac_init(&handle, get_mac_algorithm(algorithm), key, length);
+  if (r < 0) {
+    DEBUG_LOG("Could not initialise %s : %s", "mac", gnutls_strerror(r));
+    goto error;
+  }
+
+  inst = MallocNew(struct CMC_Instance_Record);
+  inst->algorithm = get_mac_algorithm(algorithm);
+  inst->mac = handle;
+
+  instance_counter++;
+
+  return inst;
+
+error:
+  if (instance_counter == 0)
+    deinit_gnutls();
+  return NULL;
+}
+
+/* ================================================== */
+
+int
+CMC_Hash(CMC_Instance inst, const void *in, int in_len, unsigned char *out, int out_len)
+{
+  unsigned char buf[MAX_HASH_LENGTH];
+  int hash_len;
+
+  if (in_len < 0 || out_len < 0)
+    return 0;
+
+  hash_len = gnutls_hmac_get_len(inst->algorithm);
+
+  if (out_len > hash_len)
+    out_len = hash_len;
+
+  if (hash_len > sizeof (buf))
+    return 0;
+
+  if (gnutls_hmac(inst->mac, in, in_len) < 0) {
+    /* Reset the state */
+    gnutls_hmac_output(inst->mac, buf);
+    return 0;
+  }
+
+  gnutls_hmac_output(inst->mac, buf);
+  memcpy(out, buf, out_len);
+
+  return out_len;
+}
+
+/* ================================================== */
+
+void
+CMC_DestroyInstance(CMC_Instance inst)
+{
+  gnutls_hmac_deinit(inst->mac, NULL);
+  Free(inst);
+
+  instance_counter--;
+  if (instance_counter == 0)
+    deinit_gnutls();
+}
--- a/cmac_nettle.c
+++ b/cmac_nettle.c
@@ -44,12 +44,12 @@ struct CMC_Instance_Record {

 /* ================================================== */

-unsigned int
-CMC_GetKeyLength(const char *cipher)
+int
+CMC_GetKeyLength(CMC_Algorithm algorithm)
 {
-  if (strcmp(cipher, "AES128") == 0)
+  if (algorithm == CMC_AES128)
    return AES128_KEY_SIZE;
-  else if (strcmp(cipher, "AES256") == 0)
+  else if (algorithm == CMC_AES256)
    return AES256_KEY_SIZE;
  return 0;
 }
@@ -57,11 +57,11 @@ CMC_GetKeyLength(const char *cipher)
 /* ================================================== */

 CMC_Instance
-CMC_CreateInstance(const char *cipher, const unsigned char *key, unsigned int length)
+CMC_CreateInstance(CMC_Algorithm algorithm, const unsigned char *key, int length)
 {
  CMC_Instance inst;

-  if (length == 0 || length != CMC_GetKeyLength(cipher))
+  if (length <= 0 || length != CMC_GetKeyLength(algorithm))
    return NULL;

  inst = MallocNew(struct CMC_Instance_Record);
@@ -83,10 +83,12 @@ CMC_CreateInstance(const char *cipher, const unsigned char *key, unsigned int le

 /* ================================================== */

-unsigned int
-CMC_Hash(CMC_Instance inst, const unsigned char *in, unsigned int in_len,
-         unsigned char *out, unsigned int out_len)
+int
+CMC_Hash(CMC_Instance inst, const void *in, int in_len, unsigned char *out, int out_len)
 {
+  if (in_len < 0 || out_len < 0)
+    return 0;
+
  if (out_len > CMAC128_DIGEST_SIZE)
    out_len = CMAC128_DIGEST_SIZE;

--- a/cmdmon.c
+++ b/cmdmon.c
@@ -3,7 +3,7 @@

 **********************************************************************
 * Copyright (C) Richard P. Curnow  1997-2003
- * Copyright (C) Miroslav Lichvar  2009-2016, 2018
+ * Copyright (C) Miroslav Lichvar  2009-2016, 2018-2023
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
@@ -44,6 +44,7 @@
 #include "reference.h"
 #include "manual.h"
 #include "memory.h"
+#include "nts_ke_server.h"
 #include "local.h"
 #include "addrfilt.h"
 #include "conf.h"
@@ -61,6 +62,9 @@ static int sock_fdu;
 static int sock_fd4;
 static int sock_fd6;

+/* Flag indicating the IPv4 socket is bound to an address */
+static int bound_sock_fd4;
+
 /* Flag indicating whether this module has been initialised or not */
 static int initialised = 0;

@@ -134,7 +138,13 @@ static const char permissions[] = {
  PERMIT_AUTH, /* ONOFFLINE */
  PERMIT_AUTH, /* ADD_SOURCE */
  PERMIT_OPEN, /* NTP_SOURCE_NAME */
-  PERMIT_AUTH, /* RESET */
+  PERMIT_AUTH, /* RESET_SOURCES */
+  PERMIT_AUTH, /* AUTH_DATA */
+  PERMIT_AUTH, /* CLIENT_ACCESSES_BY_INDEX3 */
+  PERMIT_AUTH, /* SELECT_DATA */
+  PERMIT_AUTH, /* RELOAD_SOURCES */
+  PERMIT_AUTH, /* DOFFSET2 */
+  PERMIT_AUTH, /* MODIFY_SELECTOPTS */
 };

 /* ================================================== */
@@ -152,29 +162,31 @@ static void read_from_cmd_socket(int sock_fd, int event, void *anything);
 static int
 open_socket(int family)
 {
+  const char *local_path, *iface;
  IPSockAddr local_addr;
-  const char *local_path;
  int sock_fd, port;

  switch (family) {
    case IPADDR_INET4:
    case IPADDR_INET6:
      port = CNF_GetCommandPort();
-      if (port == 0 || !SCK_IsFamilySupported(family))
+      if (port == 0 || !SCK_IsIpFamilyEnabled(family))
        return INVALID_SOCK_FD;

      CNF_GetBindCommandAddress(family, &local_addr.ip_addr);
-      if (local_addr.ip_addr.family != family)
-        SCK_GetLoopbackIPAddress(family, &local_addr.ip_addr);
      local_addr.port = port;
+      iface = CNF_GetBindCommandInterface();

-      sock_fd = SCK_OpenUdpSocket(NULL, &local_addr, SCK_FLAG_RX_DEST_ADDR);
+      sock_fd = SCK_OpenUdpSocket(NULL, &local_addr, iface, SCK_FLAG_RX_DEST_ADDR);
      if (sock_fd < 0) {
        LOG(LOGS_ERR, "Could not open command socket on %s",
            UTI_IPSockAddrToString(&local_addr));
        return INVALID_SOCK_FD;
      }

+      if (family == IPADDR_INET4)
+        bound_sock_fd4 = local_addr.ip_addr.addr.in4 != INADDR_ANY;
+
      break;
    case IPADDR_UNSPEC:
      local_path = CNF_GetBindCommandPath();
@@ -232,22 +244,19 @@ do_size_checks(void)
 /* ================================================== */

 void
-CAM_Initialise(int family)
+CAM_Initialise(void)
 {
  assert(!initialised);
  assert(sizeof (permissions) / sizeof (permissions[0]) == N_REQUEST_TYPES);
  do_size_checks();

  initialised = 1;
+
+  bound_sock_fd4 = 0;
+
  sock_fdu = INVALID_SOCK_FD;
-  sock_fd4 = INVALID_SOCK_FD;
-  sock_fd6 = INVALID_SOCK_FD;
-
-  if (family == IPADDR_UNSPEC || family == IPADDR_INET4)
-    sock_fd4 = open_socket(IPADDR_INET4);
-
-  if (family == IPADDR_UNSPEC || family == IPADDR_INET6)
-    sock_fd6 = open_socket(IPADDR_INET6);
+  sock_fd4 = open_socket(IPADDR_INET4);
+  sock_fd6 = open_socket(IPADDR_INET6);

  access_auth_table = ADF_CreateTable();
 }
@@ -288,17 +297,36 @@ CAM_OpenUnixSocket(void)
 {
  /* This is separated from CAM_Initialise() as it needs to be called when
     the process has already dropped the root privileges */
-  if (CNF_GetBindCommandPath()[0])
+  if (CNF_GetBindCommandPath())
    sock_fdu = open_socket(IPADDR_UNSPEC);
 }

 /* ================================================== */

 static void
-transmit_reply(int sock_fd, SCK_Message *message)
+transmit_reply(int sock_fd, int request_length, SCK_Message *message)
 {
  message->length = PKL_ReplyLength((CMD_Reply *)message->data);

+  if (request_length < message->length) {
+    DEBUG_LOG("Response longer than request req_len=%d res_len=%d",
+              request_length, message->length);
+    return;
+  }
+
+  /* Don't require responses to non-link-local addresses to use the same
+     interface */
+  if (message->addr_type == SCK_ADDR_IP &&
+      !SCK_IsLinkLocalIPAddress(&message->remote_addr.ip.ip_addr))
+    message->if_index = INVALID_IF_INDEX;
+
+#if !defined(HAVE_IN_PKTINFO) && defined(IP_SENDSRCADDR)
+  /* On FreeBSD a local IPv4 address cannot be specified on bound socket */
+  if (message->addr_type == SCK_ADDR_IP && message->local_addr.ip.family == IPADDR_INET4 &&
+      (sock_fd != sock_fd4 || bound_sock_fd4))
+    message->local_addr.ip.family = IPADDR_UNSPEC;
+#endif
+
  if (!SCK_SendMessage(sock_fd, message, 0))
    return;
 }
@@ -309,6 +337,8 @@ static void
 handle_dump(CMD_Request *rx_message, CMD_Reply *tx_message)
 {
  SRC_DumpSources();
+  NSR_DumpAuthData();
+  NKS_DumpKeys();
 }

 /* ================================================== */
@@ -566,11 +596,8 @@ handle_source_data(CMD_Request *rx_message, CMD_Reply *tx_message)
    tx_message->data.source_data.stratum = htons(report.stratum);
    tx_message->data.source_data.poll    = htons(report.poll);
    switch (report.state) {
-      case RPT_SYNC:
-        tx_message->data.source_data.state   = htons(RPY_SD_ST_SYNC);
-        break;
-      case RPT_UNREACH:
-        tx_message->data.source_data.state   = htons(RPY_SD_ST_UNREACH);
+      case RPT_NONSELECTABLE:
+        tx_message->data.source_data.state   = htons(RPY_SD_ST_NONSELECTABLE);
        break;
      case RPT_FALSETICKER:
        tx_message->data.source_data.state   = htons(RPY_SD_ST_FALSETICKER);
@@ -578,11 +605,14 @@ handle_source_data(CMD_Request *rx_message, CMD_Reply *tx_message)
      case RPT_JITTERY:
        tx_message->data.source_data.state   = htons(RPY_SD_ST_JITTERY);
        break;
-      case RPT_CANDIDATE:
-        tx_message->data.source_data.state   = htons(RPY_SD_ST_CANDIDATE);
+      case RPT_SELECTABLE:
+        tx_message->data.source_data.state   = htons(RPY_SD_ST_SELECTABLE);
        break;
-      case RPT_OUTLIER:
-        tx_message->data.source_data.state   = htons(RPY_SD_ST_OUTLIER);
+      case RPT_UNSELECTED:
+        tx_message->data.source_data.state   = htons(RPY_SD_ST_UNSELECTED);
+        break;
+      case RPT_SELECTED:
+        tx_message->data.source_data.state   = htons(RPY_SD_ST_SELECTED);
        break;
    }
    switch (report.mode) {
@@ -596,11 +626,7 @@ handle_source_data(CMD_Request *rx_message, CMD_Reply *tx_message)
        tx_message->data.source_data.mode    = htons(RPY_SD_MD_REF);
        break;
    }
-    tx_message->data.source_data.flags =
-                  htons((report.sel_options & SRC_SELECT_PREFER ? RPY_SD_FLAG_PREFER : 0) |
-                        (report.sel_options & SRC_SELECT_NOSELECT ? RPY_SD_FLAG_NOSELECT : 0) |
-                        (report.sel_options & SRC_SELECT_TRUST ? RPY_SD_FLAG_TRUST : 0) |
-                        (report.sel_options & SRC_SELECT_REQUIRE ? RPY_SD_FLAG_REQUIRE : 0));
+    tx_message->data.source_data.flags = htons(0);
    tx_message->data.source_data.reachability = htons(report.reachability);
    tx_message->data.source_data.since_sample = htonl(report.latest_meas_ago);
    tx_message->data.source_data.orig_latest_meas = UTI_FloatHostToNetwork(report.orig_latest_meas);
@@ -617,6 +643,7 @@ static void
 handle_rekey(CMD_Request *rx_message, CMD_Reply *tx_message)
 {
  KEY_Reload();
+  NKS_ReloadKeys();
 }

 /* ================================================== */
@@ -677,6 +704,17 @@ handle_cmdaccheck(CMD_Request *rx_message, CMD_Reply *tx_message)

 /* ================================================== */

+static int
+convert_addsrc_select_options(int flags)
+{
+    return (flags & REQ_ADDSRC_PREFER ? SRC_SELECT_PREFER : 0) |
+           (flags & REQ_ADDSRC_NOSELECT ? SRC_SELECT_NOSELECT : 0) |
+           (flags & REQ_ADDSRC_TRUST ? SRC_SELECT_TRUST : 0) |
+           (flags & REQ_ADDSRC_REQUIRE ? SRC_SELECT_REQUIRE : 0);
+}
+
+/* ================================================== */
+
 static void
 handle_add_source(CMD_Request *rx_message, CMD_Reply *tx_message)
 {
@@ -712,7 +750,7 @@ handle_add_source(CMD_Request *rx_message, CMD_Reply *tx_message)
      return;
  }

-  port = (unsigned short)(ntohl(rx_message->data.ntp_source.port));
+  port = ntohl(rx_message->data.ntp_source.port);
  params.minpoll = ntohl(rx_message->data.ntp_source.minpoll);
  params.maxpoll = ntohl(rx_message->data.ntp_source.maxpoll);
  params.presend_minpoll = ntohl(rx_message->data.ntp_source.presend_minpoll);
@@ -725,11 +763,14 @@ handle_add_source(CMD_Request *rx_message, CMD_Reply *tx_message)
  params.filter_length = ntohl(rx_message->data.ntp_source.filter_length);
  params.authkey = ntohl(rx_message->data.ntp_source.authkey);
  params.nts_port = ntohl(rx_message->data.ntp_source.nts_port);
+  params.cert_set = ntohl(rx_message->data.ntp_source.cert_set);
  params.max_delay = UTI_FloatNetworkToHost(rx_message->data.ntp_source.max_delay);
  params.max_delay_ratio =
    UTI_FloatNetworkToHost(rx_message->data.ntp_source.max_delay_ratio);
  params.max_delay_dev_ratio =
    UTI_FloatNetworkToHost(rx_message->data.ntp_source.max_delay_dev_ratio);
+  params.max_delay_quant =
+    UTI_FloatNetworkToHost(rx_message->data.ntp_source.max_delay_quant);
  params.min_delay = UTI_FloatNetworkToHost(rx_message->data.ntp_source.min_delay);
  params.asymmetry = UTI_FloatNetworkToHost(rx_message->data.ntp_source.asymmetry);
  params.offset = UTI_FloatNetworkToHost(rx_message->data.ntp_source.offset);
@@ -741,13 +782,12 @@ handle_add_source(CMD_Request *rx_message, CMD_Reply *tx_message)
  params.interleaved = ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_INTERLEAVED ? 1 : 0;
  params.burst = ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_BURST ? 1 : 0;
  params.nts = ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_NTS ? 1 : 0;
-  params.sel_options =
-    (ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_PREFER ? SRC_SELECT_PREFER : 0) |
-    (ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_NOSELECT ? SRC_SELECT_NOSELECT : 0) |
-    (ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_TRUST ? SRC_SELECT_TRUST : 0) |
-    (ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_REQUIRE ? SRC_SELECT_REQUIRE : 0);
+  params.copy = ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_COPY ? 1 : 0;
+  params.ext_fields =
+    ntohl(rx_message->data.ntp_source.flags) & REQ_ADDSRC_EF_EXP1 ? NTP_EF_FLAG_EXP1 : 0;
+  params.sel_options = convert_addsrc_select_options(ntohl(rx_message->data.ntp_source.flags));

-  status = NSR_AddSourceByName(name, port, pool, type, &params);
+  status = NSR_AddSourceByName(name, port, pool, type, &params, NULL);
  switch (status) {
    case NSR_Success:
      break;
@@ -776,13 +816,12 @@ handle_add_source(CMD_Request *rx_message, CMD_Reply *tx_message)
 static void
 handle_del_source(CMD_Request *rx_message, CMD_Reply *tx_message)
 {
-  NTP_Remote_Address rem_addr;
  NSR_Status status;
+  IPAddr ip_addr;
  
-  UTI_IPNetworkToHost(&rx_message->data.del_source.ip_addr, &rem_addr.ip_addr);
-  rem_addr.port = 0;
+  UTI_IPNetworkToHost(&rx_message->data.del_source.ip_addr, &ip_addr);
  
-  status = NSR_RemoveSource(&rem_addr);
+  status = NSR_RemoveSource(&ip_addr);
  switch (status) {
    case NSR_Success:
      break;
@@ -832,13 +871,14 @@ handle_dfreq(CMD_Request *rx_message, CMD_Reply *tx_message)
 static void
 handle_doffset(CMD_Request *rx_message, CMD_Reply *tx_message)
 {
-  long sec, usec;
  double doffset;
-  sec = (int32_t)ntohl(rx_message->data.doffset.sec);
-  usec = (int32_t)ntohl(rx_message->data.doffset.usec);
-  doffset = (double) sec + 1.0e-6 * (double) usec;
-  LOG(LOGS_INFO, "Accumulated delta offset of %.6f seconds", doffset);
-  LCL_AccumulateOffset(doffset, 0.0);
+
+  doffset = UTI_FloatNetworkToHost(rx_message->data.doffset.doffset);
+  if (!LCL_AccumulateOffset(doffset, 0.0)) {
+    tx_message->status = htons(STT_FAILED);
+  } else {
+    LOG(LOGS_INFO, "Accumulated delta offset of %.6f seconds", doffset);
+  }
 }

 /* ================================================== */
@@ -996,7 +1036,7 @@ handle_client_accesses_by_index(CMD_Request *rx_message, CMD_Reply *tx_message)
  RPT_ClientAccessByIndex_Report report;
  RPY_ClientAccesses_Client *client;
  int n_indices;
-  uint32_t i, j, req_first_index, req_n_clients;
+  uint32_t i, j, req_first_index, req_n_clients, req_min_hits, req_reset;
  struct timespec now;

  SCH_GetLastEventTime(&now, NULL, NULL);
@@ -1005,6 +1045,8 @@ handle_client_accesses_by_index(CMD_Request *rx_message, CMD_Reply *tx_message)
  req_n_clients = ntohl(rx_message->data.client_accesses_by_index.n_clients);
  if (req_n_clients > MAX_CLIENT_ACCESSES)
    req_n_clients = MAX_CLIENT_ACCESSES;
+  req_min_hits = ntohl(rx_message->data.client_accesses_by_index.min_hits);
+  req_reset = ntohl(rx_message->data.client_accesses_by_index.reset);

  n_indices = CLG_GetNumberOfIndices();
  if (n_indices < 0) {
@@ -1012,24 +1054,28 @@ handle_client_accesses_by_index(CMD_Request *rx_message, CMD_Reply *tx_message)
    return;
  }

-  tx_message->reply = htons(RPY_CLIENT_ACCESSES_BY_INDEX2);
+  tx_message->reply = htons(RPY_CLIENT_ACCESSES_BY_INDEX3);
  tx_message->data.client_accesses_by_index.n_indices = htonl(n_indices);

  for (i = req_first_index, j = 0; i < (uint32_t)n_indices && j < req_n_clients; i++) {
-    if (!CLG_GetClientAccessReportByIndex(i, &report, &now))
+    if (!CLG_GetClientAccessReportByIndex(i, req_reset, req_min_hits, &report, &now))
      continue;

    client = &tx_message->data.client_accesses_by_index.clients[j++];

    UTI_IPHostToNetwork(&report.ip_addr, &client->ip);
    client->ntp_hits = htonl(report.ntp_hits);
+    client->nke_hits = htonl(report.nke_hits);
    client->cmd_hits = htonl(report.cmd_hits);
    client->ntp_drops = htonl(report.ntp_drops);
+    client->nke_drops = htonl(report.nke_drops);
    client->cmd_drops = htonl(report.cmd_drops);
    client->ntp_interval = report.ntp_interval;
+    client->nke_interval = report.nke_interval;
    client->cmd_interval = report.cmd_interval;
    client->ntp_timeout_interval = report.ntp_timeout_interval;
    client->last_ntp_hit_ago = htonl(report.last_ntp_hit_ago);
+    client->last_nke_hit_ago = htonl(report.last_nke_hit_ago);
    client->last_cmd_hit_ago = htonl(report.last_cmd_hit_ago);
  }

@@ -1131,12 +1177,36 @@ handle_server_stats(CMD_Request *rx_message, CMD_Reply *tx_message)
  RPT_ServerStatsReport report;

  CLG_GetServerStatsReport(&report);
-  tx_message->reply = htons(RPY_SERVER_STATS);
-  tx_message->data.server_stats.ntp_hits = htonl(report.ntp_hits);
-  tx_message->data.server_stats.cmd_hits = htonl(report.cmd_hits);
-  tx_message->data.server_stats.ntp_drops = htonl(report.ntp_drops);
-  tx_message->data.server_stats.cmd_drops = htonl(report.cmd_drops);
-  tx_message->data.server_stats.log_drops = htonl(report.log_drops);
+  tx_message->reply = htons(RPY_SERVER_STATS4);
+  tx_message->data.server_stats.ntp_hits = UTI_Integer64HostToNetwork(report.ntp_hits);
+  tx_message->data.server_stats.nke_hits = UTI_Integer64HostToNetwork(report.nke_hits);
+  tx_message->data.server_stats.cmd_hits = UTI_Integer64HostToNetwork(report.cmd_hits);
+  tx_message->data.server_stats.ntp_drops = UTI_Integer64HostToNetwork(report.ntp_drops);
+  tx_message->data.server_stats.nke_drops = UTI_Integer64HostToNetwork(report.nke_drops);
+  tx_message->data.server_stats.cmd_drops = UTI_Integer64HostToNetwork(report.cmd_drops);
+  tx_message->data.server_stats.log_drops = UTI_Integer64HostToNetwork(report.log_drops);
+  tx_message->data.server_stats.ntp_auth_hits =
+    UTI_Integer64HostToNetwork(report.ntp_auth_hits);
+  tx_message->data.server_stats.ntp_interleaved_hits =
+    UTI_Integer64HostToNetwork(report.ntp_interleaved_hits);
+  tx_message->data.server_stats.ntp_timestamps =
+    UTI_Integer64HostToNetwork(report.ntp_timestamps);
+  tx_message->data.server_stats.ntp_span_seconds =
+    UTI_Integer64HostToNetwork(report.ntp_span_seconds);
+  tx_message->data.server_stats.ntp_daemon_rx_timestamps =
+    UTI_Integer64HostToNetwork(report.ntp_daemon_rx_timestamps);
+  tx_message->data.server_stats.ntp_daemon_tx_timestamps =
+    UTI_Integer64HostToNetwork(report.ntp_daemon_tx_timestamps);
+  tx_message->data.server_stats.ntp_kernel_rx_timestamps =
+    UTI_Integer64HostToNetwork(report.ntp_kernel_rx_timestamps);
+  tx_message->data.server_stats.ntp_kernel_tx_timestamps =
+    UTI_Integer64HostToNetwork(report.ntp_kernel_tx_timestamps);
+  tx_message->data.server_stats.ntp_hw_rx_timestamps =
+    UTI_Integer64HostToNetwork(report.ntp_hw_rx_timestamps);
+  tx_message->data.server_stats.ntp_hw_tx_timestamps =
+    UTI_Integer64HostToNetwork(report.ntp_hw_tx_timestamps);
+  memset(tx_message->data.server_stats.reserved, 0xff,
+         sizeof (tx_message->data.server_stats.reserved));
 }

 /* ================================================== */
@@ -1180,6 +1250,7 @@ handle_ntp_data(CMD_Request *rx_message, CMD_Reply *tx_message)
  tx_message->data.ntp_data.total_tx_count = htonl(report.total_tx_count);
  tx_message->data.ntp_data.total_rx_count = htonl(report.total_rx_count);
  tx_message->data.ntp_data.total_valid_count = htonl(report.total_valid_count);
+  tx_message->data.ntp_data.total_good_count = htonl(report.total_good_count);
  memset(tx_message->data.ntp_data.reserved, 0xff, sizeof (tx_message->data.ntp_data.reserved));
 }

@@ -1200,7 +1271,7 @@ handle_ntp_source_name(CMD_Request *rx_message, CMD_Reply *tx_message)
  IPAddr addr;
  char *name;

-  UTI_IPNetworkToHost(&rx_message->data.ntp_data.ip_addr, &addr);
+  UTI_IPNetworkToHost(&rx_message->data.ntp_source_name.ip_addr, &addr);
  name = NSR_GetName(&addr);

  if (!name) {
@@ -1222,7 +1293,15 @@ handle_ntp_source_name(CMD_Request *rx_message, CMD_Reply *tx_message)
 /* ================================================== */

 static void
-handle_reset(CMD_Request *rx_message, CMD_Reply *tx_message)
+handle_reload_sources(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  CNF_ReloadSources();
+}
+
+/* ================================================== */
+
+static void
+handle_reset_sources(CMD_Request *rx_message, CMD_Reply *tx_message)
 {
  struct timespec cooked_now, now;

@@ -1231,41 +1310,139 @@ handle_reset(CMD_Request *rx_message, CMD_Reply *tx_message)
  LCL_NotifyExternalTimeStep(&now, &cooked_now, 0.0, 0.0);
 }

+/* ================================================== */
+
+static void
+handle_auth_data(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  RPT_AuthReport report;
+  IPAddr ip_addr;
+
+  UTI_IPNetworkToHost(&rx_message->data.auth_data.ip_addr, &ip_addr);
+
+  if (!NSR_GetAuthReport(&ip_addr, &report)) {
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+    return;
+  }
+
+  tx_message->reply = htons(RPY_AUTH_DATA);
+
+  switch (report.mode) {
+    case NTP_AUTH_NONE:
+      tx_message->data.auth_data.mode = htons(RPY_AD_MD_NONE);
+      break;
+    case NTP_AUTH_SYMMETRIC:
+      tx_message->data.auth_data.mode = htons(RPY_AD_MD_SYMMETRIC);
+      break;
+    case NTP_AUTH_NTS:
+      tx_message->data.auth_data.mode = htons(RPY_AD_MD_NTS);
+      break;
+    default:
+      break;
+  }
+
+  tx_message->data.auth_data.key_type = htons(report.key_type);
+  tx_message->data.auth_data.key_id = htonl(report.key_id);
+  tx_message->data.auth_data.key_length = htons(report.key_length);
+  tx_message->data.auth_data.ke_attempts = htons(report.ke_attempts);
+  tx_message->data.auth_data.last_ke_ago = htonl(report.last_ke_ago);
+  tx_message->data.auth_data.cookies = htons(report.cookies);
+  tx_message->data.auth_data.cookie_length = htons(report.cookie_length);
+  tx_message->data.auth_data.nak = htons(report.nak);
+}
+
+/* ================================================== */
+
+static uint16_t
+convert_sd_sel_options(int options)
+{
+  return (options & SRC_SELECT_PREFER ? RPY_SD_OPTION_PREFER : 0) |
+         (options & SRC_SELECT_NOSELECT ? RPY_SD_OPTION_NOSELECT : 0) |
+         (options & SRC_SELECT_TRUST ? RPY_SD_OPTION_TRUST : 0) |
+         (options & SRC_SELECT_REQUIRE ? RPY_SD_OPTION_REQUIRE : 0);
+}
+
+/* ================================================== */
+
+static void
+handle_select_data(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  RPT_SelectReport report;
+
+  if (!SRC_GetSelectReport(ntohl(rx_message->data.select_data.index), &report)) {
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+    return;
+  }
+
+  tx_message->reply = htons(RPY_SELECT_DATA);
+
+  tx_message->data.select_data.ref_id = htonl(report.ref_id);
+  UTI_IPHostToNetwork(&report.ip_addr, &tx_message->data.select_data.ip_addr);
+  tx_message->data.select_data.state_char = report.state_char;
+  tx_message->data.select_data.authentication = report.authentication;
+  tx_message->data.select_data.leap = report.leap;
+  tx_message->data.select_data.conf_options = htons(convert_sd_sel_options(report.conf_options));
+  tx_message->data.select_data.eff_options = htons(convert_sd_sel_options(report.eff_options));
+  tx_message->data.select_data.last_sample_ago = htonl(report.last_sample_ago);
+  tx_message->data.select_data.score = UTI_FloatHostToNetwork(report.score);
+  tx_message->data.select_data.hi_limit = UTI_FloatHostToNetwork(report.hi_limit);
+  tx_message->data.select_data.lo_limit = UTI_FloatHostToNetwork(report.lo_limit);
+}
+
+/* ================================================== */
+
+static void
+handle_modify_selectopts(CMD_Request *rx_message, CMD_Reply *tx_message)
+{
+  int mask, options;
+  uint32_t ref_id;
+  IPAddr ip_addr;
+
+  UTI_IPNetworkToHost(&rx_message->data.modify_select_opts.address, &ip_addr);
+  ref_id = ntohl(rx_message->data.modify_select_opts.ref_id);
+  mask = ntohl(rx_message->data.modify_select_opts.mask);
+  options = convert_addsrc_select_options(ntohl(rx_message->data.modify_select_opts.options));
+
+  if (!SRC_ModifySelectOptions(&ip_addr, ref_id, options, mask))
+    tx_message->status = htons(STT_NOSUCHSOURCE);
+}
+
 /* ================================================== */
 /* Read a packet and process it */

 static void
 read_from_cmd_socket(int sock_fd, int event, void *anything)
 {
-  SCK_Message sck_message;
+  SCK_Message *sck_message;
  CMD_Request rx_message;
  CMD_Reply tx_message;
  IPAddr loopback_addr, remote_ip;
  int read_length, expected_length;
  int localhost, allowed, log_index;
-  unsigned short rx_command;
+  uint16_t rx_command;
  struct timespec now, cooked_now;

-  if (!SCK_ReceiveMessage(sock_fd, &sck_message, 0))
+  sck_message = SCK_ReceiveMessage(sock_fd, 0);
+  if (!sck_message)
    return;

-  read_length = sck_message.length;
+  read_length = sck_message->length;

  /* Get current time cheaply */
  SCH_GetLastEventTime(&cooked_now, NULL, &now);

  /* Check if it's from localhost (127.0.0.1, ::1, or Unix domain),
     or an authorised address */
-  switch (sck_message.addr_type) {
+  switch (sck_message->addr_type) {
    case SCK_ADDR_IP:
      assert(sock_fd == sock_fd4 || sock_fd == sock_fd6);
-      remote_ip = sck_message.remote_addr.ip.ip_addr;
+      remote_ip = sck_message->remote_addr.ip.ip_addr;
      SCK_GetLoopbackIPAddress(remote_ip.family, &loopback_addr);
      localhost = UTI_CompareIPs(&remote_ip, &loopback_addr, NULL) == 0;

      if (!localhost && !ADF_IsAllowed(access_auth_table, &remote_ip)) {
        DEBUG_LOG("Unauthorised host %s",
-                  UTI_IPSockAddrToString(&sck_message.remote_addr.ip));
+                  UTI_IPSockAddrToString(&sck_message->remote_addr.ip));
        return;
      }

@@ -1291,7 +1468,7 @@ read_from_cmd_socket(int sock_fd, int event, void *anything)
    return;
  }

-  memcpy(&rx_message, sck_message.data, read_length);
+  memcpy(&rx_message, sck_message->data, read_length);

  if (rx_message.pkt_type != PKT_TYPE_CMD_REQUEST ||
      rx_message.res1 != 0 ||
@@ -1300,11 +1477,11 @@ read_from_cmd_socket(int sock_fd, int event, void *anything)
    return;
  }

-  log_index = CLG_LogCommandAccess(&remote_ip, &cooked_now);
+  log_index = CLG_LogServiceAccess(CLG_CMDMON, &remote_ip, &cooked_now);

  /* Don't reply to all requests from hosts other than localhost if the rate
     is excessive */
-  if (!localhost && log_index >= 0 && CLG_LimitCommandResponseRate(log_index)) {
+  if (!localhost && log_index >= 0 && CLG_LimitServiceRate(CLG_CMDMON, log_index)) {
      DEBUG_LOG("Command packet discarded to limit response rate");
      return;
  }
@@ -1313,8 +1490,8 @@ read_from_cmd_socket(int sock_fd, int event, void *anything)
  rx_command = ntohs(rx_message.command);

  memset(&tx_message, 0, sizeof (tx_message));
-  sck_message.data = &tx_message;
-  sck_message.length = 0;
+  sck_message->data = &tx_message;
+  sck_message->length = 0;

  tx_message.version = PROTO_VERSION_NUMBER;
  tx_message.pkt_type = PKT_TYPE_CMD_REPLY;
@@ -1329,7 +1506,7 @@ read_from_cmd_socket(int sock_fd, int event, void *anything)

    if (rx_message.version >= PROTO_VERSION_MISMATCH_COMPAT_SERVER) {
      tx_message.status = htons(STT_BADPKTVERSION);
-      transmit_reply(sock_fd, &sck_message);
+      transmit_reply(sock_fd, read_length, sck_message);
    }
    return;
  }
@@ -1339,7 +1516,7 @@ read_from_cmd_socket(int sock_fd, int event, void *anything)
    DEBUG_LOG("Command packet has invalid command %d", rx_command);

    tx_message.status = htons(STT_INVALID);
-    transmit_reply(sock_fd, &sck_message);
+    transmit_reply(sock_fd, read_length, sck_message);
    return;
  }

@@ -1348,7 +1525,7 @@ read_from_cmd_socket(int sock_fd, int event, void *anything)
              expected_length);

    tx_message.status = htons(STT_BADPKTLENGTH);
-    transmit_reply(sock_fd, &sck_message);
+    transmit_reply(sock_fd, read_length, sck_message);
    return;
  }

@@ -1382,6 +1559,8 @@ read_from_cmd_socket(int sock_fd, int event, void *anything)
    }

    if (allowed) {
+      LOG_SetContext(LOGC_Command);
+
      switch(rx_command) {
        case REQ_NULL:
          /* Do nothing */
@@ -1516,7 +1695,7 @@ read_from_cmd_socket(int sock_fd, int event, void *anything)
          handle_dfreq(&rx_message, &tx_message);
          break;

-        case REQ_DOFFSET:
+        case REQ_DOFFSET2:
          handle_doffset(&rx_message, &tx_message);
          break;

@@ -1548,7 +1727,7 @@ read_from_cmd_socket(int sock_fd, int event, void *anything)
          handle_cyclelogs(&rx_message, &tx_message);
          break;

-        case REQ_CLIENT_ACCESSES_BY_INDEX2:
+        case REQ_CLIENT_ACCESSES_BY_INDEX3:
          handle_client_accesses_by_index(&rx_message, &tx_message);
          break;

@@ -1608,8 +1787,24 @@ read_from_cmd_socket(int sock_fd, int event, void *anything)
          handle_ntp_source_name(&rx_message, &tx_message);
          break;

-        case REQ_RESET:
-          handle_reset(&rx_message, &tx_message);
+        case REQ_RESET_SOURCES:
+          handle_reset_sources(&rx_message, &tx_message);
+          break;
+
+        case REQ_AUTH_DATA:
+          handle_auth_data(&rx_message, &tx_message);
+          break;
+
+        case REQ_SELECT_DATA:
+          handle_select_data(&rx_message, &tx_message);
+          break;
+
+        case REQ_RELOAD_SOURCES:
+          handle_reload_sources(&rx_message, &tx_message);
+          break;
+
+        case REQ_MODIFY_SELECTOPTS:
+          handle_modify_selectopts(&rx_message, &tx_message);
          break;

        default:
@@ -1617,25 +1812,15 @@ read_from_cmd_socket(int sock_fd, int event, void *anything)
          tx_message.status = htons(STT_FAILED);
          break;
      }
+
+      LOG_UnsetContext(LOGC_Command);
    } else {
      tx_message.status = htons(STT_UNAUTH);
    }
  }

  /* Transmit the response */
-  {
-    /* Include a simple way to lose one message in three to test resend */
-
-    static int do_it=1;
-
-    if (do_it) {
-      transmit_reply(sock_fd, &sck_message);
-    }
-
-#if 0
-    do_it = ((do_it + 1) % 3);
-#endif
-  }
+  transmit_reply(sock_fd, read_length, sck_message);
 }

 /* ================================================== */
@@ -1662,6 +1847,9 @@ CAM_AddAccessRestriction(IPAddr *ip_addr, int subnet_bits, int allow, int all)
  if (status == ADF_BADSUBNET) {
    return 0;
  } else if (status == ADF_SUCCESS) {
+    LOG(LOG_GetContextSeverity(LOGC_Command), "%s%s %s access from %s",
+        allow ? "Allowed" : "Denied", all ? " all" : "", "command",
+        UTI_IPSubnetToString(ip_addr, subnet_bits));
    return 1;
  } else {
    return 0;
--- a/cmdmon.h
+++ b/cmdmon.h
@@ -29,7 +29,7 @@

 #include "addressing.h"

-extern void CAM_Initialise(int family);
+extern void CAM_Initialise(void);

 extern void CAM_Finalise(void);

--- a/cmdparse.c
+++ b/cmdparse.c
@@ -3,7 +3,7 @@

 **********************************************************************
 * Copyright (C) Richard P. Curnow  1997-2003
- * Copyright (C) Miroslav Lichvar  2013-2014, 2016
+ * Copyright (C) Miroslav Lichvar  2013-2014, 2016, 2021
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
@@ -43,7 +43,8 @@ int
 CPS_ParseNTPSourceAdd(char *line, CPS_NTP_Source *src)
 {
  char *hostname, *cmd;
-  int n;
+  uint32_t ef_type;
+  int n, sel_option;
  
  src->port = SRC_DEFAULT_PORT;
  src->params.minpoll = SRC_DEFAULT_MINPOLL;
@@ -64,10 +65,14 @@ CPS_ParseNTPSourceAdd(char *line, CPS_NTP_Source *src)
  src->params.sel_options = 0;
  src->params.nts = 0;
  src->params.nts_port = SRC_DEFAULT_NTSPORT;
+  src->params.copy = 0;
+  src->params.ext_fields = 0;
  src->params.authkey = INACTIVE_AUTHKEY;
+  src->params.cert_set = SRC_DEFAULT_CERTSET;
  src->params.max_delay = SRC_DEFAULT_MAXDELAY;
  src->params.max_delay_ratio = SRC_DEFAULT_MAXDELAYRATIO;
  src->params.max_delay_dev_ratio = SRC_DEFAULT_MAXDELAYDEVRATIO;
+  src->params.max_delay_quant = 0.0;
  src->params.min_delay = 0.0;
  src->params.asymmetry = SRC_DEFAULT_ASYMMETRY;
  src->params.offset = 0.0;
@@ -90,18 +95,15 @@ CPS_ParseNTPSourceAdd(char *line, CPS_NTP_Source *src)
      src->params.auto_offline = 1;
    } else if (!strcasecmp(cmd, "burst")) {
      src->params.burst = 1;
+    } else if (!strcasecmp(cmd, "copy")) {
+      src->params.copy = 1;
    } else if (!strcasecmp(cmd, "iburst")) {
      src->params.iburst = 1;
    } else if (!strcasecmp(cmd, "offline")) {
      src->params.connectivity = SRC_OFFLINE;
-    } else if (!strcasecmp(cmd, "noselect")) {
-      src->params.sel_options |= SRC_SELECT_NOSELECT;
-    } else if (!strcasecmp(cmd, "prefer")) {
-      src->params.sel_options |= SRC_SELECT_PREFER;
-    } else if (!strcasecmp(cmd, "require")) {
-      src->params.sel_options |= SRC_SELECT_REQUIRE;
-    } else if (!strcasecmp(cmd, "trust")) {
-      src->params.sel_options |= SRC_SELECT_TRUST;
+    } else if (!strcasecmp(cmd, "certset")) {
+      if (sscanf(line, "%"SCNu32"%n", &src->params.cert_set, &n) != 1)
+        return 0;
    } else if (!strcasecmp(cmd, "key")) {
      if (sscanf(line, "%"SCNu32"%n", &src->params.authkey, &n) != 1 ||
          src->params.authkey == INACTIVE_AUTHKEY)
@@ -109,6 +111,16 @@ CPS_ParseNTPSourceAdd(char *line, CPS_NTP_Source *src)
    } else if (!strcasecmp(cmd, "asymmetry")) {
      if (sscanf(line, "%lf%n", &src->params.asymmetry, &n) != 1)
        return 0;
+    } else if (!strcasecmp(cmd, "extfield")) {
+      if (sscanf(line, "%"SCNx32"%n", &ef_type, &n) != 1)
+        return 0;
+      switch (ef_type) {
+        case NTP_EF_EXP1:
+          src->params.ext_fields |= NTP_EF_FLAG_EXP1;
+          break;
+        default:
+          return 0;
+      }
    } else if (!strcasecmp(cmd, "filter")) {
      if (sscanf(line, "%d%n", &src->params.filter_length, &n) != 1)
        return 0;
@@ -121,6 +133,9 @@ CPS_ParseNTPSourceAdd(char *line, CPS_NTP_Source *src)
    } else if (!strcasecmp(cmd, "maxdelaydevratio")) {
      if (sscanf(line, "%lf%n", &src->params.max_delay_dev_ratio, &n) != 1)
        return 0;
+    } else if (!strcasecmp(cmd, "maxdelayquant")) {
+      if (sscanf(line, "%lf%n", &src->params.max_delay_quant, &n) != 1)
+        return 0;
    } else if (!strcasecmp(cmd, "maxpoll")) {
      if (sscanf(line, "%d%n", &src->params.maxpoll, &n) != 1)
        return 0;
@@ -151,7 +166,7 @@ CPS_ParseNTPSourceAdd(char *line, CPS_NTP_Source *src)
      if (sscanf(line, "%lf%n", &src->params.offset, &n) != 1)
        return 0;
    } else if (!strcasecmp(cmd, "port")) {
-      if (sscanf(line, "%hu%n", &src->port, &n) != 1)
+      if (sscanf(line, "%d%n", &src->port, &n) != 1)
        return 0;
    } else if (!strcasecmp(cmd, "polltarget")) {
      if (sscanf(line, "%d%n", &src->params.poll_target, &n) != 1)
@@ -164,6 +179,8 @@ CPS_ParseNTPSourceAdd(char *line, CPS_NTP_Source *src)
        return 0;
    } else if (!strcasecmp(cmd, "xleave")) {
      src->params.interleaved = 1;
+    } else if ((sel_option = CPS_GetSelectOption(cmd)) != 0) {
+      src->params.sel_options |= sel_option;
    } else {
      return 0;
    }
@@ -174,6 +191,102 @@ CPS_ParseNTPSourceAdd(char *line, CPS_NTP_Source *src)

 /* ================================================== */

+int
+CPS_GetSelectOption(char *option)
+{
+  if (!strcasecmp(option, "noselect")) {
+    return SRC_SELECT_NOSELECT;
+  } else if (!strcasecmp(option, "prefer")) {
+    return SRC_SELECT_PREFER;
+  } else if (!strcasecmp(option, "require")) {
+    return SRC_SELECT_REQUIRE;
+  } else if (!strcasecmp(option, "trust")) {
+    return SRC_SELECT_TRUST;
+  }
+  return 0;
+}
+
+/* ================================================== */
+
+int
+CPS_ParseAllowDeny(char *line, int *all, IPAddr *ip, int *subnet_bits)
+{
+  char *p, *net, *slash;
+  uint32_t a, b, c;
+  int bits, len, n;
+
+  p = CPS_SplitWord(line);
+
+  if (strcmp(line, "all") == 0) {
+    *all = 1;
+    net = p;
+    p = CPS_SplitWord(p);
+  } else {
+    *all = 0;
+    net = line;
+  }
+
+  /* Make sure there are no other arguments */
+  if (*p)
+    return 0;
+
+  /* No specified address or network means all IPv4 and IPv6 addresses */
+  if (!*net) {
+    ip->family = IPADDR_UNSPEC;
+    *subnet_bits = 0;
+    return 1;
+  }
+
+  slash = strchr(net, '/');
+  if (slash) {
+    if (sscanf(slash + 1, "%d%n", &bits, &len) != 1 || slash[len + 1] || bits < 0)
+      return 0;
+    *slash = '\0';
+  } else {
+    bits = -1;
+  }
+
+  if (UTI_StringToIP(net, ip)) {
+    if (bits >= 0)
+      *subnet_bits = bits;
+    else
+      *subnet_bits = ip->family == IPADDR_INET6 ? 128 : 32;
+    return 1;
+  }
+
+  /* Check for a shortened IPv4 network notation using only 1, 2, or 3 decimal
+     numbers.  This is different than the numbers-and-dots notation accepted
+     by inet_aton()! */
+
+  a = b = c = 0;
+  n = sscanf(net, "%"PRIu32"%n.%"PRIu32"%n.%"PRIu32"%n", &a, &len, &b, &len, &c, &len);
+
+  if (n > 0 && !net[len]) {
+    if (a > 255 || b > 255 || c > 255)
+      return 0;
+
+    ip->family = IPADDR_INET4;
+    ip->addr.in4 = (a << 24) | (b << 16) | (c << 8);
+
+    if (bits >= 0)
+      *subnet_bits = bits;
+    else
+      *subnet_bits = n * 8;
+
+    return 1;
+  }
+
+  /* The last possibility is a hostname */
+  if (bits < 0 && DNS_Name2IPAddress(net, ip, 1) == DNS_Success) {
+    *subnet_bits = ip->family == IPADDR_INET6 ? 128 : 32;
+    return 1;
+  }
+
+  return 0;
+}
+
+/* ================================================== */
+
 int
 CPS_ParseLocal(char *line, int *stratum, int *orphan, double *distance)
 {
@@ -294,3 +407,19 @@ CPS_ParseKey(char *line, uint32_t *id, const char **type, char **key)

  return 1;
 }
+
+/* ================================================== */
+
+int
+CPS_ParseRefid(char *line, uint32_t *ref_id)
+{
+  int i;
+
+  for (i = *ref_id = 0; line[i] && !isspace((unsigned char)line[i]); i++) {
+    if (i >= 4)
+      return 0;
+    *ref_id |= (uint32_t)line[i] << (24 - i * 8);
+  }
+
+  return i;
+}
--- a/cmdparse.h
+++ b/cmdparse.h
@@ -32,13 +32,19 @@

 typedef struct {
  char *name;
-  unsigned short port;
+  int port;
  SourceParameters params;
 } CPS_NTP_Source;

 /* Parse a command to add an NTP server or peer */
 extern int CPS_ParseNTPSourceAdd(char *line, CPS_NTP_Source *src);
  
+/* Get an NTP/refclock select option */
+extern int CPS_GetSelectOption(char *option);
+
+/* Parse a command to allow/deny access */
+extern int CPS_ParseAllowDeny(char *line, int *all, IPAddr *ip, int *subnet_bits);
+
 /* Parse a command to enable local reference */
 extern int CPS_ParseLocal(char *line, int *stratum, int *orphan, double *distance);

@@ -51,4 +57,7 @@ extern char *CPS_SplitWord(char *line);
 /* Parse a key from keyfile */
 extern int CPS_ParseKey(char *line, uint32_t *id, const char **type, char **key);

+/* Parse a refclock reference ID (returns number of characters) */
+extern int CPS_ParseRefid(char *line, uint32_t *ref_id);
+
 #endif /* GOT_CMDPARSE_H */
--- a/conf.c
+++ b/conf.c
--- a/conf.h
+++ b/conf.h
@@ -30,10 +30,13 @@

 #include "addressing.h"
 #include "reference.h"
+#include "sources.h"

 extern void CNF_Initialise(int restarted, int client_only);
 extern void CNF_Finalise(void);

+extern void CNF_EnablePrint(void);
+
 extern char *CNF_GetRtcDevice(void);

 extern void CNF_ReadFile(const char *filename);
@@ -41,11 +44,15 @@ extern void CNF_ParseLine(const char *filename, int number, char *line);

 extern void CNF_CreateDirs(uid_t uid, gid_t gid);

+extern void CNF_CheckReadOnlyAccess(void);
+
 extern void CNF_AddInitSources(void);
 extern void CNF_AddSources(void);
 extern void CNF_AddBroadcasts(void);
 extern void CNF_AddRefclocks(void);

+extern void CNF_ReloadSources(void);
+
 extern int CNF_GetAcquisitionPort(void);
 extern int CNF_GetNTPPort(void);
 extern char *CNF_GetDriftFile(void);
@@ -53,6 +60,7 @@ extern char *CNF_GetLogDir(void);
 extern char *CNF_GetDumpDir(void);
 extern int CNF_GetLogBanner(void);
 extern int CNF_GetLogMeasurements(int *raw);
+extern int CNF_GetLogSelection(void);
 extern int CNF_GetLogStatistics(void);
 extern int CNF_GetLogTracking(void);
 extern int CNF_GetLogRtc(void);
@@ -74,7 +82,11 @@ extern void CNF_GetFallbackDrifts(int *min, int *max);
 extern void CNF_GetBindAddress(int family, IPAddr *addr);
 extern void CNF_GetBindAcquisitionAddress(int family, IPAddr *addr);
 extern void CNF_GetBindCommandAddress(int family, IPAddr *addr);
+extern char *CNF_GetBindNtpInterface(void);
+extern char *CNF_GetBindAcquisitionInterface(void);
+extern char *CNF_GetBindCommandInterface(void);
 extern char *CNF_GetBindCommandPath(void);
+extern int CNF_GetNtpDscp(void);
 extern char *CNF_GetNtpSigndSocket(void);
 extern char *CNF_GetPidFile(void);
 extern REF_LeapMode CNF_GetLeapSecMode(void);
@@ -86,7 +98,9 @@ extern double CNF_GetMaxClockError(void);
 extern double CNF_GetMaxDrift(void);
 extern double CNF_GetCorrectionTimeRatio(void);
 extern double CNF_GetMaxSlewRate(void);
+extern double CNF_GetClockPrecision(void);

+extern SRC_AuthSelectMode CNF_GetAuthSelectMode(void);
 extern double CNF_GetMaxDistance(void);
 extern double CNF_GetMaxJitter(void);
 extern double CNF_GetReselectDistance(void);
@@ -101,6 +115,7 @@ extern int CNF_GetSchedPriority(void);
 extern int CNF_GetLockMemory(void);

 extern int CNF_GetNTPRateLimit(int *interval, int *burst, int *leak);
+extern int CNF_GetNtsRateLimit(int *interval, int *burst, int *leak);
 extern int CNF_GetCommandRateLimit(int *interval, int *burst, int *leak);
 extern void CNF_GetSmooth(double *max_freq, double *max_wander, int *leap_only);
 extern void CNF_GetTempComp(char **file, double *interval, char **point_file, double *T0, double *k0, double *k1, double *k2);
@@ -122,12 +137,14 @@ typedef enum {
  CNF_HWTS_RXFILTER_ANY,
  CNF_HWTS_RXFILTER_NONE,
  CNF_HWTS_RXFILTER_NTP,
+  CNF_HWTS_RXFILTER_PTP,
  CNF_HWTS_RXFILTER_ALL,
 } CNF_HwTs_RxFilter;

 typedef struct {
  char *name;
  int minpoll;
+  int maxpoll;
  int min_samples;
  int max_samples;
  int nocrossts;
@@ -138,16 +155,22 @@ typedef struct {
 } CNF_HwTsInterface;

 extern int CNF_GetHwTsInterface(unsigned int index, CNF_HwTsInterface **iface);
+extern double CNF_GetHwTsTimeout(void);

-extern char *CNF_GetNtsCacheDir(void);
-extern char *CNF_GetNtsServerCertFile(void);
-extern char *CNF_GetNtsServerKeyFile(void);
+extern int CNF_GetPtpPort(void);
+
+extern int CNF_GetRefresh(void);
+
+extern char *CNF_GetNtsDumpDir(void);
+extern char *CNF_GetNtsNtpServer(void);
+extern int CNF_GetNtsServerCertAndKeyFiles(const char ***certs, const char ***keys);
 extern int CNF_GetNtsServerPort(void);
 extern int CNF_GetNtsServerProcesses(void);
 extern int CNF_GetNtsServerConnections(void);
 extern int CNF_GetNtsRefresh(void);
 extern int CNF_GetNtsRotate(void);
-extern char *CNF_GetNtsTrustedCertFile(void);
+extern int CNF_GetNtsTrustedCertsPaths(const char ***paths, uint32_t **ids);
 extern int CNF_GetNoSystemCert(void);
+extern int CNF_GetNoCertTimeCheck(void);

 #endif /* GOT_CONF_H */
--- a/234
+++ b/234
@@ -5,7 +5,7 @@
 #
 # Copyright (C) Richard P. Curnow  1997-2003
 # Copyright (C) Bryan Christianson  2016
-# Copyright (C) Miroslav Lichvar  2009, 2012-2018
+# Copyright (C) Miroslav Lichvar  2009, 2012-2022
 # Copyright (C) Stefan R. Filipek  2019
 #
 # =======================================================================
@@ -33,13 +33,13 @@ test_code () {
    echo "int main(int argc, char **argv) {"
    echo "$code"
    echo "return 0; }"
-  ) > docheck.c
+  ) > conftest.c

-  echo "docheck.c:" >> config.log
-  cat docheck.c >> config.log
-  echo $MYCC $MYCFLAGS $MYCPPFLAGS $cflags -o docheck docheck.c $ldflags \
+  echo "conftest.c:" >> config.log
+  cat conftest.c >> config.log
+  echo $MYCC $MYCFLAGS $MYCPPFLAGS $cflags -o conftest conftest.c $ldflags \
    $MYLDFLAGS >> config.log
-  $MYCC $MYCFLAGS $MYCPPFLAGS $cflags -o docheck docheck.c $ldflags \
+  $MYCC $MYCFLAGS $MYCPPFLAGS $cflags -o conftest conftest.c $ldflags \
    $MYLDFLAGS >> config.log 2>&1

  if [ $? -eq 0 ]
@@ -50,7 +50,7 @@ test_code () {
    echo "No"
    result=1
  fi
-  rm -f docheck.c docheck
+  rm -f conftest.c conftest
  echo >> config.log
  return $result
 }
@@ -108,11 +108,7 @@ for instance \`--prefix=$HOME'.

 For better control, use the options below.
  --disable-readline     Disable line editing support
-  --without-readline     Don't use GNU readline even if it is available
  --without-editline     Don't use editline even if it is available
-  --with-readline-includes=DIR Specify where readline include directory is
-  --with-readline-library=DIR Specify where readline lib directory is
-  --with-ncurses-library=DIR Specify where ncurses lib directory is
  --disable-sechash      Disable support for hashes other than MD5
  --without-nettle       Don't use nettle even if it is available
  --without-nss          Don't use NSS even if it is available
@@ -132,6 +128,7 @@ For better control, use the options below.
  --without-seccomp      Don't use seccomp even if it is available
  --disable-asyncdns     Disable asynchronous name resolving
  --disable-forcednsretry Don't retry on permanent DNS error
+  --without-aes-gcm-siv  Don't use AES-GCM-SIV for NTS even if it is available
  --without-clock-gettime Don't use clock_gettime() even if it is available
  --disable-timestamping Disable support for SW/HW timestamping
  --enable-ntp-signd     Enable support for MS-SNTP authentication in Samba
@@ -225,7 +222,6 @@ feat_cmdmon=1
 feat_ntp=1
 feat_refclock=1
 feat_readline=1
-try_readline=1
 try_editline=1
 feat_sechash=1
 try_nettle=1
@@ -241,9 +237,6 @@ try_clockctl=0
 feat_scfilter=0
 try_seccomp=-1
 priv_ops=""
-readline_lib=""
-readline_inc=""
-ncurses_lib=""
 feat_ipv6=1
 feat_phc=1
 try_phc=0
@@ -252,7 +245,9 @@ try_setsched=0
 try_lockmem=0
 feat_asyncdns=1
 feat_forcednsretry=1
+try_aes_gcm_siv=1
 try_clock_gettime=1
+try_arc4random=1
 try_recvmmsg=1
 feat_timestamping=1
 try_timestamping=0
@@ -274,21 +269,9 @@ do
    --disable-readline )
      feat_readline=0
    ;;
-    --without-readline )
-      try_readline=0
-    ;;
    --without-editline )
      try_editline=0
    ;;
-    --with-readline-library=* )
-      readline_lib=-L`echo $option | sed -e 's/^.*=//;'`
-    ;;
-    --with-readline-includes=* )
-      readline_inc=-I`echo $option | sed -e 's/^.*=//;'`
-    ;;
-    --with-ncurses-library=* )
-      ncurses_lib=-L`echo $option | sed -e 's/^.*=//;'`
-    ;;
    --prefix=* | --install_prefix=* )
      SETPREFIX=`echo $option | sed -e 's/[^=]*=//;'`
    ;;
@@ -364,6 +347,9 @@ do
    --disable-forcednsretry)
      feat_forcednsretry=0
    ;;
+    --without-aes-gcm-siv)
+      try_aes_gcm_siv=0
+    ;;
    --without-clock-gettime)
      try_clock_gettime=0
    ;;
@@ -441,6 +427,7 @@ case $OPERATINGSYSTEM in
        try_setsched=1
        try_lockmem=1
        try_phc=1
+        try_arc4random=0
        add_def LINUX
        echo "Configuring for " $SYSTEM
    ;;
@@ -487,7 +474,7 @@ case $OPERATINGSYSTEM in
    ;;
    SunOS)
        EXTRA_OBJECTS="sys_generic.o sys_solaris.o sys_timex.o sys_posix.o"
-        LIBS="$LIBS -lsocket -lnsl -lresolv"
+        LIBS="$LIBS -lsocket -lnsl -lkvm -lelf -lresolv"
        try_setsched=1
        try_lockmem=1
        add_def SOLARIS
@@ -499,7 +486,7 @@ case $OPERATINGSYSTEM in
          add_def FEAT_PRIVDROP
          priv_ops="ADJUSTTIMEX SETTIME BINDSOCKET"
        fi
-        echo "Configuring for Solaris (" $SYSTEM "SunOS version" $VERSION ")" 
+        echo "Configuring for illumos (" $SYSTEM "SunOS version" $VERSION ")"
    ;;                                                                        
    * )
        echo "error: $SYSTEM is not supported (yet?)"
@@ -583,6 +570,13 @@ if [ "x$MYCFLAGS" = "x" ]; then
  fi
 fi

+TESTCFLAGS="-fwrapv"
+if test_code '-fwrapv' '' "$TESTCFLAGS" '' ''; then
+  GETDATE_CFLAGS="-fwrapv"
+else
+  GETDATE_CFLAGS=""
+fi
+
 if [ "x$MYCC" = "xgcc" ] || [ "x$MYCC" = "xclang" ]; then
  MYCFLAGS="$MYCFLAGS -Wmissing-prototypes -Wall"
 fi
@@ -657,6 +651,7 @@ if [ $feat_ipv6 = "1" ] && \
    struct sockaddr_in6 n;
    char p[100];
    n.sin6_addr = in6addr_any;
+    n.sin6_scope_id = 0;
    return !inet_ntop(AF_INET6, &n.sin6_addr.s6_addr, p, sizeof(p));'
 then
  add_def FEAT_IPV6
@@ -674,14 +669,28 @@ then
  fi
 fi

+if ! test_code 'O_NOFOLLOW flag' 'sys/types.h sys/stat.h fcntl.h' '' "$LIBS" \
+  'return open("/dev/null", O_NOFOLLOW);'
+then
+  if test_code 'O_NOFOLLOW flag with _GNU_SOURCE' 'sys/types.h sys/stat.h fcntl.h' \
+    '-D_GNU_SOURCE' "$LIBS" \
+    'return open("/dev/null", O_NOFOLLOW);'
+  then
+    add_def _GNU_SOURCE
+  else
+    echo "error: open() does not support O_NOFOLLOW flag"
+    exit 1
+  fi
+fi
+
 if [ $try_clock_gettime = "1" ]; then
  if test_code 'clock_gettime()' 'time.h' '' '' \
-    'clock_gettime(CLOCK_REALTIME, NULL);'
+    'clock_gettime(CLOCK_REALTIME, (void *)1);'
  then
    add_def HAVE_CLOCK_GETTIME
  else
    if test_code 'clock_gettime() in -lrt' 'time.h' '' '-lrt' \
-      'clock_gettime(CLOCK_REALTIME, NULL);'
+      'clock_gettime(CLOCK_REALTIME, (void *)1);'
    then
      add_def HAVE_CLOCK_GETTIME
      EXTRA_LIBS="$EXTRA_LIBS -lrt"
@@ -689,10 +698,11 @@ if [ $try_clock_gettime = "1" ]; then
  fi
 fi

-if test_code 'getaddrinfo()' 'sys/types.h sys/socket.h netdb.h' '' "$LIBS" \
+if ! test_code 'getaddrinfo()' 'sys/types.h sys/socket.h netdb.h' '' "$LIBS" \
  'return getaddrinfo(0, 0, 0, 0);'
 then
-  add_def HAVE_GETADDRINFO
+  echo "error: getaddrinfo() not found"
+  exit 1
 fi

 if [ $feat_asyncdns = "1" ] && \
@@ -706,13 +716,16 @@ then
  use_pthread=1
 fi

-if test_code 'arc4random_buf()' 'stdlib.h' '' '' 'arc4random_buf(NULL, 0);'; then
+if [ $try_arc4random = "1" ] && \
+  test_code 'arc4random_buf()' 'stdlib.h' '' '' \
+    'arc4random_buf((void *)1, 1);'
+then
  add_def HAVE_ARC4RANDOM
-fi
-
-if test_code 'getrandom()' 'stdlib.h sys/random.h' '' '' \
-    'return getrandom(NULL, 256, 0);'; then
-  add_def HAVE_GETRANDOM
+else
+  if test_code 'getrandom()' 'stdlib.h sys/random.h' '' '' \
+      'return getrandom((void *)1, 1, 0);'; then
+    add_def HAVE_GETRANDOM
+  fi
 fi

 RECVMMSG_CODE='
@@ -803,10 +816,12 @@ if [ $feat_scfilter = "1" ] && [ $try_seccomp = "1" ] && \
    'seccomp_init(SCMP_ACT_KILL);'
 then
  add_def FEAT_SCFILTER
-  # NAME2IPADDRESS shouldn't be enabled with other operations as the helper
-  # process works on one request at the time and the async resolver could
-  # block the main thread
-  priv_ops="NAME2IPADDRESS RELOADDNS"
+  if [ $feat_ntp = "1" ]; then
+    # NAME2IPADDRESS shouldn't be enabled together with a privops operation
+    # used by the main thread as the helper process works on one request at
+    # a time and the async resolver would block the main thread
+    priv_ops="NAME2IPADDRESS RELOADDNS"
+  fi
  EXTRA_LIBS="$EXTRA_LIBS -lseccomp"
 fi

@@ -875,37 +890,11 @@ fi
 READLINE_LINK=""
 if [ $feat_readline = "1" ]; then
  if [ $try_editline = "1" ]; then
-    if test_code editline 'stdio.h editline/readline.h' \
-      "$readline_inc" "$readline_lib -ledit" \
+    if test_code editline 'stdio.h editline/readline.h' '' '-ledit' \
      'add_history(readline("prompt"));'
    then
      add_def FEAT_READLINE
-      add_def USE_EDITLINE
-      MYCPPFLAGS="$MYCPPFLAGS $readline_inc"
-      READLINE_LINK="$readline_lib -ledit"
-    fi
-  fi
-
-  if [ "x$READLINE_LINK" = "x" ] && [ $try_readline = "1" ]; then
-    if test_code readline 'stdio.h readline/readline.h readline/history.h' \
-      "$readline_inc" "$readline_lib -lreadline" \
-      'add_history(readline("prompt"));'
-    then
-      add_def FEAT_READLINE
-      MYCPPFLAGS="$MYCPPFLAGS $readline_inc"
-      READLINE_LINK="$readline_lib -lreadline"
-    fi
-  fi
-
-  if [ "x$READLINE_LINK" = "x" ] && [ $try_readline = "1" ]; then
-    if test_code 'readline with -lncurses' \
-      'stdio.h readline/readline.h readline/history.h' \
-      "$readline_inc" "$readline_lib $ncurses_lib -lreadline -lncurses" \
-      'add_history(readline("prompt"));'
-    then
-      add_def FEAT_READLINE
-      MYCPPFLAGS="$MYCPPFLAGS $readline_inc"
-      READLINE_LINK="$readline_lib $ncurses_lib -lreadline -lncurses"
+      READLINE_LINK="-ledit"
    fi
  fi

@@ -928,7 +917,7 @@ if [ $feat_sechash = "1" ] && [ "x$HASH_LINK" = "x" ]  && [ $try_nettle = "1" ];
    add_def FEAT_SECHASH

    if test_code 'CMAC in nettle' 'nettle/cmac.h' "$test_cflags" "$test_link" \
-      'cmac128_update(NULL, NULL, NULL, 0, NULL);'
+      'cmac128_update((void *)1, (void *)2, (void *)3, 1, (void *)4);'
    then
      add_def HAVE_CMAC
      EXTRA_OBJECTS="$EXTRA_OBJECTS cmac_nettle.o"
@@ -939,7 +928,7 @@ fi

 if [ $feat_sechash = "1" ] && [ "x$HASH_LINK" = "x" ]  && [ $try_nss = "1" ]; then
  test_cflags="`pkg_config --cflags nss`"
-  test_link="`pkg_config --libs-only-L nss` -lfreebl3"
+  test_link="`pkg_config --libs-only-L nss` -lfreebl3 -lnssutil3"
  if test_code 'NSS' 'nss.h hasht.h nsslowhash.h' \
    "$test_cflags" "$test_link" \
    'NSSLOWHASH_Begin(NSSLOWHASH_NewContext(NSSLOW_Init(), HASH_AlgSHA512));'
@@ -953,7 +942,7 @@ fi

 if [ $feat_sechash = "1" ] && [ "x$HASH_LINK" = "x" ] && [ $try_tomcrypt = "1" ]; then
  if test_code 'tomcrypt' 'tomcrypt.h' '-I/usr/include/tomcrypt' '-ltomcrypt' \
-    'hash_memory_multi(find_hash("md5"), NULL, NULL, NULL, 0, NULL, 0);'
+    'hash_memory_multi(find_hash("md5"), (void *)1, (void *)2, (void *)3, 1, (void *)4, 1);'
  then
    HASH_OBJ="hash_tomcrypt.o"
    HASH_LINK="-ltomcrypt"
@@ -962,35 +951,89 @@ if [ $feat_sechash = "1" ] && [ "x$HASH_LINK" = "x" ] && [ $try_tomcrypt = "1" ]
  fi
 fi

+if [ $feat_sechash = "1" ] && [ "x$HASH_LINK" = "x" ] && [ $try_gnutls = "1" ]; then
+  test_cflags="`pkg_config --cflags gnutls`"
+  test_link="`pkg_config --libs gnutls`"
+  if test_code 'gnutls' 'gnutls/crypto.h' \
+    "$test_cflags" "$test_link" '
+      return gnutls_hash((void *)1, (void *)2, 1);'
+  then
+    HASH_OBJ="hash_gnutls.o"
+    HASH_LINK="$test_link"
+    MYCPPFLAGS="$MYCPPFLAGS $test_cflags"
+    add_def FEAT_SECHASH
+
+    if test_code 'CMAC in gnutls' 'gnutls/crypto.h' "$test_cflags" "$test_link" \
+      'return gnutls_hmac_init((void *)1, GNUTLS_MAC_AES_CMAC_128, (void *)2, 0);'
+    then
+      add_def HAVE_CMAC
+      EXTRA_OBJECTS="$EXTRA_OBJECTS cmac_gnutls.o"
+      EXTRA_CLI_OBJECTS="$EXTRA_CLI_OBJECTS cmac_gnutls.o"
+    fi
+  fi
+fi
+
 EXTRA_OBJECTS="$EXTRA_OBJECTS $HASH_OBJ"
 EXTRA_CLI_OBJECTS="$EXTRA_CLI_OBJECTS $HASH_OBJ"
 LIBS="$LIBS $HASH_LINK"

-if [ $feat_ntp = "1" ] && [ $feat_nts = "1" ] && [ $try_gnutls = "1" ] && \
-    echo "$HASH_LINK" | grep 'nettle' > /dev/null; then
-  test_cflags="`pkg_config --cflags gnutls`"
-  test_link="`pkg_config --libs gnutls`"
-  if test_code 'gnutls' 'gnutls/gnutls.h' \
-    "$test_cflags" "$test_link" '
-      return gnutls_init(NULL, 0) +
-        gnutls_priority_init2(NULL, "", NULL, GNUTLS_PRIORITY_INIT_DEF_APPEND) +
-        gnutls_prf_rfc5705(NULL, 0, "", 0, "", 16, NULL);' &&
-    test_code 'AES128 in nettle' 'nettle/aes.h' '' "$LIBS" \
-      'aes128_set_encrypt_key(NULL, NULL);'
+if [ $feat_ntp = "1" ] && [ $feat_nts = "1" ] && [ $try_gnutls = "1" ]; then
+  if [ "$HASH_OBJ" = "hash_gnutls.o" ]; then
+    test_cflags=""
+    test_link=""
+  else
+    test_cflags="`pkg_config --cflags gnutls`"
+    test_link="`pkg_config --libs gnutls`"
+  fi
+  if test_code 'TLS1.3 in gnutls' 'gnutls/gnutls.h' \
+    "$test_cflags" "$test_link $LIBS" '
+      return gnutls_init((void *)1, 0) + GNUTLS_TLS1_3 +
+        gnutls_priority_init2((void *)1, "", NULL, GNUTLS_PRIORITY_INIT_DEF_APPEND) +
+        gnutls_prf_rfc5705((void *)1, 0, "", 0, "", 16, (void *)2);'
  then
-    EXTRA_OBJECTS="$EXTRA_OBJECTS nts_ke_client.o nts_ke_server.o nts_ke_session.o"
-    EXTRA_OBJECTS="$EXTRA_OBJECTS nts_ntp_auth.o nts_ntp_client.o nts_ntp_server.o"
-    EXTRA_OBJECTS="$EXTRA_OBJECTS siv_nettle.o"
-    LIBS="$LIBS $test_link"
-    MYCPPFLAGS="$MYCPPFLAGS $test_cflags"
-    add_def FEAT_NTS
-
-    add_def HAVE_SIV
-    if test_code 'SIV in nettle' \
+    if test_code 'AES-SIV-CMAC in nettle' \
      'nettle/siv-cmac.h' "" "$LIBS" \
-      'siv_cmac_aes128_set_key(NULL, NULL);'
+      'siv_cmac_aes128_set_key((void *)1, (void *)2);'
    then
+      EXTRA_OBJECTS="$EXTRA_OBJECTS siv_nettle.o"
+      add_def HAVE_SIV
      add_def HAVE_NETTLE_SIV_CMAC
+      if [ $try_aes_gcm_siv = "1" ] && test_code 'AES-GCM-SIV in nettle' \
+        'nettle/siv-gcm.h' "" "$LIBS" \
+        'siv_gcm_aes128_encrypt_message((void *)1, 0, NULL, 0, (void *)2, 16, (void *)3,
+                                        (void *)4);'
+      then
+        add_def HAVE_NETTLE_SIV_GCM
+      fi
+    else
+      if test_code 'AES-SIV-CMAC in gnutls' 'gnutls/crypto.h' \
+        "$test_cflags" "$test_link $LIBS" '
+          return gnutls_aead_cipher_init((void *)1, GNUTLS_CIPHER_AES_128_SIV, (void *)2);'
+      then
+        EXTRA_OBJECTS="$EXTRA_OBJECTS siv_gnutls.o"
+        add_def HAVE_SIV
+        if test_code 'gnutls_aead_cipher_set_key()' 'gnutls/crypto.h' \
+          "$test_cflags" "$test_link $LIBS" '
+            return gnutls_aead_cipher_set_key((void *)1, (void *)2);'
+        then
+          add_def HAVE_GNUTLS_AEAD_CIPHER_SET_KEY
+        fi
+      else
+        if test_code 'AES128 in nettle' 'nettle/aes.h' '' "$LIBS" \
+          'aes128_set_encrypt_key((void *)1, (void *)2);'
+        then
+          EXTRA_OBJECTS="$EXTRA_OBJECTS siv_nettle.o"
+          add_def HAVE_SIV
+        fi
+      fi
+    fi
+
+    if grep '#define HAVE_SIV' config.h > /dev/null; then
+      EXTRA_OBJECTS="$EXTRA_OBJECTS nts_ke_client.o nts_ke_server.o nts_ke_session.o"
+      EXTRA_OBJECTS="$EXTRA_OBJECTS nts_ntp_auth.o nts_ntp_client.o nts_ntp_server.o"
+      LIBS="$LIBS $test_link"
+      MYCPPFLAGS="$MYCPPFLAGS $test_cflags"
+      add_def FEAT_NTS
    fi
  fi
 fi
@@ -1086,6 +1129,7 @@ do
          s%@CFLAGS@%${MYCFLAGS}%;\
          s%@CPPFLAGS@%${MYCPPFLAGS}%;\
          s%@LDFLAGS@%${MYLDFLAGS}%;\
+          s%@GETDATE_CFLAGS@%${GETDATE_CFLAGS}%;\
          s%@LIBS@%${LIBS}%;\
          s%@EXTRA_LIBS@%${EXTRA_LIBS}%;\
          s%@EXTRA_CLI_LIBS@%${EXTRA_CLI_LIBS}%;\
--- a/contrib/bryan_christianson_1/README.txt
+++ b/contrib/bryan_christianson_1/README.txt
@@ -60,8 +60,8 @@ Support files
 Dates and sizes may differ
 -rw-r--r--  1 yourname  staff  2084  4 Aug 22:54 README.txt
 -rwxr-xr-x  1 yourname  staff   676  4 Aug 21:18 chronylogrotate.sh
-rw-r--r--  1 yourname  staff   543 18 Jul 20:10 org.tuxfamily.chronyc.plist
-rw-r--r--  1 yourname  staff   511 19 Jun 18:30 org.tuxfamily.chronyd.plist
+-rw-r--r--  1 yourname  staff   543 18 Jul 20:10 org.chrony-project.chronyc.plist
+-rw-r--r--  1 yourname  staff   511 19 Jun 18:30 org.chrony-project.chronyd.plist

 If you have used chrony support directories other than those suggested, you
 will need to edit each file and make the appropriate changes.
@@ -83,21 +83,21 @@ sudo chmod +x /usr/local/bin/chronylogrotate.sh
 sudo chown root:wheel /usr/local/bin/chronylogrotate.sh


-2. org.tuxfamily.chronyc.plist
+2. org.chrony-project.chronyc.plist
 This file is the launchd plist that runs logrotation each day. You may
 wish to edit this file to change the time of day at which the rotation
 will run, currently 04:05 am

-sudo cp org.tuxfamily.chronyc.plist /Library/LaunchDaemons
-sudo chown root:wheel /Library/LaunchDaemons/org.tuxfamily.chronyc.plist
-sudo chmod 0644 /Library/LaunchDaemons/org.tuxfamily.chronyc.plist
-sudo launchctl load -w /Library/LaunchDaemons/org.tuxfamily.chronyc.plist
+sudo cp org.chrony-project.chronyc.plist /Library/LaunchDaemons
+sudo chown root:wheel /Library/LaunchDaemons/org.chrony-project.chronyc.plist
+sudo chmod 0644 /Library/LaunchDaemons/org.chrony-project.chronyc.plist
+sudo launchctl load -w /Library/LaunchDaemons/org.chrony-project.chronyc.plist


-3. org.tuxfamily.chronyd.plist
+3. org.chrony-project.chronyd.plist
 This file is the launchd plist that runs chronyd when the Macintosh starts.

-sudo cp org.tuxfamily.chronyd.plist /Library/LaunchDaemons
-sudo chown root:wheel /Library/LaunchDaemons/org.tuxfamily.chronyd.plist
-sudo chmod 0644 /Library/LaunchDaemons/org.tuxfamily.chronyd.plist
-sudo launchctl load -w /Library/LaunchDaemons/org.tuxfamily.chronyd.plist
+sudo cp org.chrony-project.chronyd.plist /Library/LaunchDaemons
+sudo chown root:wheel /Library/LaunchDaemons/org.chrony-project.chronyd.plist
+sudo chmod 0644 /Library/LaunchDaemons/org.chrony-project.chronyd.plist
+sudo launchctl load -w /Library/LaunchDaemons/org.chrony-project.chronyd.plist
--- a/contrib/bryan_christianson_1/org.chrony-project.chronyc.plist
+++ b/contrib/bryan_christianson_1/org.chrony-project.chronyc.plist
@@ -3,7 +3,7 @@
 <plist version="1.0">
 <dict>
 	<key>Label</key>
-	<string>org.tuxfamily.logrotate</string>
+	<string>org.chrony-project.logrotate</string>
 	<key>KeepAlive</key>
 	<false/>
 	<key>ProgramArguments</key>
--- a/contrib/bryan_christianson_1/org.chrony-project.chronyd.plist
+++ b/contrib/bryan_christianson_1/org.chrony-project.chronyd.plist
@@ -3,7 +3,7 @@
 <plist version="1.0">
 <dict>
 	<key>Label</key>
-	<string>org.tuxfamily.chronyd</string>
+	<string>org.chrony-project.chronyd</string>
 	<key>Program</key>
 	<string>/usr/local/sbin/chronyd</string>
 	<key>ProgramArguments</key>
--- a/doc/chrony.conf.adoc
+++ b/doc/chrony.conf.adoc
--- a/doc/chronyc.adoc
+++ b/doc/chronyc.adoc
@@ -2,7 +2,7 @@
 //
 // Copyright (C) Richard P. Curnow  1997-2003
 // Copyright (C) Stephen Wadeley  2016
-// Copyright (C) Miroslav Lichvar  2009-2017
+// Copyright (C) Miroslav Lichvar  2009-2017, 2019-2023
 //
 // This program is free software; you can redistribute it and/or modify
 // it under the terms of version 2 of the GNU General Public License as
@@ -39,7 +39,7 @@ running.
 If no commands are specified on the command line, *chronyc* will expect input
 from the user. The prompt _chronyc>_ will be displayed when it is being run
 from a terminal. If *chronyc*'s input or output are redirected from or to a file,
-the prompt is not shown.
+the prompt will not be shown.

 There are two ways *chronyc* can access *chronyd*. One is the Internet
 Protocol (IPv4 or IPv6) and the other is a Unix domain socket, which is
@@ -51,7 +51,8 @@ running under a non-root user), it will try to connect to 127.0.0.1 and then

 Only the following monitoring commands, which do not affect the behaviour of
 *chronyd*, are allowed from the network: *activity*, *manual list*,
-*rtcdata*, *smoothing*, *sources*, *sourcestats*, *tracking*, *waitsync*. The
+*rtcdata*, *smoothing*, *sourcename*, *sources*, *sourcestats*, *tracking*,
+*waitsync*. The
 set of hosts from which *chronyd* will accept these commands can be configured
 with the <<chrony.conf.adoc#cmdallow,*cmdallow*>> directive in the *chronyd*'s
 configuration file or the <<cmdallow,*cmdallow*>> command in *chronyc*. By
@@ -59,9 +60,7 @@ default, the commands are accepted only from localhost (127.0.0.1 or ::1).

 All other commands are allowed only through the Unix domain socket. When sent
 over the network, *chronyd* will respond with a '`Not authorised`' error, even
-if it is from localhost. In chrony versions before 2.2 they were allowed
-from the network if they were authenticated with a password, but that is no
-longer supported.
+if it is from localhost.

 Having full access to *chronyd* via *chronyc* is more or less equivalent to
 being able to modify the *chronyd*'s configuration file and restart it.
@@ -79,11 +78,10 @@ This option disables resolving of IP addresses to hostnames, e.g. to avoid slow
 DNS lookups. Long addresses will not be truncated to fit into the column.

 *-N*::
-This option enables printing of the original names of NTP sources that were
-specified in the configuration file, or *chronyc* commands, and are internally
-used by *chronyd*. Without the *-n* and *-N* option, the names of NTP sources
-are obtained from reverse DNS lookups and can be different from the original
-names.
+This option enables printing of original hostnames or IP addresses of NTP
+sources that were specified in the configuration file, or *chronyc* commands.
+Without the *-n* and *-N* option, the printed hostnames are obtained from
+reverse DNS lookups and can be different from the specified hostnames.

 *-c*::
 This option enables printing of reports in a comma-separated values (CSV)
@@ -91,6 +89,10 @@ format. Reverse DNS lookups will be disabled, time will be printed as number of
 seconds since the epoch, and values in seconds will not be converted to other
 units.

+*-e*::
+With this option each *chronyc* response will end with a line containing a
+single dot.
+
 *-d*::
 This option enables printing of debugging messages if *chronyc* was compiled
 with debugging support.
@@ -101,12 +103,15 @@ With this option multiple commands can be specified. Each argument will be
 interpreted as a whole command.

 *-h* _host_::
-This option allows the user to specify which host (or comma-separated list of
-addresses) running the *chronyd* program is to be contacted. This allows for
-remote monitoring, without having to connect over SSH to the other host first.
+This option specifies the host to be contacted by *chronyc*. It can be
+specified with a hostname, IP address, or path to the local Unix domain socket.
+Multiple values can be specified as a comma-separated list to provide a
+fallback.
 +
-The default is to contact *chronyd* running on the same host where
-*chronyc* is being run.
+The default value is _@CHRONYRUNDIR@/chronyd.sock,127.0.0.1,::1_, i.e. the host
+where *chronyc* is being run. First, it tries to connect to the Unix domain
+socket and if that fails (e.g. due to running under a non-root user), it
+will try to connect to 127.0.0.1 and then ::1.

 *-p* _port_::
 This option allows the user to specify the UDP port number which the target
@@ -119,10 +124,14 @@ This option is ignored and is provided only for compatibility.
 *-a*::
 This option is ignored and is provided only for compatibility.

-*-v*::
+*-v*, *--version*::
 With this option *chronyc* displays its version number on the terminal and
 exits.

+*--help*::
+With this option *chronyc* displays a help message on the terminal and
+exits.
+
 == COMMANDS

 This section describes each of the commands available within the *chronyc*
@@ -175,17 +184,23 @@ stratum-2 and is synchronised from a stratum-1).
 This is the time (UTC) at which the last measurement from the reference
 source was processed.
 *System time*:::
-In normal operation, *chronyd* by default never steps the system clock, because
-any jump in the time can have adverse consequences for certain application
-programs. Instead, any error in the system clock is corrected by slightly
-speeding up or slowing down the system clock until the error has been removed,
-and then returning to the system clock's normal speed. A consequence of this is
-that there will be a period when the system clock (as read by other programs)
-will be different from *chronyd*'s estimate of the current true time (which it
-reports to NTP clients when it is operating in server mode). The value reported
-on this line is the difference due to this effect.
+This is the current offset between the NTP clock and system clock. The NTP
+clock is a software (virtual) clock maintained by *chronyd*, which is
+synchronised to the configured time sources and provides time to NTP clients.
+The system clock is synchronised to the NTP clock. To avoid steps in the
+system time, which might have adverse consequences for certain applications,
+the system clock is normally corrected only by speeding up or slowing down (up
+to the rate configured by the <<chrony.conf.adoc#maxslewrate,*maxslewrate*>>
+directive). If the offset is too large, this correction will take a very long
+time. A step can be forced by the <<makestep,*makestep*>> command, or the
+<<chrony.conf.adoc#makestep,*makestep*>> directive in the configuration file.
+
+Note that all other offsets reported by *chronyc* and most offsets in the log
+files are relative to the NTP clock, not the system clock.
 *Last offset*:::
-This is the estimated local offset on the last clock update.
+This is the estimated local offset on the last clock update. A positive value
+indicates the local time (as previously estimated true time) was ahead of the
+time sources.
 *RMS offset*:::
 This is a long-term average of the offset value.
 *Frequency*:::
@@ -316,18 +331,23 @@ The columns are as follows:
 This indicates the mode of the source. _^_ means a server, _=_ means a peer
 and _#_ indicates a locally connected reference clock.
 *S*:::
-This column indicates the state of the source.
-* _*_ indicates the source to which *chronyd* is currently synchronised.
-* _+_ indicates acceptable sources which are combined with the selected
-  source.
-* _-_ indicates acceptable sources which are excluded by the combining
-  algorithm.
-* _?_ indicates sources to which connectivity has been lost or whose packets
-  do not pass all tests. It is also shown at start-up, until at least 3 samples
-  have been gathered from it.
-* _x_ indicates a clock which *chronyd* thinks is a falseticker (i.e. its
-  time is inconsistent with a majority of other sources).
+This column indicates the selection state of the source.
+* _*_ indicates the best source which is currently selected for
+  synchronisation.
+* _+_ indicates other sources selected for synchronisation, which are combined
+  with the best source.
+* _-_ indicates a source which is considered to be selectable for
+  synchronisation, but not currently selected.
+* _x_ indicates a source which *chronyd* thinks is a falseticker (i.e. its
+  time is inconsistent with a majority of other sources, or sources specified
+  with the *trust* option).
 * _~_ indicates a source whose time appears to have too much variability.
+* _?_ indicates a source which is not considered to be selectable for
+  synchronisation for other reasons (e.g. unreachable, not synchronised, or
+  does not have enough measurements).
+{blank}:::
+The <<selectdata,*selectdata*>> command can be used to get more details about
+the selection state.
 *Name/IP address*:::
 This shows the name or the IP address of the source, or reference ID for reference
 clocks.
@@ -359,9 +379,9 @@ offset. This can be suffixed by _ns_ (indicating nanoseconds), _us_
 (indicating microseconds), _ms_ (indicating milliseconds), or _s_ (indicating
 seconds). The number to the left of the square brackets shows the original
 measurement, adjusted to allow for any slews applied to the local clock
-since. The number following the _+/-_ indicator shows the margin of error in
-the measurement. Positive offsets indicate that the local clock is ahead of
-the source.
+since. Positive offsets indicate that the local clock is ahead of the source.
+The number following the _+/-_ indicator shows the margin of error in the
+measurement (NTP root distance).

 [[sourcestats]]*sourcestats* [*-a*] [*-v*]::
 The *sourcestats* command displays information about the drift rate and offset
@@ -413,6 +433,116 @@ This is the estimated offset of the source.
 *Std Dev*:::
 This is the estimated sample standard deviation.

+[[selectdata]]*selectdata* [*-a*] [*-v*]::
+The *selectdata* command displays information specific to the selection of time
+sources. If the *-a* option is specified, all sources are displayed, including
+those that do not have a known address yet. With the *-v* option, extra caption
+lines are shown as a reminder of the meanings of the columns.
+
+An example of the output is shown below.
+
+----
+S Name/IP Address        Auth COpts EOpts Last Score     Interval  Leap
+=======================================================================
+D foo.example.net           Y ----- --TR-    4   1.0   -61ms   +62ms  N
+* bar.example.net           N ----- -----    0   1.0 -6846us +7305us  N
+ baz.example.net           N ----- -----   10   1.0 -7381us +7355us  N
+----
+
+The columns are as follows:
+
+*S*:::
+This column indicates the state of the source after the last source selection.
+It is similar to the state reported by the *sources* command, but more
+states are reported.
+{blank}:::
+The following states indicate the source is not considered selectable for
+synchronisation:
+* _N_ - has the *noselect* option.
+* _s_ - is not synchronised.
+* _M_ - does not have enough measurements.
+* _d_ - has a root distance larger than the maximum distance (configured by the
+        <<chrony.conf.adoc#maxdistance,*maxdistance*>> directive).
+* _~_ - has a jitter larger than the maximum jitter (configured by the
+        <<chrony.conf.adoc#maxjitter,*maxjitter*>> directive).
+* _w_ - waits for other sources to get out of the _M_ state.
+* _S_ - has older measurements than other sources.
+* _O_ - has a stratum equal or larger than the orphan stratum (configured by
+        the <<chrony.conf.adoc#local,*local*>> directive).
+* _T_ - does not fully agree with sources that have the *trust* option.
+* _x_ - does not agree with other sources (falseticker).
+{blank}:::
+The following states indicate the source is considered selectable, but it is
+not currently used for synchronisation:
+* _W_ - waits for other sources to be selectable (required by the
+        <<chrony.conf.adoc#minsources,*minsources*>> directive, or
+        the *require* option of another source).
+* _P_ - another selectable source is preferred due to the *prefer* option.
+* _U_ - waits for a new measurement (after selecting a different best source).
+* _D_ - has, or recently had, a root distance which is too large to be combined
+        with other sources (configured by the
+        <<chrony.conf.adoc#combinelimit,*combinelimit*>> directive).
+{blank}:::
+The following states indicate the source is used for synchronisation of the
+local clock:
+* _+_ - combined with the best source.
+* _*_ - selected as the best source to update the reference data (e.g. root
+        delay, root dispersion).
+*Name/IP address*:::
+This column shows the name or IP address of the source if it is an NTP server,
+or the reference ID if it is a reference clock.
+*Auth*:::
+This column indicites whether an authentication mechanism is enabled for the
+source. _Y_ means yes and _N_ means no.
+*COpts*:::
+This column displays the configured selection options of the source.
+* _N_ indicates the *noselect* option.
+* _P_ indicates the *prefer* option.
+* _T_ indicates the *trust* option.
+* _R_ indicates the *require* option.
+*EOpts*:::
+This column displays the current effective selection options of the source,
+which can be different from the configured options due to the authentication
+selection mode (configured by the
+<<chrony.conf.adoc#authselectmode,*authselectmode*>> directive). The symbols
+are the same as in the *COpts* column.
+*Last*:::
+This column displays how long ago was the last measurement of the source made
+when the selection was performed.
+*Score*:::
+This column displays the current score against the source in the _*_ state. The
+scoring system avoids frequent reselection when multiple sources have a similar
+root distance. A value larger than 1 indicates this source was better than the
+_*_ source in recent selections. If the score reaches 10, the best source will
+be reselected and the scores will be reset to 1.
+*Interval*:::
+This column displays the lower and upper endpoint of the interval which was
+expected to contain the true offset of the local clock considering the root
+distance at the time of the selection.
+*Leap*:::
+This column displays the current leap status of the source.
+* _N_ indicates the normal status (no leap second).
+* _+_ indicates that a leap second will be inserted at the end of the month.
+* _-_ indicates that a leap second will be deleted at the end of the month.
+* _?_ indicates the unknown status (i.e. no valid measurement was made).
+
+[[selectopts]]*selectopts* _address|refid_ [_+|-option_]...::
+The *selectopts* command modifies the configured selection options of an NTP
+source specified by IP address (or the _ID#XXXXXXXXXX_ identifier used for
+unknown addresses), or a reference clock specified by reference ID as a string.
+
+The selection options can be added with the *+* symbol or removed with the *-*
+symbol. The *selectdata* command can be used to verify the configuration. The
+modified options will be applied in the next source selection, e.g. when a new
+measurement is made, or the *reselect* command is executed.
+
+An example of using this command is shown below.
+
+----
+selectopts 1.2.3.4 -noselect +prefer
+selectopts GPS +trust
+----
+
 [[reselect]]*reselect*::
 To avoid excessive switching between sources, *chronyd* can stay synchronised
 to a source even when it is not currently the best one among the available
@@ -453,6 +583,78 @@ the offline state.
 the name of the server or peer was not resolved to an address yet; this source is
 not visible in the *sources* and *sourcestats* reports.

+[[authdata]]*authdata* [*-a*]::
+The *authdata* command displays information specific to authentication of NTP
+sources. If the *-a* option is specified, all sources are displayed, including
+those that do not have a known address yet. An example of the output is
+shown below.
+
+----
+Name/IP address             Mode KeyID Type KLen Last Atmp  NAK Cook CLen
+=========================================================================
+foo.example.net              NTS     1   15  256 135m    0    0    8  100
+bar.example.net               SK    30   13  128    -    0    0    0    0
+baz.example.net                -     0    0    0    -    0    0    0    0
+----
+
+The columns are as follows:
+
+*Name/IP address*:::
+This column shows the name or the IP address of the source.
+*Mode*:::
+This column shows which mechanism authenticates NTP packets received from the
+source. _NTS_ means Network Time Security, _SK_ means a symmetric key, and _-_
+means authentication is disabled.
+*KeyID*:::
+This column shows an identifier of the key used for authentication. With a
+symmetric key, it is the ID from the <<chrony.conf.adoc#keyfile,key file>>.
+With NTS, it is a number starting at zero and incremented by one with each
+successful key establishment using the NTS-KE protocol, i.e. it shows how many
+times the key establishment was performed with this source.
+*Type*:::
+This columns shows an identifier of the algorithm used for authentication.
+With a symmetric key, it is the hash function or cipher specified in the key
+file. With NTS, it is an authenticated encryption with associated data (AEAD)
+algorithm, which is negotiated in the NTS-KE protocol. The following values can
+be reported:
+* 1: MD5
+* 2: SHA1
+* 3: SHA256
+* 4: SHA384
+* 5: SHA512
+* 6: SHA3-224
+* 7: SHA3-256
+* 8: SHA3-384
+* 9: SHA3-512
+* 10: TIGER
+* 11: WHIRLPOOL
+* 13: AES128
+* 14: AES256
+* 15: AEAD-AES-SIV-CMAC-256
+* 30: AEAD-AES-128-GCM-SIV
+*KLen*:::
+This column shows the length of the key in bits.
+*Last*:::
+This column shows how long ago the last successful key establishment was
+performed. It is in seconds, or letters _m_, _h_, _d_ or _y_ indicate minutes,
+hours, days, or years.
+*Atmp*:::
+This column shows the number of attempts to perform the key establishment since
+the last successful key establishment. A number larger than 1 indicates a
+problem with the network or server.
+*NAK*:::
+This column shows whether an NTS NAK was received since the last request.
+A NAK indicates that authentication failed on the server side due to
+*chronyd* using a cookie which is no longer valid and that it needs to perform
+the key establishment again in order to get new cookies.
+*Cook*:::
+This column shows the number of NTS cookies that *chronyd* currently has. If
+the key establishment was successful, a number smaller than 8 indicates a
+problem with the network or server.
+*CLen*:::
+This column shows the length in bytes of the NTS cookie which will be used in
+the next request.
+
 [[ntpdata]]*ntpdata* [_address_]::
 The *ntpdata* command displays the last valid measurement and other
 NTP-specific information about the specified NTP source, or all NTP sources
@@ -486,6 +688,7 @@ RX timestamping : Kernel
 Total TX        : 24
 Total RX        : 24
 Total valid RX  : 24
+Total good RX   : 22
 ----
 +
 The fields are explained as follows:
@@ -523,7 +726,8 @@ packets sent to the source is more variable than the delay of packets sent
 from the source back.
 *NTP tests*:::
 Results of RFC 5905 tests 1 through 3, 5 through 7, and tests for maximum
-delay, delay ratio, delay dev ratio, and synchronisation loop.
+delay, delay ratio, delay dev ratio (or delay quantile), and synchronisation
+loop.
 *Interleaved*:::
 This shows if the response was in the interleaved mode.
 *Authenticated*:::
@@ -538,7 +742,10 @@ The number of packets sent to the source.
 *Total RX*:::
 The number of all packets received from the source.
 *Total valid RX*:::
-The number of valid packets received from the source.
+The number of packets which passed the first two groups of NTP tests.
+*Total good RX*:::
+The number of packets which passed all three groups of NTP tests, i.e. the NTP
+measurement was accepted.

 [[add_peer]]*add peer* _name_ [_option_]...::
 The *add peer* command allows a new NTP peer to be added whilst
@@ -625,7 +832,7 @@ alternative to the form with mask.
 _address_:::
 This is an IP address or a hostname. The burst command is applied only to
 that source.
-::
+{blank}::
 +
 If no _mask_ or _masked-address_ arguments are provided, every source will be
 matched.
@@ -763,12 +970,22 @@ current set of sources. It is equivalent to the *polltarget* option in the

 [[refresh]]*refresh*::
 The *refresh* command can be used to force *chronyd* to resolve the names of
-configured sources to IP addresses again, e.g. after suspending and resuming
-the machine in a different network.
+configured NTP sources to IP addresses again and replace any addresses missing
+in the list of resolved addresses.
 +
-Sources that stop responding will be replaced with newly resolved addresses
-automatically after 8 polling intervals, but this command can still be useful
-to replace them immediately and not wait until they are marked as unreachable.
+Sources that stop responding are replaced with newly resolved addresses
+automatically after 8 polling intervals. This command can be used to replace
+them immediately, e.g. after suspending and resuming the machine in a different
+network.
+
+Note that with pools which have more than 16 addresses, or not all IPv4 or IPv6
+addresses are included in a single DNS response (e.g. pool.ntp.org), this
+command might replace the addresses even if they are still in the pool.
+
+[[reload]]*reload* *sources*::
+The *reload sources* command causes *chronyd* to re-read all _*.sources_ files
+from the directories specified by the
+<<chrony.conf.adoc#sourcedir,*sourcedir*>> directive.

 [[sourcename]]*sourcename* _address_::
 The *sourcename* command prints the original hostname or address that was
@@ -815,7 +1032,7 @@ The columns are as as follows:
 . The regression residual at this point, in seconds. This allows '`outliers`'
  to be easily spotted, so that they can be deleted using the *manual delete*
  command.
-::
+{blank}::
 +
 The *delete* form of the command deletes a single sample. The parameter is the
 index of the sample, as shown in the first column of the output from *manual
@@ -886,10 +1103,17 @@ This command can be used to examine the effect of a series of *allow*, *allow
 all*, *deny*, and *deny all* commands specified either via *chronyc*, or in
 *chronyd*'s configuration file.

-[[clients]]*clients*::
+[[clients]]*clients* [*-p* _packets_] [*-k*] [*-r*]::
 This command shows a list of clients that have accessed the server, through
-either the NTP or command ports. It does not include accesses over
-the Unix domain command socket. There are no arguments.
+the NTP, command, or NTS-KE port. It does not include accesses over the Unix
+domain command socket.
+
+The *-p* option specifies the minimum number of received NTP or command
+packets, or accepted NTS-KE connections, needed to include a client in the
+list. The default value is 0, i.e. all clients are reported. With the *-k*
+option the last four columns will show the NTS-KE accesses instead of command
+accesses. If the *-r* option is specified, *chronyd* will reset the counters of
+received and dropped packets or connections after reporting the current values.
 +
 An example of the output is:
 +
@@ -914,20 +1138,18 @@ The columns are as follows:
 . The average interval between NTP packets.
 . The average interval between NTP packets after limiting the response rate.
 . Time since the last NTP packet was received
-. The number of command packets received from the client.
-. The number of command packets dropped to limit the response rate.
-. The average interval between command packets.
-. Time since the last command packet was received.
+. The number of command packets or NTS-KE connections received/accepted from
+  the client.
+. The number of command packets or NTS-KE connections dropped to limit the
+  response rate.
+. The average interval between command packets or NTS-KE connections.
+. Time since the last command packet or NTS-KE connection was
+  received/accepted.

 [[serverstats]]*serverstats*::
-The *serverstats* command displays how many valid NTP and command requests
-*chronyd* as a server received from clients, how many of them were dropped to
-limit the response rate as configured by the
-<<chrony.conf.adoc#ratelimit,*ratelimit*>> and
-<<chrony.conf.adoc#cmdratelimit,*cmdratelimit*>> directives, and how many
-client log records were dropped due to the memory limit configured by the
-<<chrony.conf.adoc#clientloglimit,*clientloglimit*>> directive. An example of
-the output is shown below.
+The *serverstats* command displays NTP and command server statistics.
+
+An example of the output is shown below.
 +
 ----
 NTP packets received       : 1598
@@ -935,7 +1157,70 @@ NTP packets dropped        : 8
 Command packets received   : 19
 Command packets dropped    : 0
 Client log records dropped : 0
+NTS-KE connections accepted: 3
+NTS-KE connections dropped : 0
+Authenticated NTP packets  : 189
+Interleaved NTP packets    : 43
+NTP timestamps held        : 44
+NTP timestamp span         : 120
+NTP daemon RX timestamps   : 0
+NTP daemon TX timestamps   : 1537
+NTP kernel RX timestamps   : 1590
+NTP kernel TX timestamps   : 43
+NTP hardware RX timestamps : 0
+NTP hardware TX timestamps : 0
 ----
+
+The fields have the following meaning:
+
+*NTP packets received*:::
+The number of valid NTP requests received by the server.
+*NTP packets dropped*:::
+The number of NTP requests dropped by the server due to rate limiting
+(configured by the <<chrony.conf.adoc#ratelimit,*ratelimit*>> directive).
+*Command packets received*:::
+The number of command requests received by the server.
+*Command packets dropped*:::
+The number of command requests dropped by the server due to rate limiting
+(configured by the <<chrony.conf.adoc#cmdratelimit,*cmdratelimit*>> directive).
+*Client log records dropped*:::
+The number of client log records dropped by the server to limit the memory use
+(configured by the <<chrony.conf.adoc#clientloglimit,*clientloglimit*>>
+directive).
+*NTS-KE connections accepted*:::
+The number of NTS-KE connections accepted by the server.
+*NTS-KE connections dropped*:::
+The number of NTS-KE connections dropped by the server due to rate limiting
+(configured by the <<chrony.conf.adoc#ntsratelimit,*ntsratelimit*>> directive).
+*Authenticated NTP packets*:::
+The number of received NTP requests that were authenticated (with a symmetric
+key or NTS).
+*Interleaved NTP packets*:::
+The number of received NTP requests that were detected to be in the interleaved
+mode.
+*NTP timestamps held*:::
+The number of pairs of receive and transmit timestamps that the server is
+currently holding in memory for clients using the interleaved mode.
+*NTP timestamp span*:::
+The interval (in seconds) covered by the currently held NTP timestamps.
+*NTP daemon RX timestamps*:::
+The number of NTP responses which included a receive timestamp captured by the
+daemon.
+*NTP daemon TX timestamps*:::
+The number of NTP responses which included a transmit timestamp captured by the
+daemon.
+*NTP kernel RX timestamps*:::
+The number of NTP responses which included a receive timestamp captured by the
+kernel.
+*NTP kernel TX timestamps*:::
+The number of NTP responses (in the interleaved mode) which included a transmit
+timestamp captured by the kernel.
+*NTP hardware RX timestamps*:::
+The number of NTP responses which included a receive timestamp captured by the
+NIC.
+*NTP hardware TX timestamps*:::
+The number of NTP responses (in the interleaved mode) which included a transmit
+timestamp captured by the NIC.

 [[allow]]*allow* [*all*] [_subnet_]::
 The effect of the allow command is identical to the
@@ -944,11 +1229,8 @@ The effect of the allow command is identical to the
 The syntax is illustrated in the following examples:
 +
 ----
-allow foo.example.net
-allow all 1.2
-allow 3.4.5
-allow 6.7.8/22
-allow 6.7.8.9/22
+allow 1.2.3.4
+allow all 3.4.5.0/24
 allow 2001:db8:789a::/48
 allow 0/0
 allow ::/0
@@ -963,11 +1245,8 @@ The effect of the allow command is identical to the
 The syntax is illustrated in the following examples:
 +
 ----
-deny foo.example.net
-deny all 1.2
-deny 3.4.5
-deny 6.7.8/22
-deny 6.7.8.9/22
+deny 1.2.3.4
+deny all 3.4.5.0/24
 deny 2001:db8:789a::/48
 deny 0/0
 deny ::/0
@@ -980,8 +1259,8 @@ deny all
 *local* *off*::
 The *local* command allows *chronyd* to be told that it is to appear as a
 reference source, even if it is not itself properly synchronised to an external
-source. (This can be used on isolated networks, to allow one computer to be a
-master time server with the other computers slaving to it.)
+source. This can be used on isolated networks, to allow a computer to be the
+primary time server for other computers.
 +
 The first form enables the local reference mode on the host. The syntax is
 identical to the <<chrony.conf.adoc#local,*local*>> directive in the
@@ -1120,7 +1399,7 @@ more than 1 second away from the system clock):
  error).
 . Save the RTC parameters to the RTC file (specified with the
  <<chrony.conf.adoc#rtcfile,*rtcfile*>> directive in the configuration file).
-::
+{blank}::
 +
 The last step is done as a precaution against the computer suffering a power
 failure before either the daemon exits or the <<writertc,*writertc*>> command
@@ -1153,30 +1432,34 @@ purged. An example of how to do this is shown below.
 ----
 # mv /var/log/chrony/measurements.log /var/log/chrony/measurements1.log
 # chronyc cyclelogs
-# ls -l /var/log/chrony
-rw-r--r--   1 root     root            0 Jun  8 18:17 measurements.log
-rw-r--r--   1 root     root        12345 Jun  8 18:17 measurements1.log
-# rm -f measurements1.log
+# rm /var/log/chrony/measurements1.log
 ----

 [[dump]]*dump*::
 The *dump* command causes *chronyd* to write its current history of
 measurements for each of its sources to dump files in the directory specified
 in the configuration file by the <<chrony.conf.adoc#dumpdir,*dumpdir*>>
+directive and also write server NTS keys and client NTS cookies to the
+directory specified by the <<chrony.conf.adoc#ntsdumpdir1,*ntsdumpdir*>>
 directive. Note that *chronyd* does this automatically when it exits. This
-command is mainly useful for inspection of the history whilst *chronyd* is
-running.
+command is mainly useful for inspection whilst *chronyd* is running.

 [[rekey]]*rekey*::
 The *rekey* command causes *chronyd* to re-read the key file specified in the
-configuration file by the <<chrony.conf.adoc#keyfile,*keyfile*>> directive.
+configuration file by the <<chrony.conf.adoc#keyfile,*keyfile*>> directive. It
+also re-reads the server NTS keys if
+<<chrony.conf.adoc#ntsdumpdir2,*ntsdumpdir*>> is specified and
+<<chrony.conf.adoc#ntsrotate,automatic rotation>> is disabled in the
+configuration file.

-[[reset]]*reset*::
-The *reset* command causes *chronyd* to drop all measurements and switch to the
-unsynchronised state. This command can help *chronyd* with recovery when the
-measurements are known to be no longer valid or accurate, e.g. due to moving
-the computer to a different network, or resuming the computer from a low-power
-state (which resets the system clock).
+[[reset]]*reset* *sources*::
+The *reset sources* command causes *chronyd* to drop all measurements and
+switch to the unsynchronised state. This command can help *chronyd* with
+recovery when the measurements are known to be no longer valid or accurate,
+e.g. due to moving the computer to a different network, or resuming the
+computer from a low-power state (which resets the system clock). *chronyd* will
+drop the measurements automatically when it detects the clock has made an
+unexpected jump, but the detection is not completely reliable.

 [[shutdown]]*shutdown*::
 The *shutdown* command causes *chronyd* to exit. This is equivalent to sending
@@ -1243,7 +1526,13 @@ keygen 73 SHA1 256
 +
 which generates a 256-bit SHA1 key with number 73. The printed line should
 then be securely transferred and added to the key files on both server and
-client, or peers.
+client, or peers. A different key should be generated for each client or peer.
+
+An example using the AES128 cipher is:
+
+----
+keygen 151 AES128
+----

 [[exit]]*exit*::
 [[quit]]*quit*::
@@ -1259,7 +1548,7 @@ The *help* command displays a summary of the commands and their arguments.
 == BUGS

 For instructions on how to report bugs, please visit
-https://chrony.tuxfamily.org/.
+https://chrony-project.org/.

 == AUTHORS

--- a/doc/chronyd.adoc
+++ b/doc/chronyd.adoc
@@ -55,7 +55,7 @@ IPv6 sockets will be created.

 *-f* _file_::
 This option can be used to specify an alternate location for the configuration
-file. The default value is _@SYSCONFDIR@/chrony.conf_.
+file. The compiled-in default value is _@SYSCONFDIR@/chrony.conf_.

 *-n*::
 When run in this mode, the program will not detach itself from the terminal.
@@ -76,14 +76,22 @@ the log file, syslog, or terminal. The following levels can be specified:
 0 (informational), 1 (warning), 2 (non-fatal error), and 3 (fatal error). The
 default value is 0.

+*-p*::
+When run in this mode, *chronyd* will print the configuration and exit. It will
+not detach from the terminal. This option can be used to verify the syntax of
+the configuration and get the whole configuration, even if it is split into
+multiple files and read by the *include* or *confdir* directive.
+
 *-q*::
 When run in this mode, *chronyd* will set the system clock once and exit. It
 will not detach from the terminal.

 *-Q*::
 This option is similar to the *-q* option, except it only prints the offset
-without making any corrections of the clock and it allows *chronyd* to be
-started without root privileges.
+without making any corrections of the clock and disables server ports to allow
+*chronyd* to be started without root privileges, assuming the configuration
+does not have any directives which would require them (e.g. *refclock*,
+*hwtimestamp*, *rtcfile*, etc).

 *-r*::
 This option will try to reload and then delete files containing sample
@@ -94,7 +102,7 @@ directive in the configuration file. This option is useful if you want to stop
 and restart *chronyd* briefly for any reason, e.g. to install a new version.
 However, it should be used only on systems where the kernel can maintain clock
 compensation whilst not under *chronyd*'s control (i.e. Linux, FreeBSD, NetBSD,
-Solaris, and macOS 10.13 or later).
+illumos, and macOS 10.13 or later).

 *-R*::
 When this option is used, the <<chrony.conf.adoc#initstepslew,*initstepslew*>>
@@ -131,51 +139,73 @@ running, but still allow it to adjust the frequency of the system clock.
 *-u* _user_::
 This option sets the name of the system user to which *chronyd* will switch
 after start in order to drop root privileges. It overrides the
-<<chrony.conf.adoc#user,*user*>> directive. The default value is
+<<chrony.conf.adoc#user,*user*>> directive. The compiled-in default value is
 _@DEFAULT_USER@_.
 +
 On Linux, *chronyd* needs to be compiled with support for the *libcap* library.
-On macOS, FreeBSD, NetBSD and Solaris *chronyd* forks into two processes.
+On macOS, FreeBSD, NetBSD, and illumos *chronyd* forks into two processes.
 The child process retains root privileges, but can only perform a very limited
 range of privileged system calls on behalf of the parent.

+*-U*::
+This option disables a check for root privileges to allow *chronyd* to be
+started under a non-root user, assuming the process will have all capabilities
+(e.g. provided by the service manager) and access to all files, directories,
+and devices, needed to operate correctly in the specified configuration. Note
+that different capabilities might be needed with different configurations and
+different Linux kernel versions. Starting *chronyd* under a non-root user is
+not recommended when the configuration is not known, or at least limited to
+specific directives.
+
 *-F* _level_::
-This option configures a system call filter when *chronyd* is compiled with
-support for the Linux secure computing (seccomp) facility. In level 1 the
-process is killed when a forbidden system call is made, in level -1 the SIGSYS
-signal is thrown instead and in level 0 the filter is disabled. The default
-value is 0.
+This option configures system call filters loaded by *chronyd* processes if it
+was compiled with support for the Linux secure computing (seccomp) facility.
+Three levels are defined: 0, 1, 2. The filters are disabled at level 0. At
+levels 1 and 2, *chronyd* will be killed if it makes a system call which is
+blocked by the filters. The level can be specified as a negative number to
+trigger the SIGSYS signal instead of SIGKILL, which can be useful for
+debugging. The default value is 0.
 +
-It's recommended to enable the filter only when it's known to work on the
-version of the system where *chrony* is installed as the filter needs to allow
-also system calls made from libraries that *chronyd* is using (e.g. libc) and
-different versions or implementations of the libraries may make different
-system calls. If the filter is missing some system call, *chronyd* could be
-killed even in normal operation.
+At level 1, the filters allow only selected system calls that are normally
+expected to be made by *chronyd*. Other system calls are blocked. This level is
+recommended only if it is known to work on the version of the system where
+*chrony* is installed. The filters need to allow also system calls made by
+libraries that *chronyd* is using (e.g. libc), but different versions or
+implementations of the libraries might make different system calls. If the
+filters are missing a system call, *chronyd* could be killed even in normal
+operation.
+
+At level 2, the filters block only a small number of specific system calls
+(e.g. fork and exec). This approach should avoid false positives, but the
+protection of the system against a compromised *chronyd* process is much more
+limited.
+
+The filters cannot be enabled with the *mailonchange* directive.

 *-P* _priority_::
-On Linux, this option will select the SCHED_FIFO real-time scheduler at the
-specified priority (which must be between 0 and 100). On macOS, this option
-must have either a value of 0 to disable the thread time
-constraint policy or 1 for the policy to be enabled. Other systems do not
+On Linux, FreeBSD, NetBSD, and illumos this option will select the SCHED_FIFO
+real-time scheduler at the specified priority (which must be between 0 and
+100). On macOS, this option must have either a value of 0 to disable the thread
+time constraint policy or 1 for the policy to be enabled. Other systems do not
 support this option. The default value is 0.

 *-m*::
 This option will lock *chronyd* into RAM so that it will never be paged out.
-This mode is only supported on Linux.
+This mode is only supported on Linux, FreeBSD, NetBSD, and illumos.

 *-x*::
 This option disables the control of the system clock. *chronyd* will not try to
 make any adjustments of the clock. It will assume the clock is free running and
 still track its offset and frequency relative to the estimated true time. This
-option allows *chronyd* to run without the capability to adjust or set the
-system clock (e.g. in some containers) in order to operate as an NTP server. It
-is not recommended to run *chronyd* (with or without *-x*) when another process
-is controlling the system clock.
+option allows *chronyd* to be started without the capability to adjust or set
+the system clock (e.g. in some containers) to operate as an NTP server.

-*-v*::
+*-v*, *--version*::
 With this option *chronyd* will print version number to the terminal and exit.

+*-h*, *--help*::
+With this option *chronyd* will print a help message to the terminal and exit.
+
 == FILES

 _@SYSCONFDIR@/chrony.conf_
@@ -187,7 +217,7 @@ _@SYSCONFDIR@/chrony.conf_
 == BUGS

 For instructions on how to report bugs, please visit
-https://chrony.tuxfamily.org/.
+https://chrony-project.org/.

 == AUTHORS

--- a/doc/faq.adoc
+++ b/doc/faq.adoc
--- a/doc/installation.adoc
+++ b/doc/installation.adoc
@@ -27,7 +27,7 @@ The following libraries with their development files, and programs, are needed
 to enable optional features:

 * pkg-config: detection of development libraries
-* Nettle, NSS, or LibTomCrypt: secure hash functions (`SECHASH`)
+* Nettle, GnuTLS, NSS, or LibTomCrypt: secure hash functions (`SECHASH`)
 * libcap: dropping root privileges on Linux (`DROPROOT`)
 * libseccomp: system call filter on Linux (`SCFILTER`)
 * GnuTLS and Nettle: Network Time Security (`NTS`)
@@ -94,13 +94,13 @@ want to enable the support, specify the `--disable-asyncdns` flag to

 If development files for the https://www.lysator.liu.se/~nisse/nettle/[Nettle],
 https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS[NSS], or
-http://www.libtom.net/LibTomCrypt/[libtomcrypt] library are available,
+https://www.libtom.net/LibTomCrypt/[libtomcrypt] library are available,
 `chronyd` will be built with support for other cryptographic hash functions
 than MD5, which can be used for NTP authentication with a symmetric key. If you
 don't want to enable the support, specify the `--disable-sechash` flag to
 `configure`.

-If development files for the editline or readline library are available,
+If development files for the editline library are available,
 `chronyc` will be built with line editing support. If you don't want this,
 specify the `--disable-readline` flag to `configure`.

@@ -170,43 +170,6 @@ https://github.com/seccomp/libseccomp[libseccomp] library and the
 the kernel attack surface and possibly prevent kernel exploits from `chronyd`
 if it is compromised.

-== Support for line editing libraries
-
-`chronyc` can be built with support for line editing, this allows you to use
-the cursor keys to replay and edit old commands. Two libraries are supported
-which provide such functionality, editline and GNU readline.
-
-Please note that readline since version 6.0 is licensed under GPLv3+ which is
-incompatible with chrony's license GPLv2. You should use editline instead if
-you don't want to use older readline versions.
-
-The `configure` script will automatically enable the line editing support if
-one of the supported libraries is available. If they are both available, the
-editline library will be used.
-
-If you don't want to use it (in which case `chronyc` will use a minimal command
-line interface), invoke `configure` like this:
-
----
-./configure --disable-readline other-options...
----
-
-If you have editline, readline or ncurses installed in locations that aren't
-normally searched by the compiler and linker, you need to use extra options:
-
-`--with-readline-includes=directory_name`::
-  This defines the name of the directory above the one where `readline.h` is.
-  `readline.h` is assumed to be in `editline` or `readline` subdirectory of the
-  named directory.
-
-`--with-readline-library=directory_name`::
-  This defines the directory containing the `libedit.a` or `libedit.so` file,
-  or `libreadline.a` or `libreadline.so` file.
-
-`--with-ncurses-library=directory_name`::
-  This defines the directory containing the `libncurses.a` or `libncurses.so`
-  file.
-
 == Extra options for package builders

 The `configure` and `make` procedures have some extra options that may be
--- a/examples/chrony-wait.service
+++ b/examples/chrony-wait.service
@@ -8,11 +8,39 @@ Wants=time-sync.target

 [Service]
 Type=oneshot
-# Wait up to ~10 minutes for chronyd to synchronize and the remaining
-# clock correction to be less than 0.1 seconds
-ExecStart=/usr/bin/chronyc -h 127.0.0.1,::1 waitsync 600 0.1 0.0 1
+# Wait for chronyd to update the clock and the remaining
+# correction to be less than 0.1 seconds
+ExecStart=/usr/bin/chronyc -h 127.0.0.1,::1 waitsync 0 0.1 0.0 1
+# Wait for at most 3 minutes
+TimeoutStartSec=180
 RemainAfterExit=yes
 StandardOutput=null

+CapabilityBoundingSet=
+DevicePolicy=closed
+DynamicUser=yes
+IPAddressAllow=localhost
+IPAddressDeny=any
+LockPersonality=yes
+MemoryDenyWriteExecute=yes
+PrivateDevices=yes
+PrivateUsers=yes
+ProtectClock=yes
+ProtectControlGroups=yes
+ProtectHome=yes
+ProtectHostname=yes
+ProtectKernelLogs=yes
+ProtectKernelModules=yes
+ProtectKernelTunables=yes
+ProtectProc=invisible
+ProtectSystem=strict
+RestrictAddressFamilies=AF_INET AF_INET6
+RestrictNamespaces=yes
+RestrictRealtime=yes
+SystemCallArchitectures=native
+SystemCallFilter=@system-service
+SystemCallFilter=~@privileged @resources
+UMask=0777
+
 [Install]
 WantedBy=multi-user.target
--- a/examples/chrony.conf.example2
+++ b/examples/chrony.conf.example2
@@ -1,5 +1,5 @@
 # Use public servers from the pool.ntp.org project.
-# Please consider joining the pool (http://www.pool.ntp.org/join.html).
+# Please consider joining the pool (https://www.pool.ntp.org/join.html).
 pool pool.ntp.org iburst

 # Record the rate at which the system clock gains/losses time.
@@ -25,9 +25,18 @@ rtcsync
 # Serve time even if not synchronized to a time source.
 #local stratum 10

+# Require authentication (nts or key option) for all NTP sources.
+#authselectmode require
+
 # Specify file containing keys for NTP authentication.
 #keyfile /etc/chrony.keys

+# Save NTS keys and cookies.
+ntsdumpdir /var/lib/chrony
+
+# Insert/delete leap seconds by slewing instead of stepping.
+#leapsecmode slew
+
 # Get TAI-UTC offset and leap seconds from the system tz database.
 #leapsectz right/UTC

--- a/examples/chrony.conf.example3
+++ b/examples/chrony.conf.example3
@@ -57,6 +57,20 @@

 ! maxdrift 100

+# By default, chronyd allows synchronisation to an unauthenticated NTP
+# source (i.e. specified without the nts and key options) if it agrees with
+# a majority of authenticated NTP sources, or if no authenticated source is
+# specified.  If you don't want chronyd to ever synchronise to an
+# unauthenticated NTP source, uncomment the first from the following lines.
+# If you don't want to synchronise to an unauthenticated NTP source only
+# when an authenticated source is specified, uncomment the second line.
+# If you want chronyd to ignore authentication in the source selection,
+# uncomment the third line.
+
+! authselectmode require
+! authselectmode prefer
+! authselectmode ignore
+
 #######################################################################
 ### FILENAMES ETC
 # Chrony likes to keep information about your computer's clock in files.
@@ -72,22 +86,37 @@ driftfile /var/lib/chrony/drift

 ! keyfile /etc/chrony.keys

+# If you specify an NTP server with the nts option to enable authentication
+# with the Network Time Security (NTS) mechanism, or enable server NTS with
+# the ntsservercert and ntsserverkey directives below, the following line will
+# allow the client/server to save the NTS keys and cookies in order to reduce
+# the number of key establishments (NTS-KE sessions).
+
+ntsdumpdir /var/lib/chrony
+
+# If chronyd is configured to act as an NTP server and you want to enable NTS
+# for its clients, you will need a TLS certificate and private key.  Uncomment
+# and edit the following lines to specify the locations of the certificate and
+# key.
+
+! ntsservercert /etc/.../foo.example.net.crt
+! ntsserverkey /etc/.../foo.example.net.key
+
 # chronyd can save the measurement history for the servers to files when
-# it it exits.  This is useful in 2 situations:
+# it exits.  This is useful in 2 situations:
 #
-# 1. On Linux, if you stop chronyd and restart it with '-r' (e.g. after
+# 1. If you stop chronyd and restart it with the '-r' option (e.g. after
 # an upgrade), the old measurements will still be relevant when chronyd
 # is restarted.  This will reduce the time needed to get accurate
-# gain/loss measurements, especially with a dial-up link.
+# gain/loss measurements.
 #
-# 2. Again on Linux, if you use the RTC support and start chronyd with
+# 2. On Linux, if you use the RTC support and start chronyd with
 # '-r -s' on bootup, measurements from the last boot will still be
 # useful (the real time clock is used to 'flywheel' chronyd between
 # boots).
 #
-# Enable these two options to use this.
+# Uncomment the following line to use this.

-! dumponexit
 ! dumpdir /var/lib/chrony

 # chronyd writes its process ID to a file.  If you try to start a second
@@ -116,6 +145,18 @@ driftfile /var/lib/chrony/drift

 ! makestep 1.0 3

+#######################################################################
+### LEAP SECONDS
+# A leap second is an occasional one-second correction of the UTC
+# time scale.  By default, chronyd tells the kernel to insert/delete
+# the leap second, which makes a backward/forward step to correct the
+# clock for it.  As with the makestep directive, this jump can upset
+# some applications.  If you prefer chronyd to make a gradual
+# correction, causing the clock to be off for a longer time, uncomment
+# the following line.
+
+! leapsecmode slew
+
 #######################################################################
 ### LOGGING
 # If you want to log information about the time measurements chronyd has
@@ -135,8 +176,6 @@ driftfile /var/lib/chrony/drift
 #######################################################################
 ### ACTING AS AN NTP SERVER
 # You might want the computer to be an NTP server for other computers.
-# e.g.  you might be running chronyd on a dial-up machine that has a LAN
-# sitting behind it with several 'satellite' computers on it.
 #
 # By default, chronyd does not allow any clients to access it.  You need
 # to explicitly enable access using 'allow' and 'deny' directives.
@@ -152,15 +191,6 @@ driftfile /var/lib/chrony/drift
 # You can have as many allow and deny directives as you need.  The order
 # is unimportant.

-# If you want chronyd to act as an NTP broadcast server, enable and edit
-# (and maybe copy) the following line.  This means that a broadcast
-# packet is sent to the address 192.168.1.255 every 60 seconds.  The
-# address MUST correspond to the broadcast address of one of the network
-# interfaces on your machine.  If you have multiple network interfaces,
-# add a broadcast line for each.
-
-! broadcast 60 192.168.1.255
-
 # If you want to present your computer's time for others to synchronise
 # with, even if you don't seem to be synchronised to any NTP servers
 # yourself, enable the following line.  The value 10 may be varied
--- a/examples/chrony.keys.example
+++ b/examples/chrony.keys.example
@@ -11,3 +11,5 @@
 #1 MD5 AVeryLongAndRandomPassword
 #2 MD5 HEX:12114855C7931009B4049EF3EFC48A139C3F989F
 #3 SHA1 HEX:B2159C05D6A219673A3B7E896B6DE07F6A440995
+#4 AES128 HEX:2DA837C4B6573748CA692B8C828E4891
+#5 AES256 HEX:2666B8099BFF2D5BA20876121788ED24D2BE59111B8FFB562F0F56AE6EC7246E
--- a/examples/chrony.nm-dispatcher
+++ b/examples/chrony.nm-dispatcher
@@ -1,15 +0,0 @@
-#!/bin/sh
-# This is a NetworkManager dispatcher / networkd-dispatcher script for
-# chronyd to set its NTP sources online or offline when a network interface
-# is configured or removed
-
-export LC_ALL=C
-
-# For NetworkManager consider only up/down events
-[ $# -ge 2 ] && [ "$2" != "up" ] && [ "$2" != "down" ] && exit 0
-
-# Note: for networkd-dispatcher routable.d ~= on and off.d ~= off
-
-chronyc onoffline > /dev/null 2>&1
-
-exit 0
--- a/examples/chrony.nm-dispatcher.dhcp
+++ b/examples/chrony.nm-dispatcher.dhcp
@@ -0,0 +1,49 @@
+#!/bin/sh
+# This is a NetworkManager dispatcher script for chronyd to update
+# its NTP sources with servers from DHCP options passed by NetworkManager
+# in the DHCP4_NTP_SERVERS and DHCP6_DHCP6_NTP_SERVERS environment variables.
+
+export LC_ALL=C
+
+interface=$1
+action=$2
+
+chronyc=/usr/bin/chronyc
+server_options=iburst
+server_dir=/var/run/chrony-dhcp
+
+dhcp_server_file=$server_dir/$interface.sources
+dhcp_ntp_servers="$DHCP4_NTP_SERVERS $DHCP6_DHCP6_NTP_SERVERS"
+
+add_servers_from_dhcp() {
+    rm -f "$dhcp_server_file"
+    for server in $dhcp_ntp_servers; do
+        # Check for invalid characters (from the DHCPv6 NTP FQDN suboption)
+        len1=$(printf '%s' "$server" | wc -c)
+        len2=$(printf '%s' "$server" | tr -d -c 'A-Za-z0-9:.-' | wc -c)
+        if [ "$len1" -ne "$len2" ] || [ "$len2" -lt 1 ] || [ "$len2" -gt 255 ]; then
+          continue
+        fi
+
+        printf 'server %s %s\n' "$server" "$server_options" >> "$dhcp_server_file"
+    done
+    $chronyc reload sources > /dev/null 2>&1 || :
+}
+
+clear_servers_from_dhcp() {
+    if [ -f "$dhcp_server_file" ]; then
+        rm -f "$dhcp_server_file"
+        $chronyc reload sources > /dev/null 2>&1 || :
+    fi
+}
+
+mkdir -p $server_dir
+
+case "$action" in
+    up|dhcp4-change|dhcp6-change)
+        add_servers_from_dhcp;;
+    down)
+        clear_servers_from_dhcp;;
+esac
+
+exit 0
--- a/examples/chrony.nm-dispatcher.onoffline
+++ b/examples/chrony.nm-dispatcher.onoffline
@@ -0,0 +1,29 @@
+#!/bin/sh
+# This is a NetworkManager dispatcher / networkd-dispatcher script for
+# chronyd to set its NTP sources online or offline when a network interface
+# is configured or removed
+
+export LC_ALL=C
+
+chronyc=/usr/bin/chronyc
+
+# For NetworkManager consider only selected events
+if [ $# -ge 2 ]; then
+    case "$2" in
+        up|down|connectivity-change)
+            ;;
+        dhcp4-change|dhcp6-change)
+            # Actions "up" and "connectivity-change" in some cases do not
+            # guarantee that the interface has a route (e.g. a bond).
+            # dhcp(x)-change handles at least cases that use DHCP.
+            ;;
+        *)
+            exit 0;;
+    esac
+fi
+
+# Note: for networkd-dispatcher routable.d ~= on and off.d ~= off
+
+$chronyc onoffline > /dev/null 2>&1
+
+exit 0
--- a/examples/chronyd-restricted.service
+++ b/examples/chronyd-restricted.service
@@ -0,0 +1,58 @@
+# This is a more restricted version of the chronyd service intended for
+# minimal NTP/NTS client configurations. The daemon is started without root
+# privileges and is allowed to write only to its own runtime, state, and log
+# directories. It cannot bind to privileged ports in order to operate as an
+# NTP server, or provide monitoring access over IPv4/IPv6. It cannot use
+# reference clocks, HW timestamping, RTC tracking, and other features.
+[Unit]
+Description=NTP client (restricted)
+Documentation=man:chronyd(8) man:chrony.conf(5)
+After=chronyd.service ntpdate.service sntp.service ntpd.service
+Conflicts=chronyd.service ntpd.service systemd-timesyncd.service
+ConditionCapability=CAP_SYS_TIME
+
+[Service]
+Type=forking
+PIDFile=/run/chrony/chronyd.pid
+EnvironmentFile=-/etc/sysconfig/chronyd
+ExecStart=/usr/sbin/chronyd -U $OPTIONS
+
+User=chrony
+LogsDirectory=chrony
+LogsDirectoryMode=0750
+RuntimeDirectory=chrony
+RuntimeDirectoryMode=0750
+RuntimeDirectoryPreserve=restart
+StateDirectory=chrony
+StateDirectoryMode=0750
+
+AmbientCapabilities=CAP_SYS_TIME
+CapabilityBoundingSet=CAP_SYS_TIME
+DevicePolicy=closed
+LockPersonality=yes
+MemoryDenyWriteExecute=yes
+NoNewPrivileges=yes
+PrivateDevices=yes
+PrivateTmp=yes
+# This breaks adjtimex()
+#PrivateUsers=yes
+ProtectControlGroups=yes
+ProtectHome=yes
+ProtectHostname=yes
+ProtectKernelLogs=yes
+ProtectKernelModules=yes
+ProtectKernelTunables=yes
+ProtectProc=invisible
+ProtectSystem=strict
+RemoveIPC=yes
+RestrictAddressFamilies=AF_INET AF_INET6 AF_UNIX
+RestrictNamespaces=yes
+RestrictRealtime=yes
+RestrictSUIDSGID=yes
+SystemCallArchitectures=native
+SystemCallFilter=~@cpu-emulation @debug @module @mount @obsolete @raw-io
+SystemCallFilter=~@reboot @resources @swap
+UMask=0077
+
+[Install]
+WantedBy=multi-user.target
--- a/examples/chronyd.service
+++ b/examples/chronyd.service
@@ -10,9 +10,39 @@ Type=forking
 PIDFile=/run/chrony/chronyd.pid
 EnvironmentFile=-/etc/sysconfig/chronyd
 ExecStart=/usr/sbin/chronyd $OPTIONS
+
+CapabilityBoundingSet=~CAP_AUDIT_CONTROL CAP_AUDIT_READ CAP_AUDIT_WRITE
+CapabilityBoundingSet=~CAP_BLOCK_SUSPEND CAP_KILL CAP_LEASE CAP_LINUX_IMMUTABLE
+CapabilityBoundingSet=~CAP_MAC_ADMIN CAP_MAC_OVERRIDE CAP_MKNOD CAP_SYS_ADMIN
+CapabilityBoundingSet=~CAP_SYS_BOOT CAP_SYS_CHROOT CAP_SYS_MODULE CAP_SYS_PACCT
+CapabilityBoundingSet=~CAP_SYS_PTRACE CAP_SYS_RAWIO CAP_SYS_TTY_CONFIG CAP_WAKE_ALARM
+DeviceAllow=char-pps rw
+DeviceAllow=char-ptp rw
+DeviceAllow=char-rtc rw
+DevicePolicy=closed
+LockPersonality=yes
+MemoryDenyWriteExecute=yes
+NoNewPrivileges=yes
 PrivateTmp=yes
+ProtectControlGroups=yes
 ProtectHome=yes
-ProtectSystem=full
+ProtectHostname=yes
+ProtectKernelLogs=yes
+ProtectKernelModules=yes
+ProtectKernelTunables=yes
+ProtectProc=invisible
+ProtectSystem=strict
+ReadWritePaths=/run /var/lib/chrony -/var/log
+RestrictAddressFamilies=AF_INET AF_INET6 AF_UNIX
+RestrictNamespaces=yes
+RestrictSUIDSGID=yes
+SystemCallArchitectures=native
+SystemCallFilter=~@cpu-emulation @debug @module @mount @obsolete @raw-io @reboot @swap
+
+# Adjust restrictions for /usr/sbin/sendmail (mailonchange directive)
+NoNewPrivileges=no
+ReadWritePaths=-/var/spool
+RestrictAddressFamilies=AF_NETLINK

 [Install]
 WantedBy=multi-user.target
--- a/getdate.y
+++ b/getdate.y
@@ -448,9 +448,9 @@ o_merid	: /* NULL */
   the same signature as the function definition does. */
 #include "getdate.h"

-extern struct tm	*gmtime ();
-extern struct tm	*localtime ();
-extern time_t		mktime ();
+extern struct tm	*gmtime (const time_t *timep);
+extern struct tm	*localtime (const time_t *timep);
+extern time_t		mktime (struct tm *tm);

 /* Month and day table. */
 static TABLE const MonthDayTable[] = {
@@ -641,16 +641,13 @@ static TABLE const MilitaryTable[] = {

 /* ARGSUSED */
 static int
-yyerror (s)
-     char *s ATTRIBUTE_UNUSED;
+yyerror (char *s ATTRIBUTE_UNUSED)
 {
  return 0;
 }

 static int
-ToHour (Hours, Meridian)
-     int Hours;
-     MERIDIAN Meridian;
+ToHour (int Hours, MERIDIAN Meridian)
 {
  switch (Meridian)
    {
@@ -677,8 +674,7 @@ ToHour (Hours, Meridian)
 }

 static int
-ToYear (Year)
-     int Year;
+ToYear (int Year)
 {
  if (Year < 0)
    Year = -Year;
@@ -694,8 +690,7 @@ ToYear (Year)
 }

 static int
-LookupWord (buff)
-     char *buff;
+LookupWord (char *buff)
 {
  register char *p;
  register char *q;
--- a/hash.h
+++ b/hash.h
@@ -31,12 +31,26 @@
 /* length of hash values produced by SHA512 */
 #define MAX_HASH_LENGTH 64

-extern int HSH_GetHashId(const char *name);
+typedef enum {
+  HSH_INVALID = 0,
+  HSH_MD5 = 1,
+  HSH_SHA1 = 2,
+  HSH_SHA256 = 3,
+  HSH_SHA384 = 4,
+  HSH_SHA512 = 5,
+  HSH_SHA3_224 = 6,
+  HSH_SHA3_256 = 7,
+  HSH_SHA3_384 = 8,
+  HSH_SHA3_512 = 9,
+  HSH_TIGER = 10,
+  HSH_WHIRLPOOL = 11,
+  HSH_MD5_NONCRYPTO = 10000, /* For NTPv4 reference ID */
+} HSH_Algorithm;

-extern unsigned int HSH_Hash(int id,
-    const unsigned char *in1, unsigned int in1_len,
-    const unsigned char *in2, unsigned int in2_len,
-    unsigned char *out, unsigned int out_len);
+extern int HSH_GetHashId(HSH_Algorithm algorithm);
+
+extern int HSH_Hash(int id, const void *in1, int in1_len, const void *in2, int in2_len,
+                    unsigned char *out, int out_len);

 extern void HSH_Finalise(void);

--- a/hash_gnutls.c
+++ b/hash_gnutls.c
@@ -0,0 +1,145 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2021
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  Crypto hashing using the GnuTLS library
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <gnutls/crypto.h>
+
+#include "hash.h"
+#include "logging.h"
+
+struct hash {
+  const HSH_Algorithm algorithm;
+  const gnutls_digest_algorithm_t type;
+  gnutls_hash_hd_t handle;
+};
+
+static struct hash hashes[] = {
+  { HSH_MD5_NONCRYPTO, GNUTLS_DIG_MD5, NULL },
+  { HSH_MD5, GNUTLS_DIG_MD5, NULL },
+  { HSH_SHA1, GNUTLS_DIG_SHA1, NULL },
+  { HSH_SHA256, GNUTLS_DIG_SHA256, NULL },
+  { HSH_SHA384, GNUTLS_DIG_SHA384, NULL },
+  { HSH_SHA512, GNUTLS_DIG_SHA512, NULL },
+  { HSH_SHA3_224, GNUTLS_DIG_SHA3_224, NULL },
+  { HSH_SHA3_256, GNUTLS_DIG_SHA3_256, NULL },
+  { HSH_SHA3_384, GNUTLS_DIG_SHA3_384, NULL },
+  { HSH_SHA3_512, GNUTLS_DIG_SHA3_512, NULL },
+  { 0, 0, NULL }
+};
+
+static int gnutls_initialised = 0;
+
+int
+HSH_GetHashId(HSH_Algorithm algorithm)
+{
+  int id, r;
+
+  if (!gnutls_initialised) {
+    r = gnutls_global_init();
+    if (r < 0)
+      LOG_FATAL("Could not initialise %s : %s", "gnutls", gnutls_strerror(r));
+    gnutls_initialised = 1;
+  }
+
+  for (id = 0; hashes[id].algorithm != 0; id++) {
+    if (hashes[id].algorithm == algorithm)
+      break;
+  }
+
+  if (hashes[id].algorithm == 0)
+    return -1;
+
+  if (hashes[id].handle)
+    return id;
+
+  if (algorithm == HSH_MD5_NONCRYPTO)
+    GNUTLS_FIPS140_SET_LAX_MODE();
+
+  r = gnutls_hash_init(&hashes[id].handle, hashes[id].type);
+
+  if (algorithm == HSH_MD5_NONCRYPTO)
+    GNUTLS_FIPS140_SET_STRICT_MODE();
+
+  if (r < 0) {
+    DEBUG_LOG("Could not initialise %s : %s", "hash", gnutls_strerror(r));
+    hashes[id].handle = NULL;
+    return -1;
+  }
+
+  return id;
+}
+
+int
+HSH_Hash(int id, const void *in1, int in1_len, const void *in2, int in2_len,
+         unsigned char *out, int out_len)
+{
+  unsigned char buf[MAX_HASH_LENGTH];
+  gnutls_hash_hd_t handle;
+  int hash_len;
+
+  if (in1_len < 0 || in2_len < 0 || out_len < 0)
+    return 0;
+
+  handle = hashes[id].handle;
+  hash_len = gnutls_hash_get_len(hashes[id].type);
+
+  if (out_len > hash_len)
+    out_len = hash_len;
+
+  if (hash_len > sizeof (buf))
+    return 0;
+
+  if (gnutls_hash(handle, in1, in1_len) < 0 ||
+      (in2 && gnutls_hash(handle, in2, in2_len) < 0)) {
+    /* Reset the state */
+    gnutls_hash_output(handle, buf);
+    return 0;
+  }
+
+  gnutls_hash_output(handle, buf);
+  memcpy(out, buf, out_len);
+
+  return out_len;
+}
+
+void
+HSH_Finalise(void)
+{
+  int i;
+
+  if (!gnutls_initialised)
+    return;
+
+  for (i = 0; hashes[i].algorithm != 0; i++) {
+    if (hashes[i].handle)
+      gnutls_hash_deinit(hashes[i].handle, NULL);
+  }
+
+  gnutls_global_deinit();
+}
--- a/hash_intmd5.c
+++ b/hash_intmd5.c
@@ -36,20 +36,22 @@
 static MD5_CTX ctx;

 int
-HSH_GetHashId(const char *name)
+HSH_GetHashId(HSH_Algorithm algorithm)
 {
  /* only MD5 is supported */
-  if (strcmp(name, "MD5"))
+  if (algorithm != HSH_MD5 && algorithm != HSH_MD5_NONCRYPTO)
    return -1;

  return 0;
 }

-unsigned int
-HSH_Hash(int id, const unsigned char *in1, unsigned int in1_len,
-    const unsigned char *in2, unsigned int in2_len,
-    unsigned char *out, unsigned int out_len)
+int
+HSH_Hash(int id, const void *in1, int in1_len, const void *in2, int in2_len,
+         unsigned char *out, int out_len)
 {
+  if (in1_len < 0 || in2_len < 0 || out_len < 0)
+    return 0;
+
  MD5Init(&ctx);
  MD5Update(&ctx, in1, in1_len);
  if (in2)
--- a/hash_nettle.c
+++ b/hash_nettle.c
@@ -35,36 +35,39 @@
 #include "memory.h"

 struct hash {
-  const char *name;
+  const HSH_Algorithm algorithm;
  const char *int_name;
  const struct nettle_hash *nettle_hash;
  void *context;
 };

 static struct hash hashes[] = {
-  { "MD5", "md5", NULL, NULL },
-  { "SHA1", "sha1", NULL, NULL },
-  { "SHA256", "sha256", NULL, NULL },
-  { "SHA384", "sha384", NULL, NULL },
-  { "SHA512", "sha512", NULL, NULL },
-  { "SHA3-224", "sha3_224", NULL, NULL },
-  { "SHA3-256", "sha3_256", NULL, NULL },
-  { "SHA3-384", "sha3_384", NULL, NULL },
-  { "SHA3-512", "sha3_512", NULL, NULL },
-  { NULL, NULL, NULL, NULL }
+  { HSH_MD5, "md5", NULL, NULL },
+  { HSH_SHA1, "sha1", NULL, NULL },
+  { HSH_SHA256, "sha256", NULL, NULL },
+  { HSH_SHA384, "sha384", NULL, NULL },
+  { HSH_SHA512, "sha512", NULL, NULL },
+  { HSH_SHA3_224, "sha3_224", NULL, NULL },
+  { HSH_SHA3_256, "sha3_256", NULL, NULL },
+  { HSH_SHA3_384, "sha3_384", NULL, NULL },
+  { HSH_SHA3_512, "sha3_512", NULL, NULL },
+  { 0, NULL, NULL, NULL }
 };

 int
-HSH_GetHashId(const char *name)
+HSH_GetHashId(HSH_Algorithm algorithm)
 {
  int id, nid;

-  for (id = 0; hashes[id].name; id++) {
-    if (!strcmp(name, hashes[id].name))
+  if (algorithm == HSH_MD5_NONCRYPTO)
+    algorithm = HSH_MD5;
+
+  for (id = 0; hashes[id].algorithm != 0; id++) {
+    if (hashes[id].algorithm == algorithm)
      break;
  }

-  if (!hashes[id].name)
+  if (hashes[id].algorithm == 0)
    return -1;

  if (hashes[id].context)
@@ -84,14 +87,16 @@ HSH_GetHashId(const char *name)
  return id;
 }

-unsigned int
-HSH_Hash(int id, const unsigned char *in1, unsigned int in1_len,
-         const unsigned char *in2, unsigned int in2_len,
-         unsigned char *out, unsigned int out_len)
+int
+HSH_Hash(int id, const void *in1, int in1_len, const void *in2, int in2_len,
+         unsigned char *out, int out_len)
 {
  const struct nettle_hash *hash;
  void *context;

+  if (in1_len < 0 || in2_len < 0 || out_len < 0)
+    return 0;
+
  hash = hashes[id].nettle_hash;
  context = hashes[id].context;

@@ -112,7 +117,7 @@ HSH_Finalise(void)
 {
  int i;

-  for (i = 0; hashes[i].name; i++) {
+  for (i = 0; hashes[i].algorithm != 0; i++) {
    if (hashes[i].context)
      Free(hashes[i].context);
  }
--- a/hash_nss.c
+++ b/hash_nss.c
@@ -38,30 +38,33 @@ static NSSLOWInitContext *ictx;

 struct hash {
  HASH_HashType type;
-  const char *name;
+  HSH_Algorithm algorithm;
  NSSLOWHASHContext *context;
 };

 static struct hash hashes[] = {
-  { HASH_AlgMD5, "MD5", NULL },
-  { HASH_AlgSHA1, "SHA1", NULL },
-  { HASH_AlgSHA256, "SHA256", NULL },
-  { HASH_AlgSHA384, "SHA384", NULL },
-  { HASH_AlgSHA512, "SHA512", NULL },
-  { 0, NULL, NULL }
+  { HASH_AlgMD5, HSH_MD5, NULL },
+  { HASH_AlgSHA1, HSH_SHA1, NULL },
+  { HASH_AlgSHA256, HSH_SHA256, NULL },
+  { HASH_AlgSHA384, HSH_SHA384, NULL },
+  { HASH_AlgSHA512, HSH_SHA512, NULL },
+  { 0, 0, NULL }
 };

 int
-HSH_GetHashId(const char *name)
+HSH_GetHashId(HSH_Algorithm algorithm)
 {
  int i;

-  for (i = 0; hashes[i].name; i++) {
-    if (!strcmp(name, hashes[i].name))
+  if (algorithm == HSH_MD5_NONCRYPTO)
+    algorithm = HSH_MD5;
+
+  for (i = 0; hashes[i].algorithm != 0; i++) {
+    if (hashes[i].algorithm == algorithm)
      break;
  }

-  if (!hashes[i].name)
+  if (hashes[i].algorithm == 0)
    return -1; /* not found */

  if (!ictx && !(ictx = NSSLOW_Init()))
@@ -74,14 +77,16 @@ HSH_GetHashId(const char *name)
  return i;
 }

-unsigned int
-HSH_Hash(int id, const unsigned char *in1, unsigned int in1_len,
-    const unsigned char *in2, unsigned int in2_len,
-    unsigned char *out, unsigned int out_len)
+int
+HSH_Hash(int id, const void *in1, int in1_len, const void *in2, int in2_len,
+         unsigned char *out, int out_len)
 {
  unsigned char buf[MAX_HASH_LENGTH];
  unsigned int ret = 0;

+  if (in1_len < 0 || in2_len < 0 || out_len < 0)
+    return 0;
+
  NSSLOWHASH_Begin(hashes[id].context);
  NSSLOWHASH_Update(hashes[id].context, in1, in1_len);
  if (in2)
@@ -99,7 +104,7 @@ HSH_Finalise(void)
 {
  int i;

-  for (i = 0; hashes[i].name; i++) {
+  for (i = 0; hashes[i].algorithm != 0; i++) {
    if (hashes[i].context)
      NSSLOWHASH_Destroy(hashes[i].context);
  }
--- a/hash_tomcrypt.c
+++ b/hash_tomcrypt.c
@@ -32,51 +32,54 @@
 #include "util.h"

 struct hash {
-  const char *name;
+  HSH_Algorithm algorithm;
  const char *int_name;
  const struct ltc_hash_descriptor *desc;
 };

 static const struct hash hashes[] = {
-  { "MD5", "md5", &md5_desc },
+  { HSH_MD5, "md5", &md5_desc },
 #ifdef LTC_SHA1
-  { "SHA1", "sha1", &sha1_desc },
+  { HSH_SHA1, "sha1", &sha1_desc },
 #endif
 #ifdef LTC_SHA256
-  { "SHA256", "sha256", &sha256_desc },
+  { HSH_SHA256, "sha256", &sha256_desc },
 #endif
 #ifdef LTC_SHA384
-  { "SHA384", "sha384", &sha384_desc },
+  { HSH_SHA384, "sha384", &sha384_desc },
 #endif
 #ifdef LTC_SHA512
-  { "SHA512", "sha512", &sha512_desc },
+  { HSH_SHA512, "sha512", &sha512_desc },
 #endif
 #ifdef LTC_SHA3
-  { "SHA3-224", "sha3-224", &sha3_224_desc },
-  { "SHA3-256", "sha3-256", &sha3_256_desc },
-  { "SHA3-384", "sha3-384", &sha3_384_desc },
-  { "SHA3-512", "sha3-512", &sha3_512_desc },
+  { HSH_SHA3_224, "sha3-224", &sha3_224_desc },
+  { HSH_SHA3_256, "sha3-256", &sha3_256_desc },
+  { HSH_SHA3_384, "sha3-384", &sha3_384_desc },
+  { HSH_SHA3_512, "sha3-512", &sha3_512_desc },
 #endif
 #ifdef LTC_TIGER
-  { "TIGER", "tiger", &tiger_desc },
+  { HSH_TIGER, "tiger", &tiger_desc },
 #endif
 #ifdef LTC_WHIRLPOOL
-  { "WHIRLPOOL", "whirlpool", &whirlpool_desc },
+  { HSH_WHIRLPOOL, "whirlpool", &whirlpool_desc },
 #endif
-  { NULL, NULL, NULL }
+  { 0, NULL, NULL }
 };

 int
-HSH_GetHashId(const char *name)
+HSH_GetHashId(HSH_Algorithm algorithm)
 {
  int i, h;

-  for (i = 0; hashes[i].name; i++) {
-    if (!strcmp(name, hashes[i].name))
+  if (algorithm == HSH_MD5_NONCRYPTO)
+    algorithm = HSH_MD5;
+
+  for (i = 0; hashes[i].algorithm != 0; i++) {
+    if (hashes[i].algorithm == algorithm)
      break;
  }

-  if (!hashes[i].name)
+  if (hashes[i].algorithm == 0)
    return -1; /* not found */

  h = find_hash(hashes[i].int_name);
@@ -89,15 +92,17 @@ HSH_GetHashId(const char *name)
  return find_hash(hashes[i].int_name);
 }

-unsigned int
-HSH_Hash(int id, const unsigned char *in1, unsigned int in1_len,
-    const unsigned char *in2, unsigned int in2_len,
-    unsigned char *out, unsigned int out_len)
+int
+HSH_Hash(int id, const void *in1, int in1_len, const void *in2, int in2_len,
+         unsigned char *out, int out_len)
 {
  unsigned char buf[MAX_HASH_LENGTH];
  unsigned long len;
  int r;

+  if (in1_len < 0 || in2_len < 0 || out_len < 0)
+    return 0;
+
  len = sizeof (buf);
  if (in2)
    r = hash_memory_multi(id, buf, &len,
--- a/hwclock.c
+++ b/hwclock.c
@@ -2,7 +2,7 @@
  chronyd/chronyc - Programs for keeping computer clocks accurate.

 **********************************************************************
- * Copyright (C) Miroslav Lichvar  2016-2018
+ * Copyright (C) Miroslav Lichvar  2016-2018, 2022
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
@@ -33,6 +33,7 @@
 #include "local.h"
 #include "logging.h"
 #include "memory.h"
+#include "quantiles.h"
 #include "regress.h"
 #include "util.h"

@@ -43,6 +44,13 @@
 /* Maximum acceptable frequency offset of the clock */
 #define MAX_FREQ_OFFSET (2.0 / 3.0)

+/* Quantiles for filtering readings by delay */
+#define DELAY_QUANT_MIN_K 1
+#define DELAY_QUANT_MAX_K 2
+#define DELAY_QUANT_Q 10
+#define DELAY_QUANT_REPEAT 7
+#define DELAY_QUANT_MIN_STEP 1.0e-9
+
 struct HCL_Instance_Record {
  /* HW and local reference timestamp */
  struct timespec hw_ref;
@@ -64,12 +72,18 @@ struct HCL_Instance_Record {
  /* Minimum interval between samples */
  double min_separation;

+  /* Expected precision of readings */
+  double precision;
+
  /* Flag indicating the offset and frequency values are valid */
  int valid_coefs;

  /* Estimated offset and frequency of HW clock relative to local clock */
  double offset;
  double frequency;
+
+  /* Estimated quantiles of reading delay */
+  QNT_Instance delay_quants;
 };

 /* ================================================== */
@@ -92,7 +106,7 @@ handle_slew(struct timespec *raw, struct timespec *cooked, double dfreq,
 /* ================================================== */

 HCL_Instance
-HCL_CreateInstance(int min_samples, int max_samples, double min_separation)
+HCL_CreateInstance(int min_samples, int max_samples, double min_separation, double precision)
 {
  HCL_Instance clock;

@@ -110,6 +124,10 @@ HCL_CreateInstance(int min_samples, int max_samples, double min_separation)
  clock->n_samples = 0;
  clock->valid_coefs = 0;
  clock->min_separation = min_separation;
+  clock->precision = precision;
+  clock->delay_quants = QNT_CreateInstance(DELAY_QUANT_MIN_K, DELAY_QUANT_MAX_K,
+                                           DELAY_QUANT_Q, DELAY_QUANT_REPEAT,
+                                           DELAY_QUANT_MIN_STEP);

  LCL_AddParameterChangeHandler(handle_slew, clock);

@@ -121,6 +139,7 @@ HCL_CreateInstance(int min_samples, int max_samples, double min_separation)
 void HCL_DestroyInstance(HCL_Instance clock)
 {
  LCL_RemoveParameterChangeHandler(handle_slew, clock);
+  QNT_DestroyInstance(clock->delay_quants);
  Free(clock->y_data);
  Free(clock->x_data);
  Free(clock);
@@ -140,6 +159,94 @@ HCL_NeedsNewSample(HCL_Instance clock, struct timespec *now)

 /* ================================================== */

+int
+HCL_ProcessReadings(HCL_Instance clock, int n_readings, struct timespec tss[][3],
+                    struct timespec *hw_ts, struct timespec *local_ts, double *err)
+{
+  double delay, raw_delay, min_delay, low_delay, high_delay, e, pred_err;
+  double delay_sum, hw_sum, local_sum, local_prec, freq;
+  int i, min_reading, combined;
+  struct timespec ts1, ts2;
+
+  if (n_readings < 1)
+    return 0;
+
+  /* Work out the current correction multiplier needed to get cooked delays */
+  LCL_CookTime(&tss[0][0], &ts1, NULL);
+  LCL_CookTime(&tss[n_readings - 1][2], &ts2, NULL);
+  if (UTI_CompareTimespecs(&tss[0][0], &tss[n_readings - 1][2]) < 0)
+    freq = UTI_DiffTimespecsToDouble(&ts1, &ts2) /
+           UTI_DiffTimespecsToDouble(&tss[0][0], &tss[n_readings - 1][2]);
+  else
+    freq = 1.0;
+
+  for (i = 0; i < n_readings; i++) {
+    delay = freq * UTI_DiffTimespecsToDouble(&tss[i][2], &tss[i][0]);
+
+    if (delay < 0.0) {
+      /* Step in the middle of a reading? */
+      DEBUG_LOG("Bad reading delay=%e", delay);
+      return 0;
+    }
+
+    if (i == 0 || min_delay > delay) {
+      min_delay = delay;
+      min_reading = i;
+    }
+
+    QNT_Accumulate(clock->delay_quants, delay);
+  }
+
+  local_prec = LCL_GetSysPrecisionAsQuantum();
+
+  low_delay = QNT_GetQuantile(clock->delay_quants, DELAY_QUANT_MIN_K);
+  high_delay = QNT_GetQuantile(clock->delay_quants, DELAY_QUANT_MAX_K);
+  low_delay = MIN(low_delay, high_delay);
+  high_delay = MAX(high_delay, low_delay + local_prec);
+
+  /* Combine readings with delay in the expected interval */
+  for (i = combined = 0, delay_sum = hw_sum = local_sum = 0.0; i < n_readings; i++) {
+    raw_delay = UTI_DiffTimespecsToDouble(&tss[i][2], &tss[i][0]);
+    delay = freq * raw_delay;
+
+    if (delay < low_delay || delay > high_delay)
+      continue;
+
+    delay_sum += delay;
+    hw_sum += UTI_DiffTimespecsToDouble(&tss[i][1], &tss[0][1]);
+    local_sum += UTI_DiffTimespecsToDouble(&tss[i][0], &tss[0][0]) + raw_delay / 2.0;
+    combined++;
+  }
+
+  DEBUG_LOG("Combined %d readings lo=%e hi=%e", combined, low_delay, high_delay);
+
+  if (combined > 0) {
+    UTI_AddDoubleToTimespec(&tss[0][1], hw_sum / combined, hw_ts);
+    UTI_AddDoubleToTimespec(&tss[0][0], local_sum / combined, local_ts);
+    *err = MAX(delay_sum / combined / 2.0, clock->precision);
+    return 1;
+  }
+
+  /* Accept the reading with minimum delay if its interval does not contain
+     the current offset predicted from previous samples */
+
+  *hw_ts = tss[min_reading][1];
+  UTI_AddDoubleToTimespec(&tss[min_reading][0], min_delay / freq / 2.0, local_ts);
+  *err = MAX(min_delay / 2.0, clock->precision);
+
+  pred_err = 0.0;
+  LCL_CookTime(local_ts, &ts1, NULL);
+  if (!HCL_CookTime(clock, hw_ts, &ts2, &e) ||
+      ((pred_err = UTI_DiffTimespecsToDouble(&ts1, &ts2)) > *err)) {
+    DEBUG_LOG("Accepted reading err=%e prerr=%e", *err, pred_err);
+    return 1;
+  }
+
+  return 0;
+}
+
+/* ================================================== */
+
 void
 HCL_AccumulateSample(HCL_Instance clock, struct timespec *hw_ts,
                     struct timespec *local_ts, double err)
--- a/hwclock.h
+++ b/hwclock.h
@@ -30,7 +30,7 @@ typedef struct HCL_Instance_Record *HCL_Instance;

 /* Create a new HW clock instance */
 extern HCL_Instance HCL_CreateInstance(int min_samples, int max_samples,
-                                       double min_separation);
+                                       double min_separation, double precision);

 /* Destroy a HW clock instance */
 extern void HCL_DestroyInstance(HCL_Instance clock);
@@ -38,6 +38,11 @@ extern void HCL_DestroyInstance(HCL_Instance clock);
 /* Check if a new sample should be accumulated at this time */
 extern int HCL_NeedsNewSample(HCL_Instance clock, struct timespec *now);

+/* Process new readings of the HW clock in form of (sys, hw, sys) triplets and
+   produce a sample which can be accumulated */
+extern int HCL_ProcessReadings(HCL_Instance clock, int n_readings, struct timespec tss[][3],
+                               struct timespec *hw_ts, struct timespec *local_ts, double *err);
+
 /* Accumulate a new sample */
 extern void HCL_AccumulateSample(HCL_Instance clock, struct timespec *hw_ts,
                                 struct timespec *local_ts, double err);
--- a/keys.c
+++ b/keys.c
@@ -3,7 +3,7 @@

 **********************************************************************
 * Copyright (C) Richard P. Curnow  1997-2003
- * Copyright (C) Miroslav Lichvar  2012-2016
+ * Copyright (C) Miroslav Lichvar  2012-2016, 2019-2020
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
@@ -50,16 +50,16 @@ typedef enum {

 typedef struct {
  uint32_t id;
+  int type;
+  int length;
  KeyClass class;
  union {
    struct {
      unsigned char *value;
-      int length;
      int hash_id;
    } ntp_mac;
    CMC_Instance cmac;
  } data;
-  int auth_delay;
 } Key;

 static ARR_Instance keys;
@@ -121,38 +121,6 @@ get_key(unsigned int index)
  return ((Key *)ARR_GetElements(keys)) + index;
 }

-/* ================================================== */
-
-static int
-determine_hash_delay(uint32_t key_id)
-{
-  NTP_Packet pkt;
-  struct timespec before, after;
-  double diff, min_diff;
-  int i, nsecs;
-
-  memset(&pkt, 0, sizeof (pkt));
-
-  for (i = 0; i < 10; i++) {
-    LCL_ReadRawTime(&before);
-    KEY_GenerateAuth(key_id, (unsigned char *)&pkt, NTP_HEADER_LENGTH,
-                     (unsigned char *)&pkt + NTP_HEADER_LENGTH,
-                     sizeof (pkt) - NTP_HEADER_LENGTH);
-    LCL_ReadRawTime(&after);
-
-    diff = UTI_DiffTimespecsToDouble(&after, &before);
-
-    if (i == 0 || min_diff > diff)
-      min_diff = diff;
-  }
-
-  nsecs = 1.0e9 * min_diff;
-
-  DEBUG_LOG("authentication delay for key %"PRIu32": %d nsecs", key_id, nsecs);
-
-  return nsecs;
-}
-
 /* ================================================== */
 /* Decode key encoded in ASCII or HEX */

@@ -201,6 +169,8 @@ KEY_Reload(void)
  FILE *in;
  char line[2048], *key_file, *key_value;
  const char *key_type;
+  HSH_Algorithm hash_algorithm;
+  CMC_Algorithm cmac_algorithm;
  int hash_id;
  Key key;

@@ -212,6 +182,9 @@ KEY_Reload(void)
  if (!key_file)
    return;

+  if (!UTI_CheckFilePermissions(key_file, 0771))
+    ;
+
  in = UTI_OpenFile(NULL, key_file, NULL, 'r', 0);
  if (!in) {
    LOG(LOGS_WARN, "Could not open keyfile %s", key_file);
@@ -238,27 +211,40 @@ KEY_Reload(void)
      continue;
    }

-    hash_id = HSH_GetHashId(key_type);
-    cmac_key_length = CMC_GetKeyLength(key_type);
+    hash_algorithm = UTI_HashNameToAlgorithm(key_type);
+    cmac_algorithm = UTI_CmacNameToAlgorithm(key_type);

-    if (hash_id >= 0) {
+    if (hash_algorithm != 0) {
+      hash_id = HSH_GetHashId(hash_algorithm);
+      if (hash_id < 0) {
+        LOG(LOGS_WARN, "Unsupported %s in key %"PRIu32, "hash function", key.id);
+        continue;
+      }
      key.class = NTP_MAC;
+      key.type = hash_algorithm;
+      key.length = key_length;
      key.data.ntp_mac.value = MallocArray(unsigned char, key_length);
      memcpy(key.data.ntp_mac.value, key_value, key_length);
-      key.data.ntp_mac.length = key_length;
      key.data.ntp_mac.hash_id = hash_id;
-    } else if (cmac_key_length > 0) {
-      if (cmac_key_length != key_length) {
+    } else if (cmac_algorithm != 0) {
+      cmac_key_length = CMC_GetKeyLength(cmac_algorithm);
+      if (cmac_key_length == 0) {
+        LOG(LOGS_WARN, "Unsupported %s in key %"PRIu32, "cipher", key.id);
+        continue;
+      } else if (cmac_key_length != key_length) {
        LOG(LOGS_WARN, "Invalid length of %s key %"PRIu32" (expected %u bits)",
            key_type, key.id, 8 * cmac_key_length);
        continue;
      }

      key.class = CMAC;
-      key.data.cmac = CMC_CreateInstance(key_type, (unsigned char *)key_value, key_length);
+      key.type = cmac_algorithm;
+      key.length = key_length;
+      key.data.cmac = CMC_CreateInstance(cmac_algorithm, (unsigned char *)key_value,
+                                         key_length);
      assert(key.data.cmac);
    } else {
-      LOG(LOGS_WARN, "Unknown hash function or cipher in key %"PRIu32, key.id);
+      LOG(LOGS_WARN, "Invalid type in key %"PRIu32, key.id);
      continue;
    }

@@ -272,6 +258,8 @@ KEY_Reload(void)
     more careful! */
  qsort(ARR_GetElements(keys), ARR_GetSize(keys), sizeof (Key), compare_keys_by_id);

+  LOG(LOGS_INFO, "Loaded %u symmetric keys", ARR_GetSize(keys));
+
  /* Check for duplicates */
  for (i = 1; i < ARR_GetSize(keys); i++) {
    if (get_key(i - 1)->id == get_key(i)->id)
@@ -280,9 +268,6 @@ KEY_Reload(void)

  /* Erase any passwords from stack */
  memset(line, 0, sizeof (line));
-
-  for (i = 0; i < ARR_GetSize(keys); i++)
-    get_key(i)->auth_delay = determine_hash_delay(get_key(i)->id);
 }

 /* ================================================== */
@@ -338,21 +323,6 @@ KEY_KeyKnown(uint32_t key_id)

 /* ================================================== */

-int
-KEY_GetAuthDelay(uint32_t key_id)
-{
-  Key *key;
-
-  key = get_key_by_id(key_id);
-
-  if (!key)
-    return 0;
-
-  return key->auth_delay;
-}
-
-/* ================================================== */
-
 int
 KEY_GetAuthLength(uint32_t key_id)
 {
@@ -387,24 +357,36 @@ KEY_CheckKeyLength(uint32_t key_id)
  if (!key)
    return 0;

-  switch (key->class) {
-    case NTP_MAC:
-      return key->data.ntp_mac.length >= MIN_SECURE_KEY_LENGTH;
-    default:
-      return 1;
-  }
+  return key->length >= MIN_SECURE_KEY_LENGTH;
+}
+
+/* ================================================== */
+
+int
+KEY_GetKeyInfo(uint32_t key_id, int *type, int *bits)
+{
+  Key *key;
+
+  key = get_key_by_id(key_id);
+
+  if (!key)
+    return 0;
+
+  *type = key->type;
+  *bits = 8 * key->length;
+
+  return 1;
 }

 /* ================================================== */

 static int
-generate_auth(Key *key, const unsigned char *data, int data_len,
-              unsigned char *auth, int auth_len)
+generate_auth(Key *key, const void *data, int data_len, unsigned char *auth, int auth_len)
 {
  switch (key->class) {
    case NTP_MAC:
      return HSH_Hash(key->data.ntp_mac.hash_id, key->data.ntp_mac.value,
-                      key->data.ntp_mac.length, data, data_len, auth, auth_len);
+                      key->length, data, data_len, auth, auth_len);
    case CMAC:
      return CMC_Hash(key->data.cmac, data, data_len, auth, auth_len);
    default:
@@ -415,7 +397,7 @@ generate_auth(Key *key, const unsigned char *data, int data_len,
 /* ================================================== */

 static int
-check_auth(Key *key, const unsigned char *data, int data_len,
+check_auth(Key *key, const void *data, int data_len,
           const unsigned char *auth, int auth_len, int trunc_len)
 {
  unsigned char buf[MAX_HASH_LENGTH];
@@ -429,7 +411,7 @@ check_auth(Key *key, const unsigned char *data, int data_len,
 /* ================================================== */

 int
-KEY_GenerateAuth(uint32_t key_id, const unsigned char *data, int data_len,
+KEY_GenerateAuth(uint32_t key_id, const void *data, int data_len,
                 unsigned char *auth, int auth_len)
 {
  Key *key;
@@ -445,7 +427,7 @@ KEY_GenerateAuth(uint32_t key_id, const unsigned char *data, int data_len,
 /* ================================================== */

 int
-KEY_CheckAuth(uint32_t key_id, const unsigned char *data, int data_len,
+KEY_CheckAuth(uint32_t key_id, const void *data, int data_len,
              const unsigned char *auth, int auth_len, int trunc_len)
 {
  Key *key;
--- a/keys.h
+++ b/keys.h
@@ -34,15 +34,14 @@ extern void KEY_Finalise(void);

 extern void KEY_Reload(void);

-extern int KEY_GetKey(uint32_t key_id, char **key, int *len);
 extern int KEY_KeyKnown(uint32_t key_id);
-extern int KEY_GetAuthDelay(uint32_t key_id);
 extern int KEY_GetAuthLength(uint32_t key_id);
 extern int KEY_CheckKeyLength(uint32_t key_id);
+extern int KEY_GetKeyInfo(uint32_t key_id, int *type, int *bits);

-extern int KEY_GenerateAuth(uint32_t key_id, const unsigned char *data,
-    int data_len, unsigned char *auth, int auth_len);
-extern int KEY_CheckAuth(uint32_t key_id, const unsigned char *data, int data_len,
+extern int KEY_GenerateAuth(uint32_t key_id, const void *data, int data_len,
+                            unsigned char *auth, int auth_len);
+extern int KEY_CheckAuth(uint32_t key_id, const void *data, int data_len,
                         const unsigned char *auth, int auth_len, int trunc_len);

 #endif /* GOT_KEYS_H */
--- a/local.c
+++ b/local.c
@@ -108,8 +108,8 @@ static double max_clock_error;

 #define NSEC_PER_SEC 1000000000

-static void
-calculate_sys_precision(void)
+static double
+measure_clock_precision(void)
 {
  struct timespec ts, old_ts;
  int iters, diff, best;
@@ -135,18 +135,7 @@ calculate_sys_precision(void)

  assert(best > 0);

-  precision_quantum = 1.0e-9 * best;
-
-  /* Get rounded log2 value of the measured precision */
-  precision_log = 0;
-  while (best < 707106781) {
-    precision_log--;
-    best *= 2;
-  }
-
-  assert(precision_log >= -30);
-
-  DEBUG_LOG("Clock precision %.9f (%d)", precision_quantum, precision_log);
+  return 1.0e-9 * best;
 }

 /* ================================================== */
@@ -170,7 +159,16 @@ LCL_Initialise(void)
  current_freq_ppm = 0.0;
  temp_comp_ppm = 0.0;

-  calculate_sys_precision();
+  precision_quantum = CNF_GetClockPrecision();
+  if (precision_quantum <= 0.0)
+    precision_quantum = measure_clock_precision();
+
+  precision_quantum = CLAMP(1.0e-9, precision_quantum, 1.0);
+  precision_log = round(log(precision_quantum) / log(2.0));
+  /* NTP code doesn't support smaller log than -30 */
+  assert(precision_log >= -30);
+
+  DEBUG_LOG("Clock precision %.9f (%d)", precision_quantum, precision_log);

  /* This is the maximum allowed frequency offset in ppm, the time must
     never stop or run backwards */
@@ -185,13 +183,11 @@ LCL_Initialise(void)
 void
 LCL_Finalise(void)
 {
-  while (change_list.next != &change_list)
-    LCL_RemoveParameterChangeHandler(change_list.next->handler,
-                                     change_list.next->anything);
-
-  while (dispersion_notify_list.next != &dispersion_notify_list)
-    LCL_RemoveDispersionNotifyHandler(dispersion_notify_list.next->handler,
-                                      dispersion_notify_list.next->anything);
+  /* Make sure all handlers have been removed */
+  if (change_list.next != &change_list)
+    assert(0);
+  if (dispersion_notify_list.next != &dispersion_notify_list)
+    assert(0);
 }

 /* ================================================== */
@@ -509,7 +505,7 @@ LCL_AccumulateDeltaFrequency(double dfreq)

 /* ================================================== */

-void
+int
 LCL_AccumulateOffset(double offset, double corr_rate)
 {
  struct timespec raw, cooked;
@@ -521,12 +517,14 @@ LCL_AccumulateOffset(double offset, double corr_rate)
  LCL_CookTime(&raw, &cooked, NULL);

  if (!check_offset(&cooked, offset))
-      return;
+    return 0;

  (*drv_accrue_offset)(offset, corr_rate);

  /* Dispatch to all handlers */
  invoke_parameter_change_handlers(&raw, &cooked, 0.0, offset, LCL_ChangeAdjust);
+
+  return 1;
 }

 /* ================================================== */
@@ -565,6 +563,8 @@ void
 LCL_NotifyExternalTimeStep(struct timespec *raw, struct timespec *cooked,
    double offset, double dispersion)
 {
+  LCL_CancelOffsetCorrection();
+
  /* Dispatch to all handlers */
  invoke_parameter_change_handlers(raw, cooked, 0.0, offset, LCL_ChangeUnknownStep);

@@ -590,7 +590,7 @@ LCL_NotifyLeap(int leap)

 /* ================================================== */

-void
+int
 LCL_AccumulateFrequencyAndOffset(double dfreq, double doffset, double corr_rate)
 {
  struct timespec raw, cooked;
@@ -602,7 +602,7 @@ LCL_AccumulateFrequencyAndOffset(double dfreq, double doffset, double corr_rate)
  LCL_CookTime(&raw, &cooked, NULL);

  if (!check_offset(&cooked, doffset))
-      return;
+    return 0;

  old_freq_ppm = current_freq_ppm;

@@ -624,6 +624,26 @@ LCL_AccumulateFrequencyAndOffset(double dfreq, double doffset, double corr_rate)

  /* Dispatch to all handlers */
  invoke_parameter_change_handlers(&raw, &cooked, dfreq, doffset, LCL_ChangeAdjust);
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+LCL_AccumulateFrequencyAndOffsetNoHandlers(double dfreq, double doffset, double corr_rate)
+{
+  ChangeListEntry *first_handler;
+  int r;
+
+  first_handler = change_list.next;
+  change_list.next = &change_list;
+
+  r = LCL_AccumulateFrequencyAndOffset(dfreq, doffset, corr_rate);
+
+  change_list.next = first_handler;
+
+  return r;
 }

 /* ================================================== */
@@ -691,6 +711,19 @@ LCL_MakeStep(void)

 /* ================================================== */

+void
+LCL_CancelOffsetCorrection(void)
+{
+  struct timespec raw;
+  double correction;
+
+  LCL_ReadRawTime(&raw);
+  LCL_GetOffsetCorrection(&raw, &correction, NULL);
+  LCL_AccumulateOffset(correction, 0.0);
+}
+
+/* ================================================== */
+
 int
 LCL_CanSystemLeap(void)
 {
--- a/local.h
+++ b/local.h
@@ -149,7 +149,7 @@ extern void LCL_AccumulateDeltaFrequency(double dfreq);
   forwards (i.e. it is currently slow of true time).  Provided is also
   a suggested correction rate (correction time * offset). */

-extern void LCL_AccumulateOffset(double offset, double corr_rate);
+extern int LCL_AccumulateOffset(double offset, double corr_rate);

 /* Routine to apply an immediate offset by doing a sudden step if
   possible. (Intended for use after an initial estimate of offset has
@@ -171,7 +171,12 @@ extern void LCL_NotifyLeap(int leap);

 /* Perform the combination of modifying the frequency and applying
   a slew, in one easy step */
-extern void LCL_AccumulateFrequencyAndOffset(double dfreq, double doffset, double corr_rate);
+extern int LCL_AccumulateFrequencyAndOffset(double dfreq, double doffset, double corr_rate);
+
+/* Same as the routine above, except it does not call the registered
+   parameter change handlers */
+extern int LCL_AccumulateFrequencyAndOffsetNoHandlers(double dfreq, double doffset,
+                                                      double corr_rate);

 /* Routine to read the system precision as a log to base 2 value. */
 extern int LCL_GetSysPrecisionAsLog(void);
@@ -197,6 +202,9 @@ extern void LCL_Finalise(void);
   to a timezone problem. */
 extern int LCL_MakeStep(void);

+/* Routine to cancel the outstanding system clock correction */
+extern void LCL_CancelOffsetCorrection(void);
+
 /* Check if the system driver supports leap seconds, i.e. LCL_SetSystemLeap
   does something */
 extern int LCL_CanSystemLeap(void);
--- a/logging.c
+++ b/logging.c
@@ -3,7 +3,7 @@

 **********************************************************************
 * Copyright (C) Richard P. Curnow  1997-2003
- * Copyright (C) Miroslav Lichvar  2011-2014, 2018
+ * Copyright (C) Miroslav Lichvar  2011-2014, 2018-2020
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
@@ -33,11 +33,15 @@

 #include "conf.h"
 #include "logging.h"
+#include "memory.h"
 #include "util.h"

 /* This is used by DEBUG_LOG macro */
 LOG_Severity log_min_severity = LOGS_INFO;

+/* Current logging contexts */
+static LOG_Context log_contexts;
+
 /* ================================================== */
 /* Flag indicating we have initialised */
 static int initialised = 0;
@@ -61,12 +65,18 @@ static int n_filelogs = 0;

 static struct LogFile logfiles[MAX_FILELOGS];

+/* Global prefix for debug messages */
+static char *debug_prefix;
+
 /* ================================================== */
 /* Init function */

 void
 LOG_Initialise(void)
 {
+  debug_prefix = Strdup("");
+  log_contexts = 0;
+
  initialised = 1;
  LOG_OpenFileLog(NULL);
 }
@@ -85,6 +95,8 @@ LOG_Finalise(void)

  LOG_CycleLogFiles();

+  Free(debug_prefix);
+
  initialised = 0;
 }

@@ -132,6 +144,8 @@ void LOG_Message(LOG_Severity severity,
  time_t t;
  struct tm *tm;

+  assert(initialised);
+
  if (!system_log && file_log && severity >= log_min_severity) {
    /* Don't clutter up syslog with timestamps and internal debugging info */
    time(&t);
@@ -142,7 +156,7 @@ void LOG_Message(LOG_Severity severity,
    }
 #if DEBUG > 0
    if (log_min_severity <= LOGS_DEBUG)
-      fprintf(file_log, "%s:%d:(%s) ", filename, line_number, function_name);
+      fprintf(file_log, "%s%s:%d:(%s) ", debug_prefix, filename, line_number, function_name);
 #endif
  }

@@ -220,6 +234,47 @@ void LOG_SetMinSeverity(LOG_Severity severity)

 /* ================================================== */

+LOG_Severity
+LOG_GetMinSeverity(void)
+{
+  return log_min_severity;
+}
+
+/* ================================================== */
+
+void
+LOG_SetContext(LOG_Context context)
+{
+  log_contexts |= context;
+}
+
+/* ================================================== */
+
+void
+LOG_UnsetContext(LOG_Context context)
+{
+  log_contexts &= ~context;
+}
+
+/* ================================================== */
+
+LOG_Severity
+LOG_GetContextSeverity(LOG_Context contexts)
+{
+  return log_contexts & contexts ? LOGS_INFO : LOGS_DEBUG;
+}
+
+/* ================================================== */
+
+void
+LOG_SetDebugPrefix(const char *prefix)
+{
+  Free(debug_prefix);
+  debug_prefix = Strdup(prefix);
+}
+
+/* ================================================== */
+
 void
 LOG_SetParentFd(int fd)
 {
@@ -243,7 +298,10 @@ LOG_CloseParentFd()
 LOG_FileID
 LOG_FileOpen(const char *name, const char *banner)
 {
-  assert(n_filelogs < MAX_FILELOGS);
+  if (n_filelogs >= MAX_FILELOGS) {
+    assert(0);
+    return -1;
+  }

  logfiles[n_filelogs].name = name;
  logfiles[n_filelogs].banner = banner;
@@ -267,7 +325,7 @@ LOG_FileWrite(LOG_FileID id, const char *format, ...)
  if (!logfiles[id].file) {
    char *logdir = CNF_GetLogDir();

-    if (logdir[0] == '\0') {
+    if (!logdir) {
      LOG(LOGS_WARN, "logdir not specified");
      logfiles[id].name = NULL;
      return;
--- a/logging.h
+++ b/logging.h
@@ -97,6 +97,26 @@ extern void LOG_Message(LOG_Severity severity, const char *format, ...);
   prefixed with the filename, line number, and function name. */
 extern void LOG_SetMinSeverity(LOG_Severity severity);

+/* Get the minimum severity */
+extern LOG_Severity LOG_GetMinSeverity(void);
+
+/* Flags for info messages that should be logged only in specific contexts */
+typedef enum {
+  LOGC_Command = 1,
+  LOGC_SourceFile = 2,
+} LOG_Context;
+
+/* Modify current contexts */
+extern void LOG_SetContext(LOG_Context context);
+extern void LOG_UnsetContext(LOG_Context context);
+
+/* Get severity depending on the current active contexts: INFO if they contain
+   at least one of the specified contexts, DEBUG otherwise */
+extern LOG_Severity LOG_GetContextSeverity(LOG_Context contexts);
+
+/* Set a prefix for debug messages */
+extern void LOG_SetDebugPrefix(const char *prefix);
+
 /* Log messages to a file instead of stderr, or stderr again if NULL */
 extern void LOG_OpenFileLog(const char *log_file);

--- a/main.c
+++ b/main.c
@@ -4,7 +4,7 @@
 **********************************************************************
 * Copyright (C) Richard P. Curnow  1997-2003
 * Copyright (C) John G. Hasler  2009
- * Copyright (C) Miroslav Lichvar  2012-2018
+ * Copyright (C) Miroslav Lichvar  2012-2020
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
@@ -38,7 +38,6 @@
 #include "ntp_signd.h"
 #include "ntp_sources.h"
 #include "ntp_core.h"
-#include "nts_ke_client.h"
 #include "nts_ke_server.h"
 #include "nts_ntp_server.h"
 #include "socket.h"
@@ -77,11 +76,18 @@ static REF_Mode ref_mode = REF_ModeNormal;
 static void
 do_platform_checks(void)
 {
+  struct timespec ts;
+
  /* Require at least 32-bit integers, two's complement representation and
     the usual implementation of conversion of unsigned integers */
  assert(sizeof (int) >= 4);
  assert(-1 == ~0);
  assert((int32_t)4294967295U == (int32_t)-1);
+
+  /* Require time_t and tv_nsec in timespec to be signed */
+  ts.tv_sec = -1;
+  ts.tv_nsec = -1;
+  assert(ts.tv_sec < 0 && ts.tv_nsec < 0);
 }

 /* ================================================== */
@@ -91,7 +97,7 @@ delete_pidfile(void)
 {
  const char *pidfile = CNF_GetPidFile();

-  if (!pidfile[0])
+  if (!pidfile)
    return;

  if (!UTI_RemoveFile(NULL, pidfile, NULL))
@@ -105,9 +111,8 @@ MAI_CleanupAndExit(void)
 {
  if (!initialised) exit(exit_status);
  
-  if (CNF_GetDumpDir()[0] != '\0') {
-    SRC_DumpSources();
-  }
+  LCL_CancelOffsetCorrection();
+  SRC_DumpSources();

  /* Don't update clock when removing sources */
  REF_SetMode(REF_ModeIgnore);
@@ -116,7 +121,6 @@ MAI_CleanupAndExit(void)
  TMC_Finalise();
  MNL_Finalise();
  CLG_Finalise();
-  NKC_Finalise();
  NKS_Finalise();
  NNS_Finalise();
  NSD_Finalise();
@@ -125,13 +129,15 @@ MAI_CleanupAndExit(void)
  NCR_Finalise();
  NIO_Finalise();
  CAM_Finalise();
-  SCK_Finalise();
+
  KEY_Finalise();
  RCL_Finalise();
  SRC_Finalise();
  REF_Finalise();
  RTC_Finalise();
  SYS_Finalise();
+
+  SCK_Finalise();
  SCH_Finalise();
  LCL_Finalise();
  PRV_Finalise();
@@ -142,6 +148,8 @@ MAI_CleanupAndExit(void)
  HSH_Finalise();
  LOG_Finalise();

+  UTI_ResetGetRandomFunctions();
+
  exit(exit_status);
 }

@@ -150,7 +158,6 @@ MAI_CleanupAndExit(void)
 static void
 signal_cleanup(int x)
 {
-  if (!initialised) exit(0);
  SCH_QuitProgram();
 }

@@ -159,6 +166,8 @@ signal_cleanup(int x)
 static void
 quit_timeout(void *arg)
 {
+  LOG(LOGS_INFO, "Timeout reached");
+
  /* Return with non-zero status if the clock is not synchronised */
  exit_status = REF_GetOurStratum() >= NTP_MAX_STRATUM;
  SCH_QuitProgram();
@@ -186,7 +195,7 @@ ntp_source_resolving_end(void)
  NSR_AutoStartSources();

  /* Special modes can end only when sources update their reachability.
-     Give up immediatelly if there are no active sources. */
+     Give up immediately if there are no active sources. */
  if (ref_mode != REF_ModeNormal && !SRC_ActiveSources()) {
    REF_SetUnsynchronised();
  }
@@ -261,7 +270,7 @@ check_pidfile(void)
  FILE *in;
  int pid, count;
  
-  if (!pidfile[0])
+  if (!pidfile)
    return;

  in = UTI_OpenFile(NULL, pidfile, NULL, 'r', 0);
@@ -289,7 +298,7 @@ write_pidfile(void)
  const char *pidfile = CNF_GetPidFile();
  FILE *out;

-  if (!pidfile[0])
+  if (!pidfile)
    return;

  out = UTI_OpenFile(NULL, pidfile, NULL, 'W', 0644);
@@ -322,6 +331,9 @@ go_daemon(void)
    char message[1024];
    int r;

+    /* Don't exit before the 'parent' */
+    waitpid(pid, NULL, 0);
+
    close(pipefd[1]);
    r = read(pipefd[0], message, sizeof (message));
    if (r) {
@@ -344,7 +356,9 @@ go_daemon(void)
    if (pid < 0) {
      LOG_FATAL("fork() failed : %s", strerror(errno));
    } else if (pid > 0) {
-      exit(0); /* In the 'parent' */
+      /* In the 'parent' */
+      close(pipefd[1]);
+      exit(0);
    } else {
      /* In the child we want to leave running as the daemon */

@@ -377,8 +391,34 @@ go_daemon(void)
 static void
 print_help(const char *progname)
 {
-      printf("Usage: %s [-4|-6] [-n|-d] [-q|-Q] [-r] [-R] [-s] [-t TIMEOUT] [-f FILE|COMMAND...]\n",
-             progname);
+      printf("Usage: %s [OPTION]... [DIRECTIVE]...\n\n"
+             "Options:\n"
+             "  -4\t\tUse IPv4 addresses only\n"
+             "  -6\t\tUse IPv6 addresses only\n"
+             "  -f FILE\tSpecify configuration file (%s)\n"
+             "  -n\t\tDon't run as daemon\n"
+             "  -d\t\tDon't run as daemon and log to stderr\n"
+#if DEBUG > 0
+             "  -d -d\t\tEnable debug messages\n"
+#endif
+             "  -l FILE\tLog to file\n"
+             "  -L LEVEL\tSet logging threshold (0)\n"
+             "  -p\t\tPrint configuration and exit\n"
+             "  -q\t\tSet clock and exit\n"
+             "  -Q\t\tLog offset and exit\n"
+             "  -r\t\tReload dump files\n"
+             "  -R\t\tAdapt configuration for restart\n"
+             "  -s\t\tSet clock from RTC\n"
+             "  -t SECONDS\tExit after elapsed time\n"
+             "  -u USER\tSpecify user (%s)\n"
+             "  -U\t\tDon't check for root\n"
+             "  -F LEVEL\tSet system call filter level (0)\n"
+             "  -P PRIORITY\tSet process priority (0)\n"
+             "  -m\t\tLock memory\n"
+             "  -x\t\tDon't control clock\n"
+             "  -v, --version\tPrint version and exit\n"
+             "  -h, --help\tPrint usage and exit\n",
+             progname, DEFAULT_CONF_FILE, DEFAULT_USER);
 }

 /* ================================================== */
@@ -414,13 +454,13 @@ int main
  int do_init_rtc = 0, restarted = 0, client_only = 0, timeout = -1;
  int scfilter_level = 0, lock_memory = 0, sched_priority = 0;
  int clock_control = 1, system_log = 1, log_severity = LOGS_INFO;
-  int config_args = 0;
+  int user_check = 1, config_args = 0, print_config = 0;

  do_platform_checks();

  LOG_Initialise();

-  /* Parse (undocumented) long command-line options */
+  /* Parse long command-line options */
  for (optind = 1; optind < argc; optind++) {
    if (!strcmp("--help", argv[optind])) {
      print_help(progname);
@@ -434,7 +474,7 @@ int main
  optind = 1;

  /* Parse short command-line options */
-  while ((opt = getopt(argc, argv, "46df:F:hl:L:mnP:qQrRst:u:vx")) != -1) {
+  while ((opt = getopt(argc, argv, "46df:F:hl:L:mnpP:qQrRst:u:Uvx")) != -1) {
    switch (opt) {
      case '4':
      case '6':
@@ -463,6 +503,13 @@ int main
      case 'n':
        nofork = 1;
        break;
+      case 'p':
+        print_config = 1;
+        user_check = 0;
+        nofork = 1;
+        system_log = 0;
+        log_severity = LOGS_WARN;
+        break;
      case 'P':
        sched_priority = parse_int_arg(optarg);
        break;
@@ -476,6 +523,7 @@ int main
        ref_mode = REF_ModePrintOnce;
        nofork = 1;
        client_only = 1;
+        user_check = 0;
        clock_control = 0;
        system_log = 0;
        break;
@@ -494,6 +542,9 @@ int main
      case 'u':
        user = optarg;
        break;
+      case 'U':
+        user_check = 0;
+        break;
      case 'v':
        print_version();
        return 0;
@@ -506,7 +557,7 @@ int main
    }
  }

-  if (getuid() && !client_only)
+  if (user_check && getuid() != 0)
    LOG_FATAL("Not superuser");

  /* Turn into a daemon */
@@ -527,6 +578,8 @@ int main
  DNS_SetAddressFamily(address_family);

  CNF_Initialise(restarted, client_only);
+  if (print_config)
+    CNF_EnablePrint();

  /* Parse the config file or the remaining command line arguments */
  config_args = argc - optind;
@@ -537,6 +590,9 @@ int main
      CNF_ParseLine(NULL, config_args + optind - argc + 1, argv[optind]);
  }

+  if (print_config)
+    return 0;
+
  /* Check whether another chronyd may already be running */
  check_pidfile();

@@ -556,16 +612,20 @@ int main
  PRV_Initialise();
  LCL_Initialise();
  SCH_Initialise();
+  SCK_Initialise(address_family);
+
+  /* Start helper processes if needed */
+  NKS_PreInitialise(pw->pw_uid, pw->pw_gid, scfilter_level);
+
  SYS_Initialise(clock_control);
  RTC_Initialise(do_init_rtc);
  SRC_Initialise();
  RCL_Initialise();
  KEY_Initialise();
-  SCK_Initialise();

  /* Open privileged ports before dropping root */
-  CAM_Initialise(address_family);
-  NIO_Initialise(address_family);
+  CAM_Initialise();
+  NIO_Initialise();
  NCR_Initialise();
  CNF_SetupAccessRestrictions();

@@ -582,16 +642,22 @@ int main
  }

  /* Drop root privileges if the specified user has a non-zero UID */
-  if (!geteuid() && (pw->pw_uid || pw->pw_gid))
-    SYS_DropRoot(pw->pw_uid, pw->pw_gid);
+  if (!geteuid() && (pw->pw_uid || pw->pw_gid)) {
+    SYS_DropRoot(pw->pw_uid, pw->pw_gid, SYS_MAIN_PROCESS);
+
+    /* Warn if missing read access or having write access to keys */
+    CNF_CheckReadOnlyAccess();
+  }
+
+  if (!geteuid())
+    LOG(LOGS_WARN, "Running with root privileges");

  REF_Initialise();
  SST_Initialise();
  NSR_Initialise();
  NSD_Initialise();
  NNS_Initialise();
-  NKS_Initialise(scfilter_level);
-  NKC_Initialise();
+  NKS_Initialise();
  CLG_Initialise();
  MNL_Initialise();
  TMC_Initialise();
--- a/manual.c
+++ b/manual.c
@@ -92,6 +92,7 @@ MNL_Initialise(void)
 void
 MNL_Finalise(void)
 {
+  LCL_RemoveParameterChangeHandler(slew_samples, NULL);
 }

 /* ================================================== */
--- a/md5.c
+++ b/md5.c
@@ -117,8 +117,7 @@ inline UINT4 ROTATE_LEFT(UINT4 x, int n)
 /* The routine MD5Init initializes the message-digest context
   mdContext. All fields are set to zero.
 */
-void MD5Init (mdContext)
-MD5_CTX *mdContext;
+void MD5Init (MD5_CTX *mdContext)
 {
  mdContext->i[0] = mdContext->i[1] = (UINT4)0;

@@ -134,10 +133,7 @@ MD5_CTX *mdContext;
   account for the presence of each of the characters inBuf[0..inLen-1]
   in the message whose digest is being computed.
 */
-void MD5Update (mdContext, inBuf, inLen)
-MD5_CTX *mdContext;
-unsigned const char *inBuf;
-unsigned int inLen;
+void MD5Update (MD5_CTX *mdContext, unsigned const char *inBuf, unsigned int inLen)
 {
  UINT4 in[16];
  int mdi;
@@ -173,8 +169,7 @@ unsigned int inLen;
   ends with the desired message digest in mdContext->digest[0...15].
 */

-void MD5Final (mdContext)
-MD5_CTX *mdContext;
+void MD5Final (MD5_CTX *mdContext)
 {
  UINT4 in[16];
  int mdi;
@@ -214,9 +209,7 @@ MD5_CTX *mdContext;

 /* Basic MD5 step. Transforms buf based on in.
 */
-static void Transform (buf, in)
-UINT4 *buf;
-UINT4 *in;
+static void Transform (UINT4 *buf, UINT4 *in)
 {
  UINT4 a = buf[0], b = buf[1], c = buf[2], d = buf[3];

--- a/memory.c
+++ b/memory.c
@@ -47,8 +47,13 @@ Realloc(void *ptr, size_t size)
 {
  void *r;

+  if (size == 0) {
+    Free(ptr);
+    return NULL;
+  }
+
  r = realloc(ptr, size);
-  if (!r && size)
+  if (!r)
    LOG_FATAL("Could not allocate memory");

  return r;
--- a/nameserv.c
+++ b/nameserv.c
@@ -50,12 +50,24 @@ DNS_SetAddressFamily(int family)
 DNS_Status 
 DNS_Name2IPAddress(const char *name, IPAddr *ip_addrs, int max_addrs)
 {
-#ifdef HAVE_GETADDRINFO
  struct addrinfo hints, *res, *ai;
  int i, result;
+  IPAddr ip;

  max_addrs = MIN(max_addrs, DNS_MAX_ADDRESSES);

+  for (i = 0; i < max_addrs; i++)
+    ip_addrs[i].family = IPADDR_UNSPEC;
+
+  /* Avoid calling getaddrinfo() if the name is an IP address */
+  if (UTI_StringToIP(name, &ip)) {
+    if (address_family != IPADDR_UNSPEC && ip.family != address_family)
+      return DNS_Failure;
+    if (max_addrs >= 1)
+      ip_addrs[0] = ip;
+    return DNS_Success;
+  }
+
  memset(&hints, 0, sizeof (hints));

  switch (address_family) {
@@ -95,6 +107,9 @@ DNS_Name2IPAddress(const char *name, IPAddr *ip_addrs, int max_addrs)
      case AF_INET6:
        if (address_family != IPADDR_UNSPEC && address_family != IPADDR_INET6)
          continue;
+        /* Don't return an address that would lose a scope ID */
+        if (((struct sockaddr_in6 *)ai->ai_addr)->sin6_scope_id != 0)
+          continue;
        ip_addrs[i].family = IPADDR_INET6;
        memcpy(&ip_addrs[i].addr.in6, &((struct sockaddr_in6 *)ai->ai_addr)->sin6_addr.s6_addr,
               sizeof (ip_addrs->addr.in6));
@@ -104,48 +119,9 @@ DNS_Name2IPAddress(const char *name, IPAddr *ip_addrs, int max_addrs)
    }
  }

-  for (; i < max_addrs; i++)
-        ip_addrs[i].family = IPADDR_UNSPEC;
-
  freeaddrinfo(res);

  return !max_addrs || ip_addrs[0].family != IPADDR_UNSPEC ? DNS_Success : DNS_Failure;
-#else
-  struct hostent *host;
-  int i;
-  
-  if (address_family != IPADDR_UNSPEC && address_family != IPADDR_INET4)
-    return DNS_Failure;
-
-  max_addrs = MIN(max_addrs, DNS_MAX_ADDRESSES);
-
-  host = gethostbyname(name);
-
-  if (host == NULL) {
-    if (h_errno == TRY_AGAIN)
-      return DNS_TryAgain;
-  } else {
-    if (host->h_addrtype != AF_INET || !host->h_addr_list[0])
-      return DNS_Failure;
-
-    for (i = 0; host->h_addr_list[i] && i < max_addrs; i++) {
-      ip_addrs[i].family = IPADDR_INET4;
-      ip_addrs[i].addr.in4 = ntohl(*(uint32_t *)host->h_addr_list[i]);
-    }
-
-    for (; i < max_addrs; i++)
-      ip_addrs[i].family = IPADDR_UNSPEC;
-
-    return DNS_Success;
-  }
-
-#ifdef FORCE_DNSRETRY
-  return DNS_TryAgain;
-#else
-  return DNS_Failure;
-#endif
-
-#endif
 }

 /* ================================================== */
@@ -154,9 +130,11 @@ int
 DNS_IPAddress2Name(IPAddr *ip_addr, char *name, int len)
 {
  char *result = NULL;
-
 #ifdef FEAT_IPV6
-  struct sockaddr_in6 in6;
+  struct sockaddr_in6 saddr;
+#else
+  struct sockaddr_in saddr;
+#endif
  IPSockAddr ip_saddr;
  socklen_t slen;
  char hbuf[NI_MAXHOST];
@@ -164,29 +142,9 @@ DNS_IPAddress2Name(IPAddr *ip_addr, char *name, int len)
  ip_saddr.ip_addr = *ip_addr;
  ip_saddr.port = 0;

-  slen = SCK_IPSockAddrToSockaddr(&ip_saddr, (struct sockaddr *)&in6, sizeof (in6));
-  if (!getnameinfo((struct sockaddr *)&in6, slen, hbuf, sizeof (hbuf), NULL, 0, 0))
+  slen = SCK_IPSockAddrToSockaddr(&ip_saddr, (struct sockaddr *)&saddr, sizeof (saddr));
+  if (!getnameinfo((struct sockaddr *)&saddr, slen, hbuf, sizeof (hbuf), NULL, 0, 0))
    result = hbuf;
-#else
-  struct hostent *host;
-  uint32_t addr;
-
-  switch (ip_addr->family) {
-    case IPADDR_INET4:
-      addr = htonl(ip_addr->addr.in4);
-      host = gethostbyaddr((const char *) &addr, sizeof (ip_addr), AF_INET);
-      break;
-#ifdef FEAT_IPV6
-    case IPADDR_INET6:
-      host = gethostbyaddr((const void *) ip_addr->addr.in6, sizeof (ip_addr->addr.in6), AF_INET6);
-      break;
-#endif
-    default:
-      host = NULL;
-  }
-  if (host)
-    result = host->h_name;
-#endif

  if (result == NULL)
    result = UTI_IPToString(ip_addr);
--- a/ntp.h
+++ b/ntp.h
@@ -113,13 +113,38 @@ typedef struct {
 #define NTP_REFID_LOCAL 0x7F7F0101UL /* 127.127.1.1 */
 #define NTP_REFID_SMOOTH 0x7F7F01FFUL /* 127.127.1.255 */

+/* Non-authentication extension fields and corresponding internal flags */
+
+#define NTP_EF_EXP1                     0xF323
+
+#define NTP_EF_FLAG_EXP1                0x1
+
+/* Pre-NTPv5 experimental extension field */
+typedef struct {
+  uint32_t magic;
+  NTP_int32 root_delay;
+  NTP_int32 root_dispersion;
+  NTP_int64 mono_receive_ts;
+  uint32_t mono_epoch;
+} NTP_ExtFieldExp1;
+
+#define NTP_EF_EXP1_MAGIC 0xF5BEDD9AU
+
+/* Authentication extension fields */
+
+#define NTP_EF_NTS_UNIQUE_IDENTIFIER    0x0104
+#define NTP_EF_NTS_COOKIE               0x0204
+#define NTP_EF_NTS_COOKIE_PLACEHOLDER   0x0304
+#define NTP_EF_NTS_AUTH_AND_EEF         0x0404
+
 /* Enumeration for authentication modes of NTP packets */
 typedef enum {
  NTP_AUTH_NONE = 0,            /* No authentication */
-  NTP_AUTH_SYMMETRIC,           /* MAC using symmetric key (RFC 1305, RFC 5905) */
+  NTP_AUTH_SYMMETRIC,           /* NTP MAC or CMAC using a symmetric key
+                                   (RFC 1305, RFC 5905, RFC 8573) */
  NTP_AUTH_MSSNTP,              /* MS-SNTP authenticator field */
  NTP_AUTH_MSSNTP_EXT,          /* MS-SNTP extended authenticator field */
-  NTP_AUTH_NTS,                 /* Network Time Security (RFC ????) */
+  NTP_AUTH_NTS,                 /* Network Time Security (RFC 8915) */
 } NTP_AuthMode;

 /* Structure describing an NTP packet */
@@ -129,6 +154,7 @@ typedef struct {
  NTP_Mode mode;

  int ext_fields;
+  int ext_field_flags;

  struct {
    NTP_AuthMode mode;
@@ -151,7 +177,13 @@ typedef struct {
  double peer_dispersion;
  double root_delay;
  double root_dispersion;
-  int stratum;
 } NTP_Sample;

+/* Possible sources of timestamps */
+typedef enum {
+  NTP_TS_DAEMON = 0,
+  NTP_TS_KERNEL,
+  NTP_TS_HARDWARE
+} NTP_Timestamp_Source;
+
 #endif /* GOT_NTP_H */
--- a/ntp_auth.c
+++ b/ntp_auth.c
@@ -2,7 +2,7 @@
  chronyd/chronyc - Programs for keeping computer clocks accurate.

 **********************************************************************
- * Copyright (C) Miroslav Lichvar  2019
+ * Copyright (C) Miroslav Lichvar  2019-2020
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
@@ -32,7 +32,6 @@
 #include "logging.h"
 #include "memory.h"
 #include "ntp_auth.h"
-#include "ntp_ext.h"
 #include "ntp_signd.h"
 #include "nts_ntp.h"
 #include "nts_ntp_client.h"
@@ -55,20 +54,29 @@ generate_symmetric_auth(uint32_t key_id, NTP_Packet *packet, NTP_PacketInfo *inf
 {
  int auth_len, max_auth_len;

+  if (info->length + NTP_MIN_MAC_LENGTH > sizeof (*packet)) {
+    DEBUG_LOG("Packet too long");
+    return 0;
+  }
+
  /* Truncate long MACs in NTPv4 packets to allow deterministic parsing
     of extension fields (RFC 7822) */
  max_auth_len = (info->version == 4 ? NTP_MAX_V4_MAC_LENGTH : NTP_MAX_MAC_LENGTH) - 4;
-  max_auth_len = MIN(max_auth_len, sizeof (NTP_Packet) - info->length - 4);
+  max_auth_len = MIN(max_auth_len, sizeof (*packet) - info->length - 4);

-  auth_len = KEY_GenerateAuth(key_id, (unsigned char *)packet, info->length,
+  auth_len = KEY_GenerateAuth(key_id, packet, info->length,
                              (unsigned char *)packet + info->length + 4, max_auth_len);
-  if (!auth_len) {
+  if (auth_len < NTP_MIN_MAC_LENGTH - 4) {
    DEBUG_LOG("Could not generate auth data with key %"PRIu32, key_id);
    return 0;
  }

  *(uint32_t *)((unsigned char *)packet + info->length) = htonl(key_id);
-  info->length += 4 + auth_len;
+
+  info->auth.mac.start = info->length;
+  info->auth.mac.length = 4 + auth_len;
+  info->auth.mac.key_id = key_id;
+  info->length += info->auth.mac.length;

  return 1;
 }
@@ -86,7 +94,7 @@ check_symmetric_auth(NTP_Packet *packet, NTP_PacketInfo *info)
  trunc_len = info->version == 4 && info->auth.mac.length <= NTP_MAX_V4_MAC_LENGTH ?
              NTP_MAX_V4_MAC_LENGTH : NTP_MAX_MAC_LENGTH;

-  if (!KEY_CheckAuth(info->auth.mac.key_id, (void *)packet, info->auth.mac.start,
+  if (!KEY_CheckAuth(info->auth.mac.key_id, packet, info->auth.mac.start,
                     (unsigned char *)packet + info->auth.mac.start + 4,
                     info->auth.mac.length - 4, trunc_len - 4))
    return 0;
@@ -96,37 +104,6 @@ check_symmetric_auth(NTP_Packet *packet, NTP_PacketInfo *info)

 /* ================================================== */

-static void
-adjust_timestamp(NTP_AuthMode mode, uint32_t key_id, struct timespec *ts)
-{
-  switch (mode) {
-    case NTP_AUTH_SYMMETRIC:
-      ts->tv_nsec += KEY_GetAuthDelay(key_id);
-      UTI_NormaliseTimespec(ts);
-      break;
-    case NTP_AUTH_MSSNTP:
-      ts->tv_nsec += NSD_GetAuthDelay(key_id);
-      UTI_NormaliseTimespec(ts);
-    default:
-      break;
-  }
-}
-
-/* ================================================== */
-
-static int
-is_zero_data(unsigned char *data, int length)
-{
-  int i;
-
-  for (i = 0; i < length; i++)
-    if (data[i])
-      return 0;
-  return 1;
-}
-
-/* ================================================== */
-
 static NAU_Instance
 create_instance(NTP_AuthMode mode)
 {
@@ -170,11 +147,12 @@ NAU_CreateSymmetricInstance(uint32_t key_id)
 /* ================================================== */

 NAU_Instance
-NAU_CreateNtsInstance(IPSockAddr *nts_address, const char *name, const IPSockAddr *ntp_address)
+NAU_CreateNtsInstance(IPSockAddr *nts_address, const char *name, uint32_t cert_set,
+                      uint16_t ntp_port)
 {
  NAU_Instance instance = create_instance(NTP_AUTH_NTS);

-  instance->nts = NNC_CreateInstance(nts_address, name, ntp_address);
+  instance->nts = NNC_CreateInstance(nts_address, name, cert_set, ntp_port);

  return instance;
 }
@@ -184,7 +162,7 @@ NAU_CreateNtsInstance(IPSockAddr *nts_address, const char *name, const IPSockAdd
 void
 NAU_DestroyInstance(NAU_Instance instance)
 {
-  if (instance->nts)
+  if (instance->mode == NTP_AUTH_NTS)
    NNC_DestroyInstance(instance->nts);
  Free(instance);
 }
@@ -230,14 +208,6 @@ NAU_PrepareRequestAuth(NAU_Instance instance)

 /* ================================================== */

-void
-NAU_AdjustRequestTimestamp(NAU_Instance instance, struct timespec *ts)
-{
-  adjust_timestamp(instance->mode, instance->key_id, ts);
-}
-
-/* ================================================== */
-
 int
 NAU_GenerateRequestAuth(NAU_Instance instance, NTP_Packet *request, NTP_PacketInfo *info)
 {
@@ -256,119 +226,13 @@ NAU_GenerateRequestAuth(NAU_Instance instance, NTP_Packet *request, NTP_PacketIn
      assert(0);
  }

+  info->auth.mode = instance->mode;
+
  return 1;
 }

 /* ================================================== */

-int
-NAU_ParsePacket(NTP_Packet *packet, NTP_PacketInfo *info)
-{
-  int parsed, remainder, ef_length, ef_type;
-  unsigned char *data;
-
-  data = (void *)packet;
-  parsed = NTP_HEADER_LENGTH;
-  remainder = info->length - parsed;
-
-  info->ext_fields = 0;
-
-  /* Check if this is a plain NTP packet with no extension fields or MAC */
-  if (remainder <= 0)
-    return 1;
-
-  /* In NTPv3 and older packets don't have extension fields.  Anything after
-     the header is assumed to be a MAC. */
-  if (info->version <= 3) {
-    info->auth.mode = NTP_AUTH_SYMMETRIC;
-    info->auth.mac.start = parsed;
-    info->auth.mac.length = remainder;
-    info->auth.mac.key_id = ntohl(*(uint32_t *)(data + parsed));
-
-    /* Check if it is an MS-SNTP authenticator field or extended authenticator
-       field with zeroes as digest */
-    if (info->version == 3 && info->auth.mac.key_id) {
-      if (remainder == 20 && is_zero_data(data + parsed + 4, remainder - 4))
-        info->auth.mode = NTP_AUTH_MSSNTP;
-      else if (remainder == 72 && is_zero_data(data + parsed + 8, remainder - 8))
-        info->auth.mode = NTP_AUTH_MSSNTP_EXT;
-    }
-
-    return 1;
-  }
-
-  /* Check for a crypto NAK */
-  if (remainder == 4 && ntohl(*(uint32_t *)(data + parsed)) == 0) {
-    info->auth.mode = NTP_AUTH_SYMMETRIC;
-    info->auth.mac.start = parsed;
-    info->auth.mac.length = remainder;
-    info->auth.mac.key_id = 0;
-    return 1;
-  }
-
-  /* Parse the rest of the NTPv4 packet */
-
-  while (remainder > 0) {
-    /* Check if the remaining data is a MAC */
-    if (remainder >= NTP_MIN_MAC_LENGTH && remainder <= NTP_MAX_V4_MAC_LENGTH)
-      break;
-
-    /* The NTPv4-specific limit for MAC length enables deterministic parsing of
-       packets with extension fields (RFC 7822), but we support longer MACs in
-       packets with no extension fields for compatibility with older chrony
-       clients.  Check if the longer MAC would authenticate the packet before
-       trying to parse the data as an extension field. */
-    if (parsed == NTP_HEADER_LENGTH &&
-        remainder > NTP_MAX_V4_MAC_LENGTH && remainder <= NTP_MAX_MAC_LENGTH &&
-        KEY_CheckAuth(ntohl(*(uint32_t *)(data + parsed)), data, parsed,
-                      (void *)(data + parsed + 4), remainder - 4, NTP_MAX_MAC_LENGTH - 4))
-      break;
-
-    /* Check if this is a valid NTPv4 extension field and skip it */
-    if (!NEF_ParseField(packet, info->length, parsed, &ef_length, &ef_type, NULL, NULL)) {
-      /* Invalid MAC or format error */
-      DEBUG_LOG("Invalid format or MAC");
-      return 0;
-    }
-
-    assert(ef_length > 0);
-
-    switch (ef_type) {
-      case NTP_EF_NTS_UNIQUE_IDENTIFIER:
-      case NTP_EF_NTS_COOKIE:
-      case NTP_EF_NTS_COOKIE_PLACEHOLDER:
-      case NTP_EF_NTS_AUTH_AND_EEF:
-        info->auth.mode = NTP_AUTH_NTS;
-        break;
-      default:
-        DEBUG_LOG("Unknown extension field type=%x", (unsigned int)ef_type);
-    }
-
-    info->ext_fields++;
-    parsed += ef_length;
-    remainder = info->length - parsed;
-  }
-
-  if (remainder == 0) {
-    /* No MAC */
-    return 1;
-  } else if (remainder >= NTP_MIN_MAC_LENGTH) {
-    /* This is not 100% reliable as a MAC could fail to authenticate and could
-       pass as an extension field, leaving reminder smaller than the minimum MAC
-       length */
-    info->auth.mode = NTP_AUTH_SYMMETRIC;
-    info->auth.mac.start = parsed;
-    info->auth.mac.length = remainder;
-    info->auth.mac.key_id = ntohl(*(uint32_t *)(data + parsed));
-    return 1;
-  }
-
-  DEBUG_LOG("Invalid format");
-  return 0;
-}
-
-/* ================================================== */
-
 int
 NAU_CheckRequestAuth(NTP_Packet *request, NTP_PacketInfo *info, uint32_t *kod)
 {
@@ -384,6 +248,9 @@ NAU_CheckRequestAuth(NTP_Packet *request, NTP_PacketInfo *info, uint32_t *kod)
    case NTP_AUTH_MSSNTP:
      /* MS-SNTP requests are not authenticated */
      break;
+    case NTP_AUTH_MSSNTP_EXT:
+      /* Not supported yet */
+      return 0;
    case NTP_AUTH_NTS:
      if (!NNS_CheckRequestAuth(request, info, kod))
        return 0;
@@ -397,14 +264,6 @@ NAU_CheckRequestAuth(NTP_Packet *request, NTP_PacketInfo *info, uint32_t *kod)

 /* ================================================== */

-void
-NAU_AdjustResponseTimestamp(NTP_Packet *request, NTP_PacketInfo *info, struct timespec *ts)
-{
-  adjust_timestamp(info->auth.mode, info->auth.mac.key_id, ts);
-}
-
-/* ================================================== */
-
 int
 NAU_GenerateResponseAuth(NTP_Packet *request, NTP_PacketInfo *request_info,
                         NTP_Packet *response, NTP_PacketInfo *response_info,
@@ -434,6 +293,8 @@ NAU_GenerateResponseAuth(NTP_Packet *request, NTP_PacketInfo *request_info,
      return 0;
  }

+  response_info->auth.mode = request_info->auth.mode;
+
  return 1;
 }

@@ -484,3 +345,42 @@ NAU_ChangeAddress(NAU_Instance instance, IPAddr *address)
      assert(0);
  }
 }
+
+/* ================================================== */
+
+void
+NAU_DumpData(NAU_Instance instance)
+{
+  switch (instance->mode) {
+    case NTP_AUTH_NTS:
+      NNC_DumpData(instance->nts);
+      break;
+    default:
+      break;
+  }
+}
+
+/* ================================================== */
+
+void
+NAU_GetReport(NAU_Instance instance, RPT_AuthReport *report)
+{
+  memset(report, 0, sizeof (*report));
+
+  report->mode = instance->mode;
+  report->last_ke_ago = -1;
+
+  switch (instance->mode) {
+    case NTP_AUTH_NONE:
+      break;
+    case NTP_AUTH_SYMMETRIC:
+      report->key_id = instance->key_id;
+      KEY_GetKeyInfo(instance->key_id, &report->key_type, &report->key_length);
+      break;
+    case NTP_AUTH_NTS:
+      NNC_GetReport(instance->nts, report);
+      break;
+    default:
+      assert(0);
+  }
+}
--- a/ntp_auth.h
+++ b/ntp_auth.h
@@ -29,6 +29,7 @@

 #include "addressing.h"
 #include "ntp.h"
+#include "reports.h"

 typedef struct NAU_Instance_Record *NAU_Instance;

@@ -36,7 +37,7 @@ typedef struct NAU_Instance_Record *NAU_Instance;
 extern NAU_Instance NAU_CreateNoneInstance(void);
 extern NAU_Instance NAU_CreateSymmetricInstance(uint32_t key_id);
 extern NAU_Instance NAU_CreateNtsInstance(IPSockAddr *nts_address, const char *name,
-                                          const IPSockAddr *ntp_address);
+                                          uint32_t cert_set, uint16_t ntp_port);

 /* Destroy an instance */
 extern void NAU_DestroyInstance(NAU_Instance instance);
@@ -50,26 +51,14 @@ extern int NAU_GetSuggestedNtpVersion(NAU_Instance instance);
 /* Perform operations necessary for NAU_GenerateRequestAuth() */
 extern int NAU_PrepareRequestAuth(NAU_Instance instance);

-/* Adjust a transmit timestamp for an estimated minimum time it takes to call
-   NAU_GenerateRequestAuth() */
-extern void NAU_AdjustRequestTimestamp(NAU_Instance instance, struct timespec *ts);
-
 /* Extend a request with data required by the authentication mode */
 extern int NAU_GenerateRequestAuth(NAU_Instance instance, NTP_Packet *request,
                                   NTP_PacketInfo *info);

-/* Parse a request or response to detect the authentication mode */
-extern int NAU_ParsePacket(NTP_Packet *packet, NTP_PacketInfo *info);
-
 /* Verify that a request is authentic.  If it is not authentic and a non-zero
   kod code is returned, a KoD response should be sent back. */
 extern int NAU_CheckRequestAuth(NTP_Packet *request, NTP_PacketInfo *info, uint32_t *kod);

-/* Adjust a transmit timestamp for an estimated minimum time it takes to call
-   NAU_GenerateResponseAuth() */
-extern void NAU_AdjustResponseTimestamp(NTP_Packet *request, NTP_PacketInfo *info,
-                                        struct timespec *ts);
-
 /* Extend a response with data required by the authentication mode.  This
   function can be called only if the previous call of NAU_CheckRequestAuth()
   was on the same request. */
@@ -86,4 +75,10 @@ extern int NAU_CheckResponseAuth(NAU_Instance instance, NTP_Packet *response,
 /* Change an authentication-specific address (e.g. after replacing a source) */
 extern void NAU_ChangeAddress(NAU_Instance instance, IPAddr *address);

+/* Save authentication-specific data to speed up the next start */
+extern void NAU_DumpData(NAU_Instance instance);
+
+/* Provide a report about the current authentication state */
+extern void NAU_GetReport(NAU_Instance instance, RPT_AuthReport *report);
+
 #endif
--- a/ntp_core.c
+++ b/ntp_core.c
--- a/ntp_core.h
+++ b/ntp_core.h
@@ -38,12 +38,6 @@ typedef enum {
  NTP_SERVER, NTP_PEER
 } NTP_Source_Type;

-typedef enum {
-  NTP_TS_DAEMON = 0,
-  NTP_TS_KERNEL,
-  NTP_TS_HARDWARE
-} NTP_Timestamp_Source;
-
 typedef struct {
  struct timespec ts;
  double err;
@@ -122,6 +116,7 @@ extern void NCR_ModifyPolltarget(NCR_Instance inst, int new_poll_target);
 extern void NCR_InitiateSampleBurst(NCR_Instance inst, int n_good_samples, int n_total_samples);

 extern void NCR_ReportSource(NCR_Instance inst, RPT_SourceReport *report, struct timespec *now);
+extern void NCR_GetAuthReport(NCR_Instance inst, RPT_AuthReport *report);
 extern void NCR_GetNTPReport(NCR_Instance inst, RPT_NTPReport *report);

 extern int NCR_AddAccessRestriction(IPAddr *ip_addr, int subnet_bits, int allow, int all);
@@ -136,6 +131,8 @@ extern uint32_t NCR_GetLocalRefid(NCR_Instance inst);

 extern int NCR_IsSyncPeer(NCR_Instance instance);

-extern void NCR_AddBroadcastDestination(IPAddr *addr, unsigned short port, int interval);
+extern void NCR_DumpAuthData(NCR_Instance inst);
+
+extern void NCR_AddBroadcastDestination(NTP_Remote_Address *addr, int interval);

 #endif /* GOT_NTP_CORE_H */
--- a/ntp_ext.c
+++ b/ntp_ext.c
@@ -2,7 +2,7 @@
  chronyd/chronyc - Programs for keeping computer clocks accurate.

 **********************************************************************
- * Copyright (C) Miroslav Lichvar  2019
+ * Copyright (C) Miroslav Lichvar  2019-2020
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
--- a/ntp_io.c
+++ b/ntp_io.c
@@ -4,7 +4,7 @@
 **********************************************************************
 * Copyright (C) Richard P. Curnow  1997-2003
 * Copyright (C) Timo Teras  2009
- * Copyright (C) Miroslav Lichvar  2009, 2013-2016, 2018
+ * Copyright (C) Miroslav Lichvar  2009, 2013-2016, 2018-2021
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
@@ -30,9 +30,11 @@

 #include "sysincl.h"

+#include "memory.h"
 #include "ntp_io.h"
 #include "ntp_core.h"
 #include "ntp_sources.h"
+#include "ptp.h"
 #include "sched.h"
 #include "socket.h"
 #include "local.h"
@@ -70,6 +72,16 @@ static int permanent_server_sockets;
 /* Flag indicating the server IPv4 socket is bound to an address */
 static int bound_server_sock_fd4;

+/* PTP event port, or 0 if disabled */
+static int ptp_port;
+
+/* Shared server/client sockets for NTP-over-PTP */
+static int ptp_sock_fd4;
+static int ptp_sock_fd6;
+
+/* Buffer for transmitted NTP-over-PTP messages */
+static PTP_NtpMessage *ptp_message;
+
 /* Flag indicating that we have been initialised */
 static int initialised=0;

@@ -83,19 +95,20 @@ static void read_from_socket(int sock_fd, int event, void *anything);
 static int
 open_socket(int family, int local_port, int client_only, IPSockAddr *remote_addr)
 {
-  int sock_fd, sock_flags, events = SCH_FILE_INPUT;
+  int sock_fd, sock_flags, dscp, events = SCH_FILE_INPUT;
  IPSockAddr local_addr;
+  char *iface;

-  if (!SCK_IsFamilySupported(family))
+  if (!SCK_IsIpFamilyEnabled(family))
    return INVALID_SOCK_FD;

-  if (!client_only)
+  if (!client_only) {
    CNF_GetBindAddress(family, &local_addr.ip_addr);
-  else
+    iface = CNF_GetBindNtpInterface();
+  } else {
    CNF_GetBindAcquisitionAddress(family, &local_addr.ip_addr);
-
-  if (local_addr.ip_addr.family != family)
-    SCK_GetAnyLocalIPAddress(family, &local_addr.ip_addr);
+    iface = CNF_GetBindAcquisitionInterface();
+  }

  local_addr.port = local_port;

@@ -103,13 +116,27 @@ open_socket(int family, int local_port, int client_only, IPSockAddr *remote_addr
  if (!client_only)
    sock_flags |= SCK_FLAG_BROADCAST;

-  sock_fd = SCK_OpenUdpSocket(remote_addr, &local_addr, sock_flags);
+  sock_fd = SCK_OpenUdpSocket(remote_addr, &local_addr, iface, sock_flags);
  if (sock_fd < 0) {
    if (!client_only)
      LOG(LOGS_ERR, "Could not open NTP socket on %s", UTI_IPSockAddrToString(&local_addr));
    return INVALID_SOCK_FD;
  }

+  dscp = CNF_GetNtpDscp();
+  if (dscp > 0 && dscp < 64) {
+#ifdef IP_TOS
+    if (family == IPADDR_INET4)
+      if (!SCK_SetIntOption(sock_fd, IPPROTO_IP, IP_TOS, dscp << 2))
+        ;
+#endif
+#if defined(FEAT_IPV6) && defined(IPV6_TCLASS)
+    if (family == IPADDR_INET6)
+      if (!SCK_SetIntOption(sock_fd, IPPROTO_IPV6, IPV6_TCLASS, dscp << 2))
+        ;
+#endif
+  }
+
  if (!client_only && family == IPADDR_INET4 && local_addr.port > 0)
    bound_server_sock_fd4 = local_addr.ip_addr.addr.in4 != INADDR_ANY;

@@ -142,9 +169,6 @@ close_socket(int sock_fd)
  if (sock_fd == INVALID_SOCK_FD)
    return;

-#ifdef HAVE_LINUX_TIMESTAMPING
-  NIO_Linux_NotifySocketClosing(sock_fd);
-#endif
  SCH_RemoveFileHandler(sock_fd);
  SCK_CloseSocket(sock_fd);
 }
@@ -152,7 +176,7 @@ close_socket(int sock_fd)
 /* ================================================== */

 void
-NIO_Initialise(int family)
+NIO_Initialise(void)
 {
  int server_port, client_port;

@@ -191,25 +215,18 @@ NIO_Initialise(int family)
  server_sock_ref4 = 0;
  server_sock_ref6 = 0;

-  if (family == IPADDR_UNSPEC || family == IPADDR_INET4) {
-    if (permanent_server_sockets && server_port)
-      server_sock_fd4 = open_socket(IPADDR_INET4, server_port, 0, NULL);
-    if (!separate_client_sockets) {
-      if (client_port != server_port || !server_port)
-        client_sock_fd4 = open_socket(IPADDR_INET4, client_port, 1, NULL);
-      else
-        client_sock_fd4 = server_sock_fd4;
-    }
+  if (permanent_server_sockets && server_port) {
+    server_sock_fd4 = open_socket(IPADDR_INET4, server_port, 0, NULL);
+    server_sock_fd6 = open_socket(IPADDR_INET6, server_port, 0, NULL);
  }

-  if (family == IPADDR_UNSPEC || family == IPADDR_INET6) {
-    if (permanent_server_sockets && server_port)
-      server_sock_fd6 = open_socket(IPADDR_INET6, server_port, 0, NULL);
-    if (!separate_client_sockets) {
-      if (client_port != server_port || !server_port)
-        client_sock_fd6 = open_socket(IPADDR_INET6, client_port, 1, NULL);
-      else
-        client_sock_fd6 = server_sock_fd6;
+  if (!separate_client_sockets) {
+    if (client_port != server_port || !server_port) {
+      client_sock_fd4 = open_socket(IPADDR_INET4, client_port, 1, NULL);
+      client_sock_fd6 = open_socket(IPADDR_INET6, client_port, 1, NULL);
+    } else {
+      client_sock_fd4 = server_sock_fd4;
+      client_sock_fd6 = server_sock_fd6;
    }
  }

@@ -219,6 +236,17 @@ NIO_Initialise(int family)
       client_sock_fd4 == INVALID_SOCK_FD && client_sock_fd6 == INVALID_SOCK_FD)) {
    LOG_FATAL("Could not open NTP sockets");
  }
+
+  ptp_port = CNF_GetPtpPort();
+  ptp_sock_fd4 = INVALID_SOCK_FD;
+  ptp_sock_fd6 = INVALID_SOCK_FD;
+  ptp_message = NULL;
+
+  if (ptp_port > 0) {
+    ptp_sock_fd4 = open_socket(IPADDR_INET4, ptp_port, 0, NULL);
+    ptp_sock_fd6 = open_socket(IPADDR_INET6, ptp_port, 0, NULL);
+    ptp_message = MallocNew(PTP_NtpMessage);
+  }
 }

 /* ================================================== */
@@ -236,6 +264,11 @@ NIO_Finalise(void)
  close_socket(server_sock_fd6);
  server_sock_fd6 = client_sock_fd6 = INVALID_SOCK_FD;

+  close_socket(ptp_sock_fd4);
+  close_socket(ptp_sock_fd6);
+  ptp_sock_fd4 = ptp_sock_fd6 = INVALID_SOCK_FD;
+  Free(ptp_message);
+
 #ifdef HAVE_LINUX_TIMESTAMPING
  NIO_Linux_Finalise();
 #endif
@@ -245,20 +278,36 @@ NIO_Finalise(void)

 /* ================================================== */

+int
+NIO_IsHwTsEnabled(void)
+{
+#ifdef HAVE_LINUX_TIMESTAMPING
+  return NIO_Linux_IsHwTsEnabled();
+#else
+  return 0;
+#endif
+}
+
+/* ================================================== */
+
 int
 NIO_OpenClientSocket(NTP_Remote_Address *remote_addr)
 {
-  if (separate_client_sockets) {
-    return open_separate_client_socket(remote_addr);
-  } else {
-    switch (remote_addr->ip_addr.family) {
-      case IPADDR_INET4:
-        return client_sock_fd4;
-      case IPADDR_INET6:
-        return client_sock_fd6;
-      default:
-        return INVALID_SOCK_FD;
-    }
+  switch (remote_addr->ip_addr.family) {
+    case IPADDR_INET4:
+      if (ptp_port > 0 && remote_addr->port == ptp_port)
+        return ptp_sock_fd4;
+      if (separate_client_sockets)
+        return open_separate_client_socket(remote_addr);
+      return client_sock_fd4;
+    case IPADDR_INET6:
+      if (ptp_port > 0 && remote_addr->port == ptp_port)
+        return ptp_sock_fd6;
+      if (separate_client_sockets)
+        return open_separate_client_socket(remote_addr);
+      return client_sock_fd6;
+    default:
+      return INVALID_SOCK_FD;
  }
 }

@@ -269,6 +318,8 @@ NIO_OpenServerSocket(NTP_Remote_Address *remote_addr)
 {
  switch (remote_addr->ip_addr.family) {
    case IPADDR_INET4:
+      if (ptp_port > 0 && remote_addr->port == ptp_port)
+        return ptp_sock_fd4;
      if (permanent_server_sockets)
        return server_sock_fd4;
      if (server_sock_fd4 == INVALID_SOCK_FD)
@@ -277,6 +328,8 @@ NIO_OpenServerSocket(NTP_Remote_Address *remote_addr)
        server_sock_ref4++;
      return server_sock_fd4;
    case IPADDR_INET6:
+      if (ptp_port > 0 && remote_addr->port == ptp_port)
+        return ptp_sock_fd6;
      if (permanent_server_sockets)
        return server_sock_fd6;
      if (server_sock_fd6 == INVALID_SOCK_FD)
@@ -291,9 +344,21 @@ NIO_OpenServerSocket(NTP_Remote_Address *remote_addr)

 /* ================================================== */

+static int
+is_ptp_socket(int sock_fd)
+{
+  return ptp_port > 0 && sock_fd != INVALID_SOCK_FD &&
+    (sock_fd == ptp_sock_fd4 || sock_fd == ptp_sock_fd6);
+}
+
+/* ================================================== */
+
 void
 NIO_CloseClientSocket(int sock_fd)
 {
+  if (is_ptp_socket(sock_fd))
+    return;
+
  if (separate_client_sockets)
    close_socket(sock_fd);
 }
@@ -303,7 +368,7 @@ NIO_CloseClientSocket(int sock_fd)
 void
 NIO_CloseServerSocket(int sock_fd)
 {
-  if (permanent_server_sockets || sock_fd == INVALID_SOCK_FD)
+  if (permanent_server_sockets || sock_fd == INVALID_SOCK_FD || is_ptp_socket(sock_fd))
    return;

  if (sock_fd == server_sock_fd4) {
@@ -327,7 +392,7 @@ int
 NIO_IsServerSocket(int sock_fd)
 {
  return sock_fd != INVALID_SOCK_FD &&
-    (sock_fd == server_sock_fd4 || sock_fd == server_sock_fd6);
+    (sock_fd == server_sock_fd4 || sock_fd == server_sock_fd6 || is_ptp_socket(sock_fd));
 }

 /* ================================================== */
@@ -335,7 +400,8 @@ NIO_IsServerSocket(int sock_fd)
 int
 NIO_IsServerSocketOpen(void)
 {
-  return server_sock_fd4 != INVALID_SOCK_FD || server_sock_fd6 != INVALID_SOCK_FD;
+  return server_sock_fd4 != INVALID_SOCK_FD || server_sock_fd6 != INVALID_SOCK_FD ||
+    ptp_sock_fd4 != INVALID_SOCK_FD || ptp_sock_fd6 != INVALID_SOCK_FD;
 }

 /* ================================================== */
@@ -390,6 +456,9 @@ process_message(SCK_Message *message, int sock_fd, int event)
    DEBUG_LOG("Updated RX timestamp delay=%.9f tss=%u",
              UTI_DiffTimespecsToDouble(&sched_ts, &local_ts.ts), local_ts.source);

+  if (!NIO_UnwrapMessage(message, sock_fd))
+    return;
+
  /* Just ignore the packet if it's not of a recognized length */
  if (message->length < NTP_HEADER_LENGTH || message->length > sizeof (NTP_Packet)) {
    DEBUG_LOG("Unexpected length");
@@ -404,17 +473,9 @@ process_message(SCK_Message *message, int sock_fd, int event)
 static void
 read_from_socket(int sock_fd, int event, void *anything)
 {
-  /* This should only be called when there is something
-     to read, otherwise it may block */
-
-  SCK_Message messages[SCK_MAX_RECV_MESSAGES];
+  SCK_Message *messages;
  int i, received, flags = 0;

-#ifdef HAVE_LINUX_TIMESTAMPING
-  if (NIO_Linux_ProcessEvent(sock_fd, event))
-    return;
-#endif
-
  if (event == SCH_FILE_EXCEPTION) {
 #ifdef HAVE_LINUX_TIMESTAMPING
    flags |= SCK_FLAG_MSG_ERRQUEUE;
@@ -423,14 +484,89 @@ read_from_socket(int sock_fd, int event, void *anything)
 #endif
  }

-  received = SCK_ReceiveMessages(sock_fd, messages, SCK_MAX_RECV_MESSAGES, flags);
-  if (received <= 0)
+  messages = SCK_ReceiveMessages(sock_fd, flags, &received);
+  if (!messages)
    return;

  for (i = 0; i < received; i++)
    process_message(&messages[i], sock_fd, event);
 }

+/* ================================================== */
+
+int
+NIO_UnwrapMessage(SCK_Message *message, int sock_fd)
+{
+  PTP_NtpMessage *msg;
+
+  if (!is_ptp_socket(sock_fd))
+    return 1;
+
+  if (message->length <= PTP_NTP_PREFIX_LENGTH) {
+    DEBUG_LOG("Unexpected length");
+    return 0;
+  }
+
+  msg = message->data;
+
+  if (msg->header.type != PTP_TYPE_DELAY_REQ || msg->header.version != PTP_VERSION ||
+      ntohs(msg->header.length) != message->length ||
+      msg->header.domain != PTP_DOMAIN_NTP ||
+      ntohs(msg->header.flags) != PTP_FLAG_UNICAST ||
+      ntohs(msg->tlv_header.type) != PTP_TLV_NTP ||
+      ntohs(msg->tlv_header.length) != message->length - PTP_NTP_PREFIX_LENGTH) {
+    DEBUG_LOG("Unexpected PTP message");
+    return 0;
+  }
+
+  message->data = (char *)message->data + PTP_NTP_PREFIX_LENGTH;
+  message->length -= PTP_NTP_PREFIX_LENGTH;
+
+  DEBUG_LOG("Unwrapped PTP->NTP len=%d", message->length);
+
+  return 1;
+}
+
+/* ================================================== */
+
+static int
+wrap_message(SCK_Message *message, int sock_fd)
+{
+  static uint16_t sequence_id = 0;
+
+  assert(PTP_NTP_PREFIX_LENGTH == 48);
+
+  if (!is_ptp_socket(sock_fd))
+    return 1;
+
+  if (!ptp_message)
+    return 0;
+
+  if (message->length < NTP_HEADER_LENGTH ||
+      message->length + PTP_NTP_PREFIX_LENGTH > sizeof (*ptp_message)) {
+    DEBUG_LOG("Unexpected length");
+    return 0;
+  }
+
+  memset(ptp_message, 0, PTP_NTP_PREFIX_LENGTH);
+  ptp_message->header.type = PTP_TYPE_DELAY_REQ;
+  ptp_message->header.version = PTP_VERSION;
+  ptp_message->header.length = htons(PTP_NTP_PREFIX_LENGTH + message->length);
+  ptp_message->header.domain = PTP_DOMAIN_NTP;
+  ptp_message->header.flags = htons(PTP_FLAG_UNICAST);
+  ptp_message->header.sequence_id = htons(sequence_id++);
+  ptp_message->tlv_header.type = htons(PTP_TLV_NTP);
+  ptp_message->tlv_header.length = htons(message->length);
+  memcpy((char *)ptp_message + PTP_NTP_PREFIX_LENGTH, message->data, message->length);
+
+  message->data = ptp_message;
+  message->length += PTP_NTP_PREFIX_LENGTH;
+
+  DEBUG_LOG("Wrapped NTP->PTP len=%d", message->length - PTP_NTP_PREFIX_LENGTH);
+
+  return 1;
+}
+
 /* ================================================== */
 /* Send a packet to remote address from local address */

@@ -452,19 +588,26 @@ NIO_SendPacket(NTP_Packet *packet, NTP_Remote_Address *remote_addr,
  message.data = packet;
  message.length = length;

+  if (!wrap_message(&message, local_addr->sock_fd))
+    return 0;
+
  /* Specify remote address if the socket is not connected */
  if (NIO_IsServerSocket(local_addr->sock_fd) || !separate_client_sockets) {
    message.remote_addr.ip.ip_addr = remote_addr->ip_addr;
    message.remote_addr.ip.port = remote_addr->port;
  }

-  message.if_index = local_addr->if_index;
  message.local_addr.ip = local_addr->ip_addr;

+  /* Don't require responses to non-link-local addresses to use the same
+     interface */
+  message.if_index = SCK_IsLinkLocalIPAddress(&message.remote_addr.ip.ip_addr) ?
+                       local_addr->if_index : INVALID_IF_INDEX;
+
 #if !defined(HAVE_IN_PKTINFO) && defined(IP_SENDSRCADDR)
  /* On FreeBSD a local IPv4 address cannot be specified on bound socket */
  if (message.local_addr.ip.family == IPADDR_INET4 &&
-      (local_addr->sock_fd != server_sock_fd4 || bound_server_sock_fd4))
+      (bound_server_sock_fd4 || !NIO_IsServerSocket(local_addr->sock_fd)))
    message.local_addr.ip.family = IPADDR_UNSPEC;
 #endif

--- a/ntp_io.h
+++ b/ntp_io.h
@@ -31,13 +31,17 @@

 #include "ntp.h"
 #include "addressing.h"
+#include "socket.h"

 /* Function to initialise the module. */
-extern void NIO_Initialise(int family);
+extern void NIO_Initialise(void);

 /* Function to finalise the module */
 extern void NIO_Finalise(void);

+/* Function to check if HW timestamping is enabled on any interface */
+extern int NIO_IsHwTsEnabled(void);
+
 /* Function to obtain a socket for sending client packets */
 extern int NIO_OpenClientSocket(NTP_Remote_Address *remote_addr);

@@ -59,6 +63,9 @@ extern int NIO_IsServerSocketOpen(void);
 /* Function to check if client packets can be sent to a server */
 extern int NIO_IsServerConnectable(NTP_Remote_Address *remote_addr);

+/* Function to unwrap an NTP message from non-native transport (e.g. PTP) */
+extern int NIO_UnwrapMessage(SCK_Message *message, int sock_fd);
+
 /* Function to transmit a packet */
 extern int NIO_SendPacket(NTP_Packet *packet, NTP_Remote_Address *remote_addr,
                          NTP_Local_Address *local_addr, int length, int process_tx);
--- a/ntp_io_linux.c
+++ b/ntp_io_linux.c
@@ -2,7 +2,7 @@
  chronyd/chronyc - Programs for keeping computer clocks accurate.

 **********************************************************************
- * Copyright (C) Miroslav Lichvar  2016-2019
+ * Copyright (C) Miroslav Lichvar  2016-2019, 2021-2023
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
@@ -39,6 +39,7 @@
 #include "hwclock.h"
 #include "local.h"
 #include "logging.h"
+#include "memory.h"
 #include "ntp_core.h"
 #include "ntp_io.h"
 #include "ntp_io_linux.h"
@@ -59,21 +60,22 @@ struct Interface {
  /* Start of UDP data at layer 2 for IPv4 and IPv6 */
  int l2_udp4_ntp_start;
  int l2_udp6_ntp_start;
-  /* Precision of PHC readings */
-  double precision;
  /* Compensation of errors in TX and RX timestamping */
  double tx_comp;
  double rx_comp;
  HCL_Instance clock;
+  int maxpoll;
+  SCH_TimeoutID poll_timeout_id;
 };

 /* Number of PHC readings per HW clock sample */
-#define PHC_READINGS 10
+#define PHC_READINGS 25

-/* Minimum interval between PHC readings */
+/* Minimum and maximum interval between PHC readings */
 #define MIN_PHC_POLL -6
+#define MAX_PHC_POLL 20

-/* Maximum acceptable offset between HW and daemon/kernel timestamp */
+/* Maximum acceptable offset between SW/HW and daemon timestamp */
 #define MAX_TS_DELAY 1.0

 /* Array of Interfaces */
@@ -86,19 +88,6 @@ static int ts_tx_flags;
 /* Flag indicating the socket options can't be changed in control messages */
 static int permanent_ts_options;

-/* When sending client requests to a close and fast server, it is possible that
-   a response will be received before the HW transmit timestamp of the request
-   itself.  To avoid processing of the response without the HW timestamp, we
-   monitor events returned by select() and suspend reading of packets from the
-   receive queue for up to 200 microseconds.  As the requests are normally
-   separated by at least 200 milliseconds, it is sufficient to monitor and
-   suspend one socket at a time. */
-static int monitored_socket;
-static int suspended_socket;
-static SCH_TimeoutID resume_timeout_id;
-
-#define RESUME_TIMEOUT 200.0e-6
-
 /* Unbound socket keeping the kernel RX timestamping permanently enabled
   in order to avoid a race condition between receiving a server response
   and the kernel actually starting to timestamp received packets after
@@ -109,13 +98,17 @@ static int dummy_rxts_socket;

 /* ================================================== */

+static void poll_phc(struct Interface *iface, struct timespec *now);
+
+/* ================================================== */
+
 static int
 add_interface(CNF_HwTsInterface *conf_iface)
 {
+  int sock_fd, if_index, minpoll, phc_fd, req_hwts_flags, rx_filter;
  struct ethtool_ts_info ts_info;
  struct hwtstamp_config ts_config;
  struct ifreq req;
-  int sock_fd, if_index, phc_fd, req_hwts_flags, rx_filter;
  unsigned int i;
  struct Interface *iface;

@@ -125,7 +118,7 @@ add_interface(CNF_HwTsInterface *conf_iface)
      return 1;
  }

-  sock_fd = SCK_OpenUdpSocket(NULL, NULL, 0);
+  sock_fd = SCK_OpenUdpSocket(NULL, NULL, NULL, 0);
  if (sock_fd < 0)
    return 0;

@@ -189,6 +182,14 @@ add_interface(CNF_HwTsInterface *conf_iface)
      rx_filter = HWTSTAMP_FILTER_NTP_ALL;
      break;
 #endif
+    case CNF_HWTS_RXFILTER_PTP:
+      if (ts_info.rx_filters & (1 << HWTSTAMP_FILTER_PTP_V2_L4_EVENT))
+        rx_filter = HWTSTAMP_FILTER_PTP_V2_L4_EVENT;
+      else if (ts_info.rx_filters & (1 << HWTSTAMP_FILTER_PTP_V2_EVENT))
+        rx_filter = HWTSTAMP_FILTER_PTP_V2_EVENT;
+      else
+        rx_filter = HWTSTAMP_FILTER_NONE;
+      break;
    default:
      rx_filter = HWTSTAMP_FILTER_ALL;
      break;
@@ -200,7 +201,8 @@ add_interface(CNF_HwTsInterface *conf_iface)
  req.ifr_data = (char *)&ts_config;

  if (ioctl(sock_fd, SIOCSHWTSTAMP, &req)) {
-    DEBUG_LOG("ioctl(%s) failed : %s", "SIOCSHWTSTAMP", strerror(errno));
+    LOG(errno == EPERM ? LOGS_ERR : LOGS_DEBUG,
+        "ioctl(%s) failed : %s", "SIOCSHWTSTAMP", strerror(errno));

    /* Check the current timestamping configuration in case this interface
       allows only reading of the configuration and it was already configured
@@ -235,12 +237,18 @@ add_interface(CNF_HwTsInterface *conf_iface)
  iface->l2_udp4_ntp_start = 42;
  iface->l2_udp6_ntp_start = 62;

-  iface->precision = conf_iface->precision;
  iface->tx_comp = conf_iface->tx_comp;
  iface->rx_comp = conf_iface->rx_comp;

+  minpoll = CLAMP(MIN_PHC_POLL, conf_iface->minpoll, MAX_PHC_POLL);
  iface->clock = HCL_CreateInstance(conf_iface->min_samples, conf_iface->max_samples,
-                                    UTI_Log2ToDouble(MAX(conf_iface->minpoll, MIN_PHC_POLL)));
+                                    UTI_Log2ToDouble(minpoll), conf_iface->precision);
+
+  iface->maxpoll = CLAMP(minpoll, conf_iface->maxpoll, MAX_PHC_POLL);
+
+  /* Do not schedule the first poll timeout here!  The argument (interface) can
+     move until all interfaces are added.  Wait for the first HW timestamp. */
+  iface->poll_timeout_id = 0;

  LOG(LOGS_INFO, "Enabled HW timestamping %son %s",
      ts_config.rx_filter == HWTSTAMP_FILTER_NONE ? "(TX only) " : "", iface->name);
@@ -285,7 +293,7 @@ update_interface_speed(struct Interface *iface)
  struct ifreq req;
  int sock_fd, link_speed;

-  sock_fd = SCK_OpenUdpSocket(NULL, NULL, 0);
+  sock_fd = SCK_OpenUdpSocket(NULL, NULL, NULL, 0);
  if (sock_fd < 0)
    return;

@@ -320,7 +328,7 @@ check_timestamping_option(int option)
 {
  int sock_fd;

-  sock_fd = SCK_OpenUdpSocket(NULL, NULL, 0);
+  sock_fd = SCK_OpenUdpSocket(NULL, NULL, NULL, 0);
  if (sock_fd < 0)
    return 0;

@@ -341,7 +349,7 @@ open_dummy_socket(void)
 {
  int sock_fd, events = 0;

-  sock_fd = SCK_OpenUdpSocket(NULL, NULL, 0);
+  sock_fd = SCK_OpenUdpSocket(NULL, NULL, NULL, 0);
  if (sock_fd < 0)
    return INVALID_SOCK_FD;

@@ -405,8 +413,6 @@ NIO_Linux_Initialise(void)
  /* Kernels before 4.7 ignore timestamping flags set in control messages */
  permanent_ts_options = !SYS_Linux_CheckKernelVersion(4, 7);

-  monitored_socket = INVALID_SOCK_FD;
-  suspended_socket = INVALID_SOCK_FD;
  dummy_rxts_socket = INVALID_SOCK_FD;
 }

@@ -423,6 +429,7 @@ NIO_Linux_Finalise(void)

  for (i = 0; i < ARR_GetSize(interfaces); i++) {
    iface = ARR_GetElement(interfaces, i);
+    SCH_RemoveTimeout(iface->poll_timeout_id);
    HCL_DestroyInstance(iface->clock);
    close(iface->phc_fd);
  }
@@ -432,6 +439,14 @@ NIO_Linux_Finalise(void)

 /* ================================================== */

+int
+NIO_Linux_IsHwTsEnabled(void)
+{
+  return ARR_GetSize(interfaces) > 0;
+}
+
+/* ================================================== */
+
 int
 NIO_Linux_SetTimestampSocketOptions(int sock_fd, int client_only, int *events)
 {
@@ -465,73 +480,6 @@ NIO_Linux_SetTimestampSocketOptions(int sock_fd, int client_only, int *events)

 /* ================================================== */

-static void
-resume_socket(int sock_fd)
-{
-  if (monitored_socket == sock_fd)
-    monitored_socket = INVALID_SOCK_FD;
-
-  if (sock_fd == INVALID_SOCK_FD || sock_fd != suspended_socket)
-    return;
-
-  suspended_socket = INVALID_SOCK_FD;
-
-  SCH_SetFileHandlerEvent(sock_fd, SCH_FILE_INPUT, 1);
-
-  DEBUG_LOG("Resumed RX processing %s timeout fd=%d",
-            resume_timeout_id ? "before" : "on", sock_fd);
-
-  if (resume_timeout_id) {
-    SCH_RemoveTimeout(resume_timeout_id);
-    resume_timeout_id = 0;
-  }
-}
-
-/* ================================================== */
-
-static void
-resume_timeout(void *arg)
-{
-  resume_timeout_id = 0;
-  resume_socket(suspended_socket);
-}
-
-/* ================================================== */
-
-static void
-suspend_socket(int sock_fd)
-{
-  resume_socket(suspended_socket);
-
-  suspended_socket = sock_fd;
-
-  SCH_SetFileHandlerEvent(suspended_socket, SCH_FILE_INPUT, 0);
-  resume_timeout_id = SCH_AddTimeoutByDelay(RESUME_TIMEOUT, resume_timeout, NULL);
-
-  DEBUG_LOG("Suspended RX processing fd=%d", sock_fd);
-}
-
-/* ================================================== */
-
-int
-NIO_Linux_ProcessEvent(int sock_fd, int event)
-{
-  if (sock_fd != monitored_socket)
-    return 0;
-
-  if (event == SCH_FILE_INPUT) {
-    suspend_socket(monitored_socket);
-    monitored_socket = INVALID_SOCK_FD;
-
-    /* Don't process the message yet */
-    return 1;
-  }
-
-  return 0;
-}
-
-/* ================================================== */
-
 static struct Interface *
 get_interface(int if_index)
 {
@@ -551,26 +499,70 @@ get_interface(int if_index)

 /* ================================================== */

+static void
+poll_timeout(void *arg)
+{
+  struct Interface *iface = arg;
+  struct timespec now;
+
+  iface->poll_timeout_id = 0;
+
+  SCH_GetLastEventTime(&now, NULL, NULL);
+  poll_phc(iface, &now);
+}
+
+/* ================================================== */
+
+static void
+poll_phc(struct Interface *iface, struct timespec *now)
+{
+  struct timespec sample_phc_ts, sample_sys_ts, sample_local_ts;
+  struct timespec phc_readings[PHC_READINGS][3];
+  double phc_err, local_err, interval;
+  int n_readings;
+
+  if (!HCL_NeedsNewSample(iface->clock, now))
+    return;
+
+  DEBUG_LOG("Polling PHC on %s%s",
+            iface->name, iface->poll_timeout_id != 0 ? " before timeout" : "");
+
+  n_readings = SYS_Linux_GetPHCReadings(iface->phc_fd, iface->phc_nocrossts,
+                                        &iface->phc_mode, PHC_READINGS, phc_readings);
+
+  /* Add timeout for the next poll in case no HW timestamp will be captured
+     between the minpoll and maxpoll.  Separate reading of different PHCs to
+     avoid long intervals between handling I/O events. */
+  SCH_RemoveTimeout(iface->poll_timeout_id);
+  interval = UTI_Log2ToDouble(iface->maxpoll);
+  iface->poll_timeout_id = SCH_AddTimeoutInClass(interval, interval /
+                                                   ARR_GetSize(interfaces) / 4, 0.1,
+                                                 SCH_PhcPollClass, poll_timeout, iface);
+
+  if (n_readings <= 0)
+    return;
+
+  if (!HCL_ProcessReadings(iface->clock, n_readings, phc_readings,
+                           &sample_phc_ts, &sample_sys_ts, &phc_err))
+    return;
+
+  LCL_CookTime(&sample_sys_ts, &sample_local_ts, &local_err);
+  HCL_AccumulateSample(iface->clock, &sample_phc_ts, &sample_local_ts, phc_err + local_err);
+
+  update_interface_speed(iface);
+}
+
+/* ================================================== */
+
 static void
 process_hw_timestamp(struct Interface *iface, struct timespec *hw_ts,
                     NTP_Local_Timestamp *local_ts, int rx_ntp_length, int family,
                     int l2_length)
 {
-  struct timespec sample_phc_ts, sample_sys_ts, sample_local_ts, ts;
-  double rx_correction, ts_delay, phc_err, local_err;
+  double rx_correction, ts_delay, local_err;
+  struct timespec ts;

-  if (HCL_NeedsNewSample(iface->clock, &local_ts->ts)) {
-    if (!SYS_Linux_GetPHCSample(iface->phc_fd, iface->phc_nocrossts, iface->precision,
-                                &iface->phc_mode, &sample_phc_ts, &sample_sys_ts,
-                                &phc_err))
-      return;
-
-    LCL_CookTime(&sample_sys_ts, &sample_local_ts, &local_err);
-    HCL_AccumulateSample(iface->clock, &sample_phc_ts, &sample_local_ts,
-                         phc_err + local_err);
-
-    update_interface_speed(iface);
-  }
+  poll_phc(iface, &local_ts->ts);

  /* We need to transpose RX timestamps as hardware timestamps are normally
     preamble timestamps and RX timestamps in NTP are supposed to be trailer
@@ -610,6 +602,28 @@ process_hw_timestamp(struct Interface *iface, struct timespec *hw_ts,
  local_ts->source = NTP_TS_HARDWARE;
 }

+/* ================================================== */
+
+static void
+process_sw_timestamp(struct timespec *sw_ts, NTP_Local_Timestamp *local_ts)
+{
+  double ts_delay, local_err;
+  struct timespec ts;
+
+  LCL_CookTime(sw_ts, &ts, &local_err);
+
+  ts_delay = UTI_DiffTimespecsToDouble(&local_ts->ts, &ts);
+
+  if (fabs(ts_delay) > MAX_TS_DELAY) {
+    DEBUG_LOG("Unacceptable timestamp delay %.9f", ts_delay);
+    return;
+  }
+
+  local_ts->ts = ts;
+  local_ts->err = local_err;
+  local_ts->source = NTP_TS_KERNEL;
+}
+
 /* ================================================== */
 /* Extract UDP data from a layer 2 message.  Supported is Ethernet
   with optional VLAN tags. */
@@ -726,17 +740,11 @@ NIO_Linux_ProcessMessage(SCK_Message *message, NTP_Local_Address *local_addr,
    } else {
      DEBUG_LOG("HW clock not found for interface %d", ts_if_index);
    }
-
-    /* If a HW transmit timestamp was received, resume processing
-       of non-error messages on this socket */
-    if (is_tx)
-      resume_socket(local_addr->sock_fd);
  }

  if (local_ts->source == NTP_TS_DAEMON && !UTI_IsZeroTimespec(&message->timestamp.kernel) &&
      (!is_tx || UTI_IsZeroTimespec(&message->timestamp.hw))) {
-    LCL_CookTime(&message->timestamp.kernel, &local_ts->ts, &local_ts->err);
-    local_ts->source = NTP_TS_KERNEL;
+    process_sw_timestamp(&message->timestamp.kernel, local_ts);
  }

  /* If the kernel is slow with enabling RX timestamping, open a dummy
@@ -757,7 +765,7 @@ NIO_Linux_ProcessMessage(SCK_Message *message, NTP_Local_Address *local_addr,
  l2_length = message->length;
  message->length = extract_udp_data(message->data, &message->remote_addr.ip, message->length);

-  DEBUG_LOG("Extracted message for %s fd=%d len=%u",
+  DEBUG_LOG("Extracted message for %s fd=%d len=%d",
            UTI_IPSockAddrToString(&message->remote_addr.ip),
            local_addr->sock_fd, message->length);

@@ -775,7 +783,10 @@ NIO_Linux_ProcessMessage(SCK_Message *message, NTP_Local_Address *local_addr,
    return 1;
  }

-  if (message->length < NTP_HEADER_LENGTH)
+  if (!NIO_UnwrapMessage(message, local_addr->sock_fd))
+    return 1;
+
+  if (message->length < NTP_HEADER_LENGTH || message->length > sizeof (NTP_Packet))
    return 1;

  NSR_ProcessTx(&message->remote_addr.ip, local_addr, local_ts, message->data, message->length);
@@ -791,23 +802,9 @@ NIO_Linux_RequestTxTimestamp(SCK_Message *message, int sock_fd)
  if (!ts_flags)
    return;

-  /* If a HW transmit timestamp is requested on a client socket, monitor
-     events on the socket in order to avoid processing of a fast response
-     without the HW timestamp of the request */
-  if (ts_tx_flags & SOF_TIMESTAMPING_TX_HARDWARE && !NIO_IsServerSocket(sock_fd))
-    monitored_socket = sock_fd;
-
  /* Check if TX timestamping is disabled on this socket */
  if (permanent_ts_options || !NIO_IsServerSocket(sock_fd))
    return;

  message->timestamp.tx_flags = ts_tx_flags;
 }
-
-/* ================================================== */
-
-void
-NIO_Linux_NotifySocketClosing(int sock_fd)
-{
-  resume_socket(sock_fd);
-}
--- a/ntp_io_linux.h
+++ b/ntp_io_linux.h
@@ -33,15 +33,13 @@ extern void NIO_Linux_Initialise(void);

 extern void NIO_Linux_Finalise(void);

-extern int NIO_Linux_SetTimestampSocketOptions(int sock_fd, int client_only, int *events);
+extern int NIO_Linux_IsHwTsEnabled(void);

-extern int NIO_Linux_ProcessEvent(int sock_fd, int event);
+extern int NIO_Linux_SetTimestampSocketOptions(int sock_fd, int client_only, int *events);

 extern int NIO_Linux_ProcessMessage(SCK_Message *message, NTP_Local_Address *local_addr,
                                    NTP_Local_Timestamp *local_ts, int event);

 extern void NIO_Linux_RequestTxTimestamp(SCK_Message *message, int sock_fd);

-extern void NIO_Linux_NotifySocketClosing(int sock_fd);
-
 #endif
--- a/ntp_signd.c
+++ b/ntp_signd.c
@@ -96,14 +96,6 @@ static unsigned int queue_tail;
 /* Unix domain socket connected to ntp_signd */
 static int sock_fd;

-#define MIN_AUTH_DELAY 1.0e-5
-#define MAX_AUTH_DELAY 1.0e-2
-
-/* Average time needed for signing one packet.  This is used to adjust the
-   transmit timestamp in NTP packets.  The timestamp won't be very accurate as
-   the delay is variable, but it should be good enough for MS-SNTP clients. */
-static double auth_delay;
-
 /* Flag indicating if the MS-SNTP authentication is enabled */
 static int enabled;

@@ -183,10 +175,6 @@ process_response(SignInstance *inst)
  NIO_SendPacket(&inst->response.signed_packet, &inst->remote_addr, &inst->local_addr,
                 ntohl(inst->response.length) + sizeof (inst->response.length) -
                 offsetof(SigndResponse, signed_packet), 0);
-
-  /* Update exponential moving average of the authentication delay */
-  delay = CLAMP(MIN_AUTH_DELAY, delay, MAX_AUTH_DELAY);
-  auth_delay += 0.1 * (delay - auth_delay);
 }

 /* ================================================== */
@@ -274,7 +262,6 @@ void
 NSD_Initialise()
 {
  sock_fd = INVALID_SOCK_FD;
-  auth_delay = MIN_AUTH_DELAY;
  enabled = CNF_GetNtpSigndSocket() && CNF_GetNtpSigndSocket()[0];

  if (!enabled)
@@ -301,13 +288,6 @@ NSD_Finalise()

 /* ================================================== */

-extern int NSD_GetAuthDelay(uint32_t key_id)
-{
-  return 1.0e9 * auth_delay;
-}
-
-/* ================================================== */
-
 int
 NSD_SignAndSendPacket(uint32_t key_id, NTP_Packet *packet, NTP_PacketInfo *info,
                      NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr)
--- a/ntp_signd.h
+++ b/ntp_signd.h
@@ -35,9 +35,6 @@ extern void NSD_Initialise(void);
 /* Finalisation function */
 extern void NSD_Finalise(void);

-/* Function to get an estimate of delay due to signing */
-extern int NSD_GetAuthDelay(uint32_t key_id);
-
 /* Function to sign an NTP packet and send it */
 extern int NSD_SignAndSendPacket(uint32_t key_id, NTP_Packet *packet, NTP_PacketInfo *info,
                                 NTP_Remote_Address *remote_addr, NTP_Local_Address *local_addr);
--- a/ntp_sources.c
+++ b/ntp_sources.c
--- a/ntp_sources.h
+++ b/ntp_sources.h
@@ -50,14 +50,15 @@ typedef enum {
 } NSR_Status;

 /* Procedure to add a new server or peer source. */
-extern NSR_Status NSR_AddSource(NTP_Remote_Address *remote_addr, NTP_Source_Type type, SourceParameters *params);
+extern NSR_Status NSR_AddSource(NTP_Remote_Address *remote_addr, NTP_Source_Type type,
+                                SourceParameters *params, uint32_t *conf_id);

 /* Procedure to add a new server, peer source, or pool of servers specified by
   name instead of address.  The name is resolved in exponentially increasing
   intervals until it succeeds or fails with a non-temporary error.  If the
   name is an address, it is equivalent to NSR_AddSource(). */
 extern NSR_Status NSR_AddSourceByName(char *name, int port, int pool, NTP_Source_Type type,
-                                      SourceParameters *params);
+                                      SourceParameters *params, uint32_t *conf_id);

 /* Function type for handlers to be called back when an attempt
 * (possibly unsuccessful) to resolve unresolved sources ends */
@@ -76,7 +77,10 @@ extern void NSR_StartSources(void);
 extern void NSR_AutoStartSources(void);

 /* Procedure to remove a source */
-extern NSR_Status NSR_RemoveSource(NTP_Remote_Address *remote_addr);
+extern NSR_Status NSR_RemoveSource(IPAddr *address);
+
+/* Procedure to remove all sources matching a configuration ID */
+extern void NSR_RemoveSourcesById(uint32_t conf_id);

 /* Procedure to remove all sources */
 extern void NSR_RemoveAllSources(void);
@@ -87,15 +91,16 @@ extern void NSR_HandleBadSource(IPAddr *address);
 /* Procedure to resolve all names again */
 extern void NSR_RefreshAddresses(void);

-/* Procedure to update the address of a source */
+/* Procedure to update the address of a source.  The update may be
+   postponed. */
 extern NSR_Status NSR_UpdateSourceNtpAddress(NTP_Remote_Address *old_addr,
                                             NTP_Remote_Address *new_addr);

 /* Procedure to get local reference ID corresponding to a source */
 extern uint32_t NSR_GetLocalRefid(IPAddr *address);

-/* Procedure to get the name of a source.  If the source doesn't have a name,
-   it returns a temporary string containing formatted address. */
+/* Procedure to get the name of a source as it was specified (it may be
+   an IP address) */
 extern char *NSR_GetName(IPAddr *address);

 /* This routine is called by ntp_io when a new packet arrives off the network */
@@ -136,8 +141,12 @@ extern int NSR_InitiateSampleBurst(int n_good_samples, int n_total_samples, IPAd

 extern void NSR_ReportSource(RPT_SourceReport *report, struct timespec *now);

+extern int NSR_GetAuthReport(IPAddr *address, RPT_AuthReport *report);
+
 extern int NSR_GetNTPReport(RPT_NTPReport *report);

 extern void NSR_GetActivityReport(RPT_ActivityReport *report);

+extern void NSR_DumpAuthData(void);
+
 #endif /* GOT_NTP_SOURCES_H */
--- a/nts_ke.h
+++ b/nts_ke.h
@@ -29,6 +29,8 @@

 #include "siv.h"

+#define NKE_PORT                        4460
+
 #define NKE_RECORD_CRITICAL_BIT         (1U << 15)
 #define NKE_RECORD_END_OF_MESSAGE       0
 #define NKE_RECORD_NEXT_PROTOCOL        1
@@ -46,7 +48,7 @@
 #define NKE_ERROR_INTERNAL_SERVER_ERROR 2

 #define NKE_ALPN_NAME                   "ntske/1"
-#define NKE_EXPORTER_LABEL              "EXPORTER-network-time-security/1"
+#define NKE_EXPORTER_LABEL              "EXPORTER-network-time-security"
 #define NKE_EXPORTER_CONTEXT_C2S        "\x0\x0\x0\xf\x0"
 #define NKE_EXPORTER_CONTEXT_S2C        "\x0\x0\x0\xf\x1"

@@ -56,11 +58,21 @@
 #define NKE_MAX_COOKIES                 8
 #define NKE_MAX_KEY_LENGTH SIV_MAX_KEY_LENGTH

+#define NKE_RETRY_FACTOR2_CONNECT       4
+#define NKE_RETRY_FACTOR2_TLS           10
+#define NKE_MAX_RETRY_INTERVAL2         19
+
 typedef struct {
  int length;
  unsigned char key[NKE_MAX_KEY_LENGTH];
 } NKE_Key;

+typedef struct {
+  SIV_Algorithm algorithm;
+  NKE_Key c2s;
+  NKE_Key s2c;
+} NKE_Context;
+
 typedef struct {
  int length;
  unsigned char cookie[NKE_MAX_COOKIE_LENGTH];
--- a/nts_ke_client.c
+++ b/nts_ke_client.c
@@ -2,7 +2,7 @@
  chronyd/chronyc - Programs for keeping computer clocks accurate.

 **********************************************************************
- * Copyright (C) Miroslav Lichvar  2020
+ * Copyright (C) Miroslav Lichvar  2020-2021
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
@@ -44,22 +44,23 @@
 struct NKC_Instance_Record {
  char *name;
  IPSockAddr address;
+  NKSN_Credentials credentials;
  NKSN_Instance session;
  int destroying;
  int got_response;
  int resolving_name;

-  SIV_Algorithm siv_algorithm;
-  NKE_Key c2s, s2c;
+  NKE_Context context;
  NKE_Cookie cookies[NKE_MAX_COOKIES];
  int num_cookies;
-  char server_name[NKE_MAX_RECORD_BODY_LENGTH + 1];
+  char server_name[NKE_MAX_RECORD_BODY_LENGTH + 2];
  IPSockAddr ntp_address;
 };

 /* ================================================== */

-static void *client_credentials;
+static NKSN_Credentials default_credentials = NULL;
+static int default_credentials_refs = 0;

 /* ================================================== */

@@ -72,7 +73,7 @@ name_resolve_handler(DNS_Status status, int n_addrs, IPAddr *ip_addrs, void *arg
  inst->resolving_name = 0;

  if (inst->destroying) {
-    NKC_DestroyInstance(inst);
+    Free(inst);
    return;
  }

@@ -85,7 +86,7 @@ name_resolve_handler(DNS_Status status, int n_addrs, IPAddr *ip_addrs, void *arg

  inst->ntp_address.ip_addr = ip_addrs[0];

-  /* Prefer an address of the same family as NTS-KE */
+  /* Prefer an address in the same family as the NTS-KE server */
  for (i = 0; i < n_addrs; i++) {
    DEBUG_LOG("%s resolved to %s", inst->server_name, UTI_IPToString(&ip_addrs[i]));
    if (ip_addrs[i].family == inst->address.ip_addr.family) {
@@ -101,16 +102,22 @@ static int
 prepare_request(NKC_Instance inst)
 {
  NKSN_Instance session = inst->session;
-  uint16_t datum;
+  uint16_t data[2];
+  int length;

  NKSN_BeginMessage(session);

-  datum = htons(NKE_NEXT_PROTOCOL_NTPV4);
-  if (!NKSN_AddRecord(session, 1, NKE_RECORD_NEXT_PROTOCOL, &datum, sizeof (datum)))
+  data[0] = htons(NKE_NEXT_PROTOCOL_NTPV4);
+  if (!NKSN_AddRecord(session, 1, NKE_RECORD_NEXT_PROTOCOL, data, sizeof (data[0])))
    return 0;

-  datum = htons(AEAD_AES_SIV_CMAC_256);
-  if (!NKSN_AddRecord(session, 1, NKE_RECORD_AEAD_ALGORITHM, &datum, sizeof (datum)))
+  length = 0;
+  if (SIV_GetKeyLength(AEAD_AES_128_GCM_SIV) > 0)
+    data[length++] = htons(AEAD_AES_128_GCM_SIV);
+  if (SIV_GetKeyLength(AEAD_AES_SIV_CMAC_256) > 0)
+    data[length++] = htons(AEAD_AES_SIV_CMAC_256);
+  if (!NKSN_AddRecord(session, 1, NKE_RECORD_AEAD_ALGORITHM, data,
+                      length * sizeof (data[0])))
    return 0;

  if (!NKSN_EndMessage(session))
@@ -126,9 +133,10 @@ process_response(NKC_Instance inst)
 {
  int next_protocol = -1, aead_algorithm = -1, error = 0;
  int i, critical, type, length;
-  uint16_t data[NKE_MAX_COOKIE_LENGTH / sizeof (uint16_t)];
+  uint16_t data[NKE_MAX_RECORD_BODY_LENGTH / sizeof (uint16_t)];

-  assert(NKE_MAX_COOKIE_LENGTH % sizeof (uint16_t) == 0);
+  assert(NKE_MAX_COOKIE_LENGTH <= NKE_MAX_RECORD_BODY_LENGTH);
+  assert(sizeof (data) % sizeof (uint16_t) == 0);
  assert(sizeof (uint16_t) == 2);

  inst->num_cookies = 0;
@@ -140,6 +148,13 @@ process_response(NKC_Instance inst)
    if (!NKSN_GetRecord(inst->session, &critical, &type, &length, &data, sizeof (data)))
      break;

+    if (length > sizeof (data)) {
+      DEBUG_LOG("Record too long type=%d length=%d critical=%d", type, length, critical);
+      if (critical)
+        error = 1;
+      continue;
+    }
+
    switch (type) {
      case NKE_RECORD_NEXT_PROTOCOL:
        if (!critical || length != 2 || ntohs(data[0]) != NKE_NEXT_PROTOCOL_NTPV4) {
@@ -150,13 +165,15 @@ process_response(NKC_Instance inst)
        next_protocol = NKE_NEXT_PROTOCOL_NTPV4;
        break;
      case NKE_RECORD_AEAD_ALGORITHM:
-        if (length != 2 || ntohs(data[0]) != AEAD_AES_SIV_CMAC_256) {
+        if (length != 2 || (ntohs(data[0]) != AEAD_AES_SIV_CMAC_256 &&
+                            ntohs(data[0]) != AEAD_AES_128_GCM_SIV) ||
+            SIV_GetKeyLength(ntohs(data[0])) <= 0) {
          DEBUG_LOG("Unexpected NTS-KE AEAD algorithm");
          error = 1;
          break;
        }
-        aead_algorithm = AEAD_AES_SIV_CMAC_256;
-        inst->siv_algorithm = aead_algorithm;
+        aead_algorithm = ntohs(data[0]);
+        inst->context.algorithm = aead_algorithm;
        break;
      case NKE_RECORD_ERROR:
        if (length == 2)
@@ -169,13 +186,21 @@ process_response(NKC_Instance inst)
        error = 1;
        break;
      case NKE_RECORD_COOKIE:
-        DEBUG_LOG("Got cookie #%d length=%d", inst->num_cookies + 1, length);
-        assert(NKE_MAX_COOKIE_LENGTH == sizeof (inst->cookies[inst->num_cookies].cookie));
-        if (length <= NKE_MAX_COOKIE_LENGTH && inst->num_cookies < NKE_MAX_COOKIES) {
-          inst->cookies[inst->num_cookies].length = length;
-          memcpy(inst->cookies[inst->num_cookies].cookie, data, length);
-          inst->num_cookies++;
+        DEBUG_LOG("Got cookie length=%d", length);
+
+        if (length < 1 || length > NKE_MAX_COOKIE_LENGTH || length % 4 != 0 ||
+            inst->num_cookies >= NKE_MAX_COOKIES) {
+          DEBUG_LOG("Unexpected length/cookie");
+          break;
        }
+
+        assert(NKE_MAX_COOKIE_LENGTH == sizeof (inst->cookies[inst->num_cookies].cookie));
+        assert(NKE_MAX_COOKIES == sizeof (inst->cookies) /
+                                  sizeof (inst->cookies[inst->num_cookies]));
+        inst->cookies[inst->num_cookies].length = length;
+        memcpy(inst->cookies[inst->num_cookies].cookie, data, length);
+
+        inst->num_cookies++;
        break;
      case NKE_RECORD_NTPV4_SERVER_NEGOTIATION:
        if (length < 1 || length >= sizeof (inst->server_name)) {
@@ -188,7 +213,7 @@ process_response(NKC_Instance inst)
        inst->server_name[length] = '\0';

        /* Make sure the name is printable and has no spaces */
-        for (i = 0; i < length && isgraph(inst->server_name[i]); i++)
+        for (i = 0; i < length && isgraph((unsigned char)inst->server_name[i]); i++)
          ;
        if (i != length) {
          DEBUG_LOG("Invalid server name");
@@ -219,7 +244,7 @@ process_response(NKC_Instance inst)

  if (error || inst->num_cookies == 0 ||
      next_protocol != NKE_NEXT_PROTOCOL_NTPV4 ||
-      aead_algorithm != AEAD_AES_SIV_CMAC_256)
+      aead_algorithm < 0)
    return 0;

  return 1;
@@ -237,13 +262,25 @@ handle_message(void *arg)
    return 0;
  }

-  if (!NKSN_GetKeys(inst->session, inst->siv_algorithm, &inst->c2s, &inst->s2c))
+  if (!NKSN_GetKeys(inst->session, inst->context.algorithm,
+                    &inst->context.c2s, &inst->context.s2c))
    return 0;

  if (inst->server_name[0] != '\0') {
    if (inst->resolving_name)
      return 0;
    if (!UTI_StringToIP(inst->server_name, &inst->ntp_address.ip_addr)) {
+      int length = strlen(inst->server_name);
+
+      /* Add a trailing dot if not present to force the name to be
+         resolved as a fully qualified domain name */
+      if (length < 1 || length + 1 >= sizeof (inst->server_name))
+        return 0;
+      if (inst->server_name[length - 1] != '.') {
+        inst->server_name[length] = '.';
+        inst->server_name[length + 1] = '\0';
+      }
+
      DNS_Name2IPAddressAsync(inst->server_name, name_resolve_handler, inst);
      inst->resolving_name = 1;
    }
@@ -256,27 +293,13 @@ handle_message(void *arg)

 /* ================================================== */

-void
-NKC_Initialise(void)
-{
-  client_credentials = NULL;
-}
-
-/* ================================================== */
-
-void
-NKC_Finalise(void)
-{
-  if (client_credentials)
-    NKSN_DestroyCertCredentials(client_credentials);
-}
-
-/* ================================================== */
-
 NKC_Instance
-NKC_CreateInstance(IPSockAddr *address, const char *name)
+NKC_CreateInstance(IPSockAddr *address, const char *name, uint32_t cert_set)
 {
+  const char **trusted_certs;
+  uint32_t *certs_ids;
  NKC_Instance inst;
+  int n_certs;

  inst = MallocNew(struct NKC_Instance_Record);

@@ -287,10 +310,21 @@ NKC_CreateInstance(IPSockAddr *address, const char *name)
  inst->destroying = 0;
  inst->got_response = 0;

-  /* Create the credentials with the first client instance and share them
-     with other instances */
-  if (!client_credentials)
-    client_credentials = NKSN_CreateCertCredentials(NULL, NULL, CNF_GetNtsTrustedCertFile());
+  n_certs = CNF_GetNtsTrustedCertsPaths(&trusted_certs, &certs_ids);
+
+  /* Share the credentials among clients using the default set of trusted
+     certificates, which likely contains most certificates */
+  if (cert_set == 0) {
+    if (!default_credentials)
+      default_credentials = NKSN_CreateClientCertCredentials(trusted_certs, certs_ids,
+                                                             n_certs, cert_set);
+    inst->credentials = default_credentials;
+    if (default_credentials)
+      default_credentials_refs++;
+  } else {
+    inst->credentials = NKSN_CreateClientCertCredentials(trusted_certs, certs_ids,
+                                                         n_certs, cert_set);
+  }

  return inst;
 }
@@ -300,15 +334,29 @@ NKC_CreateInstance(IPSockAddr *address, const char *name)
 void
 NKC_DestroyInstance(NKC_Instance inst)
 {
-  /* If the resolver is running, destroy the instance later when finished */
+  NKSN_DestroyInstance(inst->session);
+
+  Free(inst->name);
+
+  if (inst->credentials) {
+    if (inst->credentials == default_credentials) {
+      default_credentials_refs--;
+      if (default_credentials_refs <= 0) {
+        NKSN_DestroyCertCredentials(default_credentials);
+        default_credentials = NULL;
+      }
+    } else {
+      NKSN_DestroyCertCredentials(inst->credentials);
+    }
+  }
+
+  /* If the asynchronous resolver is running, let the handler free
+     the instance later */
  if (inst->resolving_name) {
    inst->destroying = 1;
    return;
  }

-  NKSN_DestroyInstance(inst->session);
-
-  Free(inst->name);
  Free(inst);
 }

@@ -318,28 +366,43 @@ int
 NKC_Start(NKC_Instance inst)
 {
  IPSockAddr local_addr;
+  char label[512], *iface;
  int sock_fd;

  assert(!NKC_IsActive(inst));

-  if (!client_credentials) {
+  inst->got_response = 0;
+
+  if (!inst->credentials) {
    DEBUG_LOG("Missing client credentials");
    return 0;
  }

-  /* Follow the bindacqaddress setting */
-  CNF_GetBindAcquisitionAddress(inst->address.ip_addr.family, &local_addr.ip_addr);
-  if (local_addr.ip_addr.family != inst->address.ip_addr.family)
-    SCK_GetAnyLocalIPAddress(inst->address.ip_addr.family, &local_addr.ip_addr);
-
-  local_addr.port = 0;
-
-  sock_fd = SCK_OpenTcpSocket(&inst->address, &local_addr, 0);
-  if (sock_fd < 0)
+  /* Don't try to connect if missing the algorithm which all servers
+     are required to support */
+  if (SIV_GetKeyLength(AEAD_AES_SIV_CMAC_256) <= 0) {
+    LOG(LOGS_ERR, "Missing AES-SIV-CMAC-256");
    return 0;
+  }

-  /* Start a NTS-KE session */
-  if (!NKSN_StartSession(inst->session, sock_fd, client_credentials, CLIENT_TIMEOUT)) {
+  /* Follow the bindacqaddress and bindacqdevice settings */
+  CNF_GetBindAcquisitionAddress(inst->address.ip_addr.family, &local_addr.ip_addr);
+  local_addr.port = 0;
+  iface = CNF_GetBindAcquisitionInterface();
+
+  /* Make a label containing both the address and name of the server */
+  if (snprintf(label, sizeof (label), "%s (%s)",
+               UTI_IPSockAddrToString(&inst->address), inst->name) >= sizeof (label))
+    ;
+
+  sock_fd = SCK_OpenTcpSocket(&inst->address, &local_addr, iface, 0);
+  if (sock_fd < 0) {
+    LOG(LOGS_ERR, "Could not connect to %s", label);
+    return 0;
+  }
+
+  /* Start an NTS-KE session */
+  if (!NKSN_StartSession(inst->session, sock_fd, label, inst->credentials, CLIENT_TIMEOUT)) {
    SCK_CloseSocket(sock_fd);
    return 0;
  }
@@ -365,8 +428,7 @@ NKC_IsActive(NKC_Instance inst)
 /* ================================================== */

 int
-NKC_GetNtsData(NKC_Instance inst,
-               SIV_Algorithm *siv_algorithm, NKE_Key *c2s, NKE_Key *s2c,
+NKC_GetNtsData(NKC_Instance inst, NKE_Context *context,
               NKE_Cookie *cookies, int *num_cookies, int max_cookies,
               IPSockAddr *ntp_address)
 {
@@ -375,9 +437,7 @@ NKC_GetNtsData(NKC_Instance inst,
  if (!inst->got_response || inst->resolving_name)
    return 0;

-  *siv_algorithm = inst->siv_algorithm;
-  *c2s = inst->c2s;
-  *s2c = inst->s2c;
+  *context = inst->context;

  for (i = 0; i < inst->num_cookies && i < max_cookies; i++)
    cookies[i] = inst->cookies[i];
@@ -385,5 +445,13 @@ NKC_GetNtsData(NKC_Instance inst,

  *ntp_address = inst->ntp_address;

-  return i;
+  return 1;
+}
+
+/* ================================================== */
+
+int
+NKC_GetRetryFactor(NKC_Instance inst)
+{
+  return NKSN_GetRetryFactor(inst->session);
 }
--- a/nts_ke_client.h
+++ b/nts_ke_client.h
@@ -32,12 +32,8 @@

 typedef struct NKC_Instance_Record *NKC_Instance;

-/* Init and fini functions */
-extern void NKC_Initialise(void);
-extern void NKC_Finalise(void);
-
 /* Create a client NTS-KE instance */
-extern NKC_Instance NKC_CreateInstance(IPSockAddr *address, const char *name);
+extern NKC_Instance NKC_CreateInstance(IPSockAddr *address, const char *name, uint32_t cert_set);

 /* Destroy an instance */
 extern void NKC_DestroyInstance(NKC_Instance inst);
@@ -50,9 +46,11 @@ extern int NKC_Start(NKC_Instance inst);
 extern int NKC_IsActive(NKC_Instance inst);

 /* Get the NTS data if the session was successful */
-extern int NKC_GetNtsData(NKC_Instance inst,
-                          SIV_Algorithm *siv_algorithm, NKE_Key *c2s, NKE_Key *s2c,
+extern int NKC_GetNtsData(NKC_Instance inst, NKE_Context *context,
                          NKE_Cookie *cookies, int *num_cookies, int max_cookies,
                          IPSockAddr *ntp_address);

+/* Get a factor to calculate retry interval (in log2 seconds) */
+extern int NKC_GetRetryFactor(NKC_Instance inst);
+
 #endif
--- a/nts_ke_server.c
+++ b/nts_ke_server.c
--- a/nts_ke_server.h
+++ b/nts_ke_server.h
@@ -30,13 +30,20 @@
 #include "nts_ke.h"

 /* Init and fini functions */
-extern void NKS_Initialise(int scfilter_level);
+extern void NKS_PreInitialise(uid_t uid, gid_t gid, int scfilter_level);
+extern void NKS_Initialise(void);
 extern void NKS_Finalise(void);

-/* Generate a new NTS cookie containing the C2S and S2C keys */
-extern int NKS_GenerateCookie(NKE_Key *c2s, NKE_Key *s2c, NKE_Cookie *cookie);
+/* Save the current server keys */
+extern void NKS_DumpKeys(void);

-/* Validate a cookie and extract the C2S and S2C keys */
-extern int NKS_DecodeCookie(NKE_Cookie *cookie, NKE_Key *c2s, NKE_Key *s2c);
+/* Reload the keys */
+extern void NKS_ReloadKeys(void);
+
+/* Generate an NTS cookie with a given context */
+extern int NKS_GenerateCookie(NKE_Context *context, NKE_Cookie *cookie);
+
+/* Validate a cookie and decode the context */
+extern int NKS_DecodeCookie(NKE_Cookie *cookie, NKE_Context *context);

 #endif
--- a/nts_ke_session.c
+++ b/nts_ke_session.c
@@ -2,7 +2,7 @@
  chronyd/chronyc - Programs for keeping computer clocks accurate.

 **********************************************************************
- * Copyright (C) Miroslav Lichvar  2020
+ * Copyright (C) Miroslav Lichvar  2020-2021
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
@@ -31,6 +31,7 @@
 #include "nts_ke_session.h"

 #include "conf.h"
+#include "local.h"
 #include "logging.h"
 #include "memory.h"
 #include "siv.h"
@@ -39,6 +40,7 @@
 #include "util.h"

 #include <gnutls/gnutls.h>
+#include <gnutls/x509.h>

 #define INVALID_SOCK_FD (-8)

@@ -66,18 +68,19 @@ typedef enum {

 struct NKSN_Instance_Record {
  int server;
-  char *name;
+  char *server_name;
  NKSN_MessageHandler handler;
  void *handler_arg;

  KeState state;
  int sock_fd;
+  char *label;
  gnutls_session_t tls_session;
  SCH_TimeoutID timeout_id;
+  int retry_factor;

  struct Message message;
  int new_message;
-  int ended_message;
 };

 /* ================================================== */
@@ -86,6 +89,8 @@ static gnutls_priority_t priority_cache;

 static int credentials_counter = 0;

+static int clock_updates = 0;
+
 /* ================================================== */

 static void
@@ -104,6 +109,8 @@ add_record(struct Message *message, int critical, int type, const void *body, in
 {
  struct RecordHeader header;

+  assert(message->length <= sizeof (message->data));
+
  if (body_length < 0 || body_length > 0xffff || type < 0 || type > 0x7fff ||
      message->length + sizeof (header) + body_length > sizeof (message->data))
    return 0;
@@ -147,6 +154,7 @@ get_record(struct Message *message, int *critical, int *type, int *body_length,

  blen = ntohs(header.body_length);
  rlen = sizeof (header) + blen;
+  assert(blen >= 0 && rlen > 0);

  if (message->length < message->parsed + rlen)
    return 0;
@@ -206,19 +214,33 @@ create_tls_session(int server_mode, int sock_fd, const char *server_name,
  unsigned char alpn_name[sizeof (NKE_ALPN_NAME)];
  gnutls_session_t session;
  gnutls_datum_t alpn;
+  unsigned int flags;
  int r;

-  r = gnutls_init(&session, GNUTLS_NONBLOCK | (server_mode ? GNUTLS_SERVER : GNUTLS_CLIENT));
+  r = gnutls_init(&session, GNUTLS_NONBLOCK | GNUTLS_NO_TICKETS |
+                  (server_mode ? GNUTLS_SERVER : GNUTLS_CLIENT));
  if (r < 0) {
    LOG(LOGS_ERR, "Could not %s TLS session : %s", "create", gnutls_strerror(r));
    return NULL;
  }

  if (!server_mode) {
-    r = gnutls_server_name_set(session, GNUTLS_NAME_DNS, server_name, strlen(server_name));
-    if (r < 0)
-      goto error;
-    gnutls_session_set_verify_cert(session, server_name, 0);
+    assert(server_name);
+
+    if (!UTI_IsStringIP(server_name)) {
+      r = gnutls_server_name_set(session, GNUTLS_NAME_DNS, server_name, strlen(server_name));
+      if (r < 0)
+        goto error;
+    }
+
+    flags = 0;
+
+    if (clock_updates < CNF_GetNoCertTimeCheck()) {
+      flags |= GNUTLS_VERIFY_DISABLE_TIME_CHECKS | GNUTLS_VERIFY_DISABLE_TRUSTED_TIME_CHECKS;
+      DEBUG_LOG("Disabled time checks");
+    }
+
+    gnutls_session_set_verify_cert(session, server_name, flags);
  }

  r = gnutls_priority_set(session, priority);
@@ -261,6 +283,9 @@ stop_session(NKSN_Instance inst)
  SCK_CloseSocket(inst->sock_fd);
  inst->sock_fd = INVALID_SOCK_FD;

+  Free(inst->label);
+  inst->label = NULL;
+
  gnutls_deinit(inst->tls_session);
  inst->tls_session = NULL;

@@ -275,7 +300,7 @@ session_timeout(void *arg)
 {
  NKSN_Instance inst = arg;

-  LOG(inst->server ? LOGS_DEBUG : LOGS_ERR, "NTS-KE session with %s timed out", inst->name);
+  LOG(inst->server ? LOGS_DEBUG : LOGS_ERR, "NTS-KE session with %s timed out", inst->label);

  inst->timeout_id = 0;
  stop_session(inst);
@@ -284,33 +309,25 @@ session_timeout(void *arg)
 /* ================================================== */

 static int
-get_socket_error(int sock_fd)
+check_alpn(NKSN_Instance inst)
 {
-  int optval;
-  socklen_t optlen = sizeof (optval);
+  gnutls_datum_t alpn;

-  if (getsockopt(sock_fd, SOL_SOCKET, SO_ERROR, &optval, &optlen) < 0) {
-    DEBUG_LOG("getsockopt() failed : %s", strerror(errno));
-    return EINVAL;
-  }
+  if (gnutls_alpn_get_selected_protocol(inst->tls_session, &alpn) < 0 ||
+      alpn.size != sizeof (NKE_ALPN_NAME) - 1 ||
+      memcmp(alpn.data, NKE_ALPN_NAME, sizeof (NKE_ALPN_NAME) - 1) != 0)
+    return 0;

-  return optval;
+  return 1;
 }

 /* ================================================== */

-static int
-check_alpn(NKSN_Instance inst)
+static void
+set_input_output(NKSN_Instance inst, int output)
 {
-  gnutls_datum_t alpn;
-  int r;
-
-  r = gnutls_alpn_get_selected_protocol(inst->tls_session, &alpn);
-  if (r < 0 || alpn.size != sizeof (NKE_ALPN_NAME) - 1 ||
-      strncmp((const char *)alpn.data, NKE_ALPN_NAME, sizeof (NKE_ALPN_NAME) - 1))
-    return 0;
-
-  return 1;
+  SCH_SetFileHandlerEvent(inst->sock_fd, SCH_FILE_INPUT, !output);
+  SCH_SetFileHandlerEvent(inst->sock_fd, SCH_FILE_OUTPUT, output);
 }

 /* ================================================== */
@@ -336,7 +353,7 @@ change_state(NKSN_Instance inst, KeState state)
      assert(0);
  }

-  SCH_SetFileHandlerEvent(inst->sock_fd, SCH_FILE_OUTPUT, output);
+  set_input_output(inst, output);

  inst->state = state;
 }
@@ -357,15 +374,17 @@ handle_event(NKSN_Instance inst, int event)
      if (event != SCH_FILE_OUTPUT)
        return 0;

-      r = get_socket_error(inst->sock_fd);
+      /* Get the socket error */
+      if (!SCK_GetIntOption(inst->sock_fd, SOL_SOCKET, SO_ERROR, &r))
+        r = EINVAL;

-      if (r) {
-        LOG(LOGS_ERR, "Could not connect to %s : %s", inst->name, strerror(r));
+      if (r != 0) {
+        LOG(LOGS_ERR, "Could not connect to %s : %s", inst->label, strerror(r));
        stop_session(inst);
        return 0;
      }

-      DEBUG_LOG("Connected to %s", inst->name);
+      DEBUG_LOG("Connected to %s", inst->label);

      change_state(inst, KE_HANDSHAKE);
      return 0;
@@ -375,27 +394,48 @@ handle_event(NKSN_Instance inst, int event)

      if (r < 0) {
        if (gnutls_error_is_fatal(r)) {
+          gnutls_datum_t cert_error;
+
+          /* Get a description of verification errors */
+          if (r != GNUTLS_E_CERTIFICATE_VERIFICATION_ERROR ||
+              gnutls_certificate_verification_status_print(
+                          gnutls_session_get_verify_cert_status(inst->tls_session),
+                          gnutls_certificate_type_get(inst->tls_session), &cert_error, 0) < 0)
+            cert_error.data = NULL;
+
          LOG(inst->server ? LOGS_DEBUG : LOGS_ERR,
-              "TLS handshake with %s failed : %s", inst->name, gnutls_strerror(r));
+              "TLS handshake with %s failed : %s%s%s", inst->label, gnutls_strerror(r),
+              cert_error.data ? " " : "", cert_error.data ? (const char *)cert_error.data : "");
+
+          if (cert_error.data)
+            gnutls_free(cert_error.data);
+
          stop_session(inst);
+
+          /* Increase the retry interval if the handshake did not fail due
+             to the other end closing the connection */
+          if (r != GNUTLS_E_PULL_ERROR && r != GNUTLS_E_PREMATURE_TERMINATION)
+            inst->retry_factor = NKE_RETRY_FACTOR2_TLS;
+
          return 0;
        }

        /* Disable output when the handshake is trying to receive data */
-        SCH_SetFileHandlerEvent(inst->sock_fd, SCH_FILE_OUTPUT,
-                                gnutls_record_get_direction(inst->tls_session));
+        set_input_output(inst, gnutls_record_get_direction(inst->tls_session));
        return 0;
      }

+      inst->retry_factor = NKE_RETRY_FACTOR2_TLS;
+
      if (DEBUG) {
        char *description = gnutls_session_get_desc(inst->tls_session);
        DEBUG_LOG("Handshake with %s completed %s",
-                  inst->name, description ? description : "");
+                  inst->label, description ? description : "");
        gnutls_free(description);
      }

      if (!check_alpn(inst)) {
-        LOG(inst->server ? LOGS_DEBUG : LOGS_ERR, "NTS-KE not supported by %s", inst->name);
+        LOG(inst->server ? LOGS_DEBUG : LOGS_ERR, "NTS-KE not supported by %s", inst->label);
        stop_session(inst);
        return 0;
      }
@@ -406,6 +446,7 @@ handle_event(NKSN_Instance inst, int event)

    case KE_SEND:
      assert(inst->new_message && message->complete);
+      assert(message->length <= sizeof (message->data) && message->length > message->sent);

      r = gnutls_record_send(inst->tls_session, &message->data[message->sent],
                             message->length - message->sent);
@@ -413,13 +454,13 @@ handle_event(NKSN_Instance inst, int event)
      if (r < 0) {
        if (gnutls_error_is_fatal(r)) {
          LOG(inst->server ? LOGS_DEBUG : LOGS_ERR,
-              "Could not send NTS-KE message to %s : %s", inst->name, gnutls_strerror(r));
+              "Could not send NTS-KE message to %s : %s", inst->label, gnutls_strerror(r));
          stop_session(inst);
        }
        return 0;
      }

-      DEBUG_LOG("Sent %d bytes to %s", r, inst->name);
+      DEBUG_LOG("Sent %d bytes to %s", r, inst->label);

      message->sent += r;
      if (message->sent < message->length)
@@ -448,13 +489,13 @@ handle_event(NKSN_Instance inst, int event)
          if (gnutls_error_is_fatal(r) || r == GNUTLS_E_REHANDSHAKE) {
            LOG(inst->server ? LOGS_DEBUG : LOGS_ERR,
                "Could not receive NTS-KE message from %s : %s",
-                inst->name, gnutls_strerror(r));
+                inst->label, gnutls_strerror(r));
            stop_session(inst);
          }
          return 0;
        }

-        DEBUG_LOG("Received %d bytes from %s", r, inst->name);
+        DEBUG_LOG("Received %d bytes from %s", r, inst->label);

        message->length += r;

@@ -462,7 +503,7 @@ handle_event(NKSN_Instance inst, int event)

      if (!check_message_format(message, r == 0)) {
        LOG(inst->server ? LOGS_DEBUG : LOGS_ERR,
-            "Received invalid NTS-KE message from %s", inst->name);
+            "Received invalid NTS-KE message from %s", inst->label);
        stop_session(inst);
        return 0;
      }
@@ -473,21 +514,22 @@ handle_event(NKSN_Instance inst, int event)

      /* Server will send a response to the client */
      change_state(inst, inst->server ? KE_SEND : KE_SHUTDOWN);
-      break;
+
+      /* Return success to process the received message */
+      return 1;

    case KE_SHUTDOWN:
      r = gnutls_bye(inst->tls_session, GNUTLS_SHUT_RDWR);

      if (r < 0) {
        if (gnutls_error_is_fatal(r)) {
-          DEBUG_LOG("Shutdown with %s failed : %s", inst->name, gnutls_strerror(r));
+          DEBUG_LOG("Shutdown with %s failed : %s", inst->label, gnutls_strerror(r));
          stop_session(inst);
          return 0;
        }

        /* Disable output when the TLS shutdown is trying to receive data */
-        SCH_SetFileHandlerEvent(inst->sock_fd, SCH_FILE_OUTPUT,
-                                gnutls_record_get_direction(inst->tls_session));
+        set_input_output(inst, gnutls_record_get_direction(inst->tls_session));
        return 0;
      }

@@ -499,9 +541,8 @@ handle_event(NKSN_Instance inst, int event)

    default:
      assert(0);
+      return 0;
  }
-
-  return 1;
 }

 /* ================================================== */
@@ -514,6 +555,9 @@ read_write_socket(int fd, int event, void *arg)
  if (!handle_event(inst, event))
    return;

+  /* A valid message was received.  Call the handler to process the message,
+     and prepare a response if it is a server. */
+
  reset_message_parsing(&inst->message);

  if (!(inst->handler)(inst->handler_arg)) {
@@ -524,27 +568,65 @@ read_write_socket(int fd, int event, void *arg)

 /* ================================================== */

-static int gnutls_initialised = 0;
+static time_t
+get_time(time_t *t)
+{
+  struct timespec now;
+
+  LCL_ReadCookedTime(&now, NULL);
+  if (t)
+    *t = now.tv_sec;
+
+  return now.tv_sec;
+}
+
+/* ================================================== */

 static void
+handle_step(struct timespec *raw, struct timespec *cooked, double dfreq,
+            double doffset, LCL_ChangeType change_type, void *anything)
+{
+  if (change_type != LCL_ChangeUnknownStep && clock_updates < INT_MAX)
+    clock_updates++;
+}
+
+/* ================================================== */
+
+static int gnutls_initialised = 0;
+
+static int
 init_gnutls(void)
 {
  int r;

  if (gnutls_initialised)
-    return;
+    return 1;

  r = gnutls_global_init();
  if (r < 0)
    LOG_FATAL("Could not initialise %s : %s", "gnutls", gnutls_strerror(r));

-  /* NTS specification requires TLS1.2 or later */
-  r = gnutls_priority_init2(&priority_cache, "-VERS-SSL3.0:-VERS-TLS1.0:-VERS-TLS1.1",
+  /* Prepare a priority cache for server and client NTS-KE sessions
+     (the NTS specification requires TLS1.3 or later) */
+  r = gnutls_priority_init2(&priority_cache,
+                            "-VERS-SSL3.0:-VERS-TLS1.0:-VERS-TLS1.1:-VERS-TLS1.2:-VERS-DTLS-ALL",
                            NULL, GNUTLS_PRIORITY_INIT_DEF_APPEND);
-  if (r < 0)
-    LOG_FATAL("Could not initialise %s : %s", "priority cache", gnutls_strerror(r));
+  if (r < 0) {
+    LOG(LOGS_ERR, "Could not initialise %s : %s",
+        "priority cache for TLS", gnutls_strerror(r));
+    gnutls_global_deinit();
+    return 0;
+  }
+
+  /* Use our clock instead of the system clock in certificate verification */
+  gnutls_global_set_time_function(get_time);

  gnutls_initialised = 1;
+  DEBUG_LOG("Initialised");
+
+  LCL_AddParameterChangeHandler(handle_step, NULL);
+
+  return 1;
 }

 /* ================================================== */
@@ -552,75 +634,120 @@ init_gnutls(void)
 static void
 deinit_gnutls(void)
 {
-  assert(gnutls_initialised);
+  if (!gnutls_initialised || credentials_counter > 0)
+    return;
+
+  LCL_RemoveParameterChangeHandler(handle_step, NULL);

  gnutls_priority_deinit(priority_cache);
  gnutls_global_deinit();
  gnutls_initialised = 0;
+  DEBUG_LOG("Deinitialised");
 }

 /* ================================================== */

-void *
-NKSN_CreateCertCredentials(char *cert, char *key, char *trusted_certs)
+static NKSN_Credentials
+create_credentials(const char **certs, const char **keys, int n_certs_keys,
+                   const char **trusted_certs, uint32_t *trusted_certs_ids,
+                   int n_trusted_certs, uint32_t trusted_cert_set)
 {
  gnutls_certificate_credentials_t credentials = NULL;
-  int r;
+  int i, r;

-  init_gnutls();
+  if (!init_gnutls())
+    return NULL;

  r = gnutls_certificate_allocate_credentials(&credentials);
  if (r < 0)
    goto error;

-  if (cert && key) {
-    r = gnutls_certificate_set_x509_key_file(credentials, cert, key,
-                                             GNUTLS_X509_FMT_PEM);
-    if (r < 0)
-      goto error;
+  if (certs && keys) {
+    if (trusted_certs || trusted_certs_ids)
+      assert(0);
+
+    for (i = 0; i < n_certs_keys; i++) {
+      if (!UTI_CheckFilePermissions(keys[i], 0771))
+        ;
+      r = gnutls_certificate_set_x509_key_file(credentials, certs[i], keys[i],
+                                               GNUTLS_X509_FMT_PEM);
+      if (r < 0)
+        goto error;
+    }
  } else {
-    if (!CNF_GetNoSystemCert()) {
+    if (certs || keys || n_certs_keys > 0)
+      assert(0);
+
+    if (trusted_cert_set == 0 && !CNF_GetNoSystemCert()) {
      r = gnutls_certificate_set_x509_system_trust(credentials);
      if (r < 0)
        goto error;
    }

-    if (trusted_certs) {
-      r = gnutls_certificate_set_x509_trust_file(credentials, trusted_certs,
-                                                 GNUTLS_X509_FMT_PEM);
-      if (r < 0)
-        goto error;
+    if (trusted_certs && trusted_certs_ids) {
+      for (i = 0; i < n_trusted_certs; i++) {
+        struct stat buf;
+
+        if (trusted_certs_ids[i] != trusted_cert_set)
+          continue;
+
+        if (stat(trusted_certs[i], &buf) == 0 && S_ISDIR(buf.st_mode))
+          r = gnutls_certificate_set_x509_trust_dir(credentials, trusted_certs[i],
+                                                    GNUTLS_X509_FMT_PEM);
+        else
+          r = gnutls_certificate_set_x509_trust_file(credentials, trusted_certs[i],
+                                                     GNUTLS_X509_FMT_PEM);
+        if (r < 0)
+          goto error;
+
+        DEBUG_LOG("Added %d trusted certs from %s", r, trusted_certs[i]);
+      }
    }
  }

  credentials_counter++;

-  return credentials;
+  return (NKSN_Credentials)credentials;

 error:
  LOG(LOGS_ERR, "Could not set credentials : %s", gnutls_strerror(r));
  if (credentials)
    gnutls_certificate_free_credentials(credentials);
+  deinit_gnutls();
  return NULL;
 }

 /* ================================================== */

-void
-NKSN_DestroyCertCredentials(void *credentials)
+NKSN_Credentials
+NKSN_CreateServerCertCredentials(const char **certs, const char **keys, int n_certs_keys)
 {
-  gnutls_certificate_free_credentials(credentials);
-  credentials_counter--;
-  if (credentials_counter != 0)
-    return;
+  return create_credentials(certs, keys, n_certs_keys, NULL, NULL, 0, 0);
+}

+/* ================================================== */
+
+NKSN_Credentials
+NKSN_CreateClientCertCredentials(const char **certs, uint32_t *ids,
+                                 int n_certs_ids, uint32_t trusted_cert_set)
+{
+  return create_credentials(NULL, NULL, 0, certs, ids, n_certs_ids, trusted_cert_set);
+}
+
+/* ================================================== */
+
+void
+NKSN_DestroyCertCredentials(NKSN_Credentials credentials)
+{
+  gnutls_certificate_free_credentials((gnutls_certificate_credentials_t)credentials);
+  credentials_counter--;
  deinit_gnutls();
 }

 /* ================================================== */

 NKSN_Instance
-NKSN_CreateInstance(int server_mode, const char *name,
+NKSN_CreateInstance(int server_mode, const char *server_name,
                    NKSN_MessageHandler handler, void *handler_arg)
 {
  NKSN_Instance inst;
@@ -628,17 +755,19 @@ NKSN_CreateInstance(int server_mode, const char *name,
  inst = MallocNew(struct NKSN_Instance_Record);

  inst->server = server_mode;
-  inst->name = Strdup(name);
+  inst->server_name = server_name ? Strdup(server_name) : NULL;
  inst->handler = handler;
  inst->handler_arg = handler_arg;
-  /* Replace NULL arg with the session itself */
+  /* Replace a NULL argument with the session itself */
  if (!inst->handler_arg)
    inst->handler_arg = inst;

  inst->state = KE_STOPPED;
  inst->sock_fd = INVALID_SOCK_FD;
+  inst->label = NULL;
  inst->tls_session = NULL;
  inst->timeout_id = 0;
+  inst->retry_factor = NKE_RETRY_FACTOR2_CONNECT;

  return inst;
 }
@@ -650,31 +779,33 @@ NKSN_DestroyInstance(NKSN_Instance inst)
 {
  stop_session(inst);

-  Free(inst->name);
+  Free(inst->server_name);
  Free(inst);
 }

 /* ================================================== */

 int
-NKSN_StartSession(NKSN_Instance inst, int sock_fd, void *credentials, double timeout)
+NKSN_StartSession(NKSN_Instance inst, int sock_fd, const char *label,
+                  NKSN_Credentials credentials, double timeout)
 {
  assert(inst->state == KE_STOPPED);

-  inst->tls_session = create_tls_session(inst->server, sock_fd,
-                                         inst->server ? NULL : inst->name,
-                                         credentials, priority_cache);
+  inst->tls_session = create_tls_session(inst->server, sock_fd, inst->server_name,
+                                         (gnutls_certificate_credentials_t)credentials,
+                                         priority_cache);
  if (!inst->tls_session)
    return 0;

  inst->sock_fd = sock_fd;
  SCH_AddFileHandler(sock_fd, SCH_FILE_INPUT, read_write_socket, inst);

+  inst->label = Strdup(label);
  inst->timeout_id = SCH_AddTimeoutByDelay(timeout, session_timeout, inst);
+  inst->retry_factor = NKE_RETRY_FACTOR2_CONNECT;

  reset_message(&inst->message);
  inst->new_message = 0;
-  inst->ended_message = 0;

  change_state(inst, inst->server ? KE_HANDSHAKE : KE_WAIT_CONNECT);

@@ -708,6 +839,7 @@ NKSN_EndMessage(NKSN_Instance inst)
 {
  assert(!inst->message.complete);

+  /* Terminate the message */
  if (!add_record(&inst->message, 1, NKE_RECORD_END_OF_MESSAGE, NULL, 0))
    return 0;

@@ -726,9 +858,13 @@ NKSN_GetRecord(NKSN_Instance inst, int *critical, int *type, int *body_length,

  assert(inst->message.complete);

+  if (body_length)
+    *body_length = 0;
+
  if (!get_record(&inst->message, critical, &type2, body_length, body, buffer_length))
    return 0;

+  /* Hide the end-of-message record */
  if (type2 == NKE_RECORD_END_OF_MESSAGE)
    return 0;

@@ -743,21 +879,27 @@ NKSN_GetRecord(NKSN_Instance inst, int *critical, int *type, int *body_length,
 int
 NKSN_GetKeys(NKSN_Instance inst, SIV_Algorithm siv, NKE_Key *c2s, NKE_Key *s2c)
 {
-  c2s->length = SIV_GetKeyLength(siv);
-  s2c->length = SIV_GetKeyLength(siv);
-  assert(c2s->length <= sizeof (c2s->key));
-  assert(s2c->length <= sizeof (s2c->key));
+  int length = SIV_GetKeyLength(siv);
+
+  if (length <= 0 || length > sizeof (c2s->key) || length > sizeof (s2c->key)) {
+    DEBUG_LOG("Invalid algorithm");
+    return 0;
+  }

  if (gnutls_prf_rfc5705(inst->tls_session,
                         sizeof (NKE_EXPORTER_LABEL) - 1, NKE_EXPORTER_LABEL,
                         sizeof (NKE_EXPORTER_CONTEXT_C2S) - 1, NKE_EXPORTER_CONTEXT_C2S,
-                         c2s->length, (char *)c2s->key) < 0)
-    return 0;
-  if (gnutls_prf_rfc5705(inst->tls_session,
+                         length, (char *)c2s->key) < 0 ||
+      gnutls_prf_rfc5705(inst->tls_session,
                         sizeof (NKE_EXPORTER_LABEL) - 1, NKE_EXPORTER_LABEL,
                         sizeof (NKE_EXPORTER_CONTEXT_S2C) - 1, NKE_EXPORTER_CONTEXT_S2C,
-                         s2c->length, (char *)s2c->key) < 0)
+                         length, (char *)s2c->key) < 0) {
+    DEBUG_LOG("Could not export key");
    return 0;
+  }
+
+  c2s->length = length;
+  s2c->length = length;

  return 1;
 }
@@ -777,3 +919,11 @@ NKSN_StopSession(NKSN_Instance inst)
 {
  stop_session(inst);
 }
+
+/* ================================================== */
+
+int
+NKSN_GetRetryFactor(NKSN_Instance inst)
+{
+  return inst->retry_factor;
+}
--- a/nts_ke_session.h
+++ b/nts_ke_session.h
@@ -30,30 +30,36 @@
 #include "nts_ke.h"
 #include "siv.h"

+typedef struct NKSN_Credentials_Record *NKSN_Credentials;
+
 typedef struct NKSN_Instance_Record *NKSN_Instance;

-/* Handler for received NTS-KE messages.  A non-zero return code stops
+/* Handler for received NTS-KE messages.  A zero return code stops
   the session. */
 typedef int (*NKSN_MessageHandler)(void *arg);

-/* Get client or server credentials using certificates of trusted CAs,
-   or a server certificate and key.  The credentials may be shared between
+/* Get server or client credentials using a server certificate and key,
+   or certificates of trusted CAs.  The credentials may be shared between
   different clients or servers. */
-extern void *NKSN_CreateCertCredentials(char *cert, char *key, char *trusted_certs);
+extern NKSN_Credentials NKSN_CreateServerCertCredentials(const char **certs, const char **keys,
+                                                         int n_certs_keys);
+extern NKSN_Credentials NKSN_CreateClientCertCredentials(const char **certs, uint32_t *ids,
+                                                         int n_certs_ids,
+                                                         uint32_t trusted_cert_set);

 /* Destroy the credentials */
-extern void NKSN_DestroyCertCredentials(void *credentials);
+extern void NKSN_DestroyCertCredentials(NKSN_Credentials credentials);

 /* Create an instance */
-extern NKSN_Instance NKSN_CreateInstance(int server_mode, const char *name,
+extern NKSN_Instance NKSN_CreateInstance(int server_mode, const char *server_name,
                                         NKSN_MessageHandler handler, void *handler_arg);

 /* Destroy an instance */
 extern void NKSN_DestroyInstance(NKSN_Instance inst);

 /* Start a new NTS-KE session */
-extern int NKSN_StartSession(NKSN_Instance inst, int sock_fd, void *credentials,
-                             double timeout);
+extern int NKSN_StartSession(NKSN_Instance inst, int sock_fd, const char *label,
+                             NKSN_Credentials credentials, double timeout);

 /* Begin an NTS-KE message.  A request should be made right after starting
   the session and response should be made in the message handler. */
@@ -80,4 +86,8 @@ extern int NKSN_IsStopped(NKSN_Instance inst);
 /* Stop the session */
 extern void NKSN_StopSession(NKSN_Instance inst);

+/* Get a factor to calculate retry interval (in log2 seconds)
+   based on the session state or how it was terminated */
+extern int NKSN_GetRetryFactor(NKSN_Instance inst);
+
 #endif
--- a/nts_ntp.h
+++ b/nts_ntp.h
@@ -27,11 +27,6 @@
 #ifndef GOT_NTS_NTP_H
 #define GOT_NTS_NTP_H

-#define NTP_EF_NTS_UNIQUE_IDENTIFIER    0x0104
-#define NTP_EF_NTS_COOKIE               0x0204
-#define NTP_EF_NTS_COOKIE_PLACEHOLDER   0x0304
-#define NTP_EF_NTS_AUTH_AND_EEF         0x0404
-
 #define NTP_KOD_NTS_NAK                 0x4e54534e

 #define NTS_MIN_UNIQ_ID_LENGTH          32
--- a/nts_ntp_auth.c
+++ b/nts_ntp_auth.c
@@ -61,23 +61,25 @@ get_padded_length(int length)

 int
 NNA_GenerateAuthEF(NTP_Packet *packet, NTP_PacketInfo *info, SIV_Instance siv,
-                   const unsigned char *nonce, int nonce_length,
+                   const unsigned char *nonce, int max_nonce_length,
                   const unsigned char *plaintext, int plaintext_length,
                   int min_ef_length)
 {
-  int auth_length, ciphertext_length, assoc_length;
+  int auth_length, ciphertext_length, assoc_length, nonce_length, max_siv_nonce_length;
  int nonce_padding, ciphertext_padding, additional_padding;
  unsigned char *ciphertext, *body;
  struct AuthHeader *header;

  assert(sizeof (*header) == 4);

-  if (nonce_length <= 0 || plaintext_length < 0) {
+  if (max_nonce_length <= 0 || plaintext_length < 0) {
    DEBUG_LOG("Invalid nonce/plaintext length");
    return 0;
  }

  assoc_length = info->length;
+  max_siv_nonce_length = SIV_GetMaxNonceLength(siv);
+  nonce_length = MIN(max_nonce_length, max_siv_nonce_length);
  ciphertext_length = SIV_GetTagLength(siv) + plaintext_length;
  nonce_padding = get_padding_length(nonce_length);
  ciphertext_padding = get_padding_length(ciphertext_length);
@@ -86,8 +88,8 @@ NNA_GenerateAuthEF(NTP_Packet *packet, NTP_PacketInfo *info, SIV_Instance siv,
  auth_length = sizeof (*header) + nonce_length + nonce_padding +
                ciphertext_length + ciphertext_padding;
  additional_padding = MAX(min_ef_length - auth_length - 4, 0);
-  additional_padding = MAX(NTS_MIN_UNPADDED_NONCE_LENGTH - nonce_length - nonce_padding,
-                           additional_padding);
+  additional_padding = MAX(MIN(NTS_MIN_UNPADDED_NONCE_LENGTH, max_siv_nonce_length) -
+                           nonce_length - nonce_padding, additional_padding);
  auth_length += additional_padding;

  if (!NEF_AddBlankField(packet, info, NTP_EF_NTS_AUTH_AND_EEF, auth_length,
@@ -102,12 +104,18 @@ NNA_GenerateAuthEF(NTP_Packet *packet, NTP_PacketInfo *info, SIV_Instance siv,
  body = (unsigned char *)(header + 1);
  ciphertext = body + nonce_length + nonce_padding;

+  if ((unsigned char *)header + auth_length !=
+      ciphertext + ciphertext_length + ciphertext_padding + additional_padding)
+    assert(0);
+
  memcpy(body, nonce, nonce_length);
  memset(body + nonce_length, 0, nonce_padding);

  if (!SIV_Encrypt(siv, nonce, nonce_length, packet, assoc_length,
                   plaintext, plaintext_length, ciphertext, ciphertext_length)) {
    DEBUG_LOG("SIV encrypt failed");
+    info->length = assoc_length;
+    info->ext_fields--;
    return 0;
  }

@@ -122,17 +130,20 @@ int
 NNA_DecryptAuthEF(NTP_Packet *packet, NTP_PacketInfo *info, SIV_Instance siv, int ef_start,
                  unsigned char *plaintext, int buffer_length, int *plaintext_length)
 {
-  unsigned int siv_tag_length, nonce_length, ciphertext_length;
+  int siv_tag_length, max_siv_nonce_length, nonce_length, ciphertext_length;
  unsigned char *nonce, *ciphertext;
  int ef_type, ef_body_length;
  void *ef_body;
  struct AuthHeader *header;

+  if (buffer_length < 0)
+    return 0;
+
  if (!NEF_ParseField(packet, info->length, ef_start,
                      NULL, &ef_type, &ef_body, &ef_body_length))
    return 0;

-  if (ef_type != NTP_EF_NTS_AUTH_AND_EEF)
+  if (ef_type != NTP_EF_NTS_AUTH_AND_EEF || ef_body_length < sizeof (*header))
    return 0;

  header = ef_body;
@@ -145,8 +156,9 @@ NNA_DecryptAuthEF(NTP_Packet *packet, NTP_PacketInfo *info, SIV_Instance siv, in
    return 0;

  nonce = (unsigned char *)(header + 1);
-  ciphertext = (unsigned char *)(header + 1) + get_padded_length(nonce_length);
+  ciphertext = nonce + get_padded_length(nonce_length);

+  max_siv_nonce_length = SIV_GetMaxNonceLength(siv);
  siv_tag_length = SIV_GetTagLength(siv);

  if (nonce_length < 1 ||
@@ -156,15 +168,16 @@ NNA_DecryptAuthEF(NTP_Packet *packet, NTP_PacketInfo *info, SIV_Instance siv, in
    return 0;
  }

-  if (ef_body_length < sizeof (*header) +
-        NTS_MIN_UNPADDED_NONCE_LENGTH + get_padded_length(ciphertext_length)) {
+  if (sizeof (*header) + MIN(NTS_MIN_UNPADDED_NONCE_LENGTH, max_siv_nonce_length) +
+      get_padded_length(ciphertext_length) > ef_body_length) {
    DEBUG_LOG("Missing padding");
    return 0;
  }

  *plaintext_length = ciphertext_length - siv_tag_length;
+  assert(*plaintext_length >= 0);

-  if (!SIV_Decrypt(siv, nonce, nonce_length, packet, info->length - ef_body_length - 4,
+  if (!SIV_Decrypt(siv, nonce, nonce_length, packet, ef_start,
                   ciphertext, ciphertext_length, plaintext, *plaintext_length)) {
    DEBUG_LOG("SIV decrypt failed");
    return 0;
--- a/nts_ntp_auth.h
+++ b/nts_ntp_auth.h
@@ -32,7 +32,7 @@
 #include "siv.h"

 extern int NNA_GenerateAuthEF(NTP_Packet *packet, NTP_PacketInfo *info, SIV_Instance siv,
-                              const unsigned char *nonce, int nonce_length,
+                              const unsigned char *nonce, int max_nonce_length,
                              const unsigned char *plaintext, int plaintext_length,
                              int min_ef_length);

--- a/nts_ntp_client.c
+++ b/nts_ntp_client.c
@@ -43,22 +43,40 @@
 #include "siv.h"
 #include "util.h"

+/* Maximum length of all cookies to avoid IP fragmentation */
 #define MAX_TOTAL_COOKIE_LENGTH (8 * 108)
-#define MIN_NKE_RETRY_INTERVAL 1000
+
+/* Retry interval for NTS-KE start (which doesn't generate network traffic) */
+#define RETRY_INTERVAL_KE_START 2.0
+
+/* Magic string of files containing keys and cookies */
+#define DUMP_IDENTIFIER "NNC0\n"

 struct NNC_Instance_Record {
-  const IPSockAddr *ntp_address;
+  /* Address of NTS-KE server */
  IPSockAddr nts_address;
+  /* Hostname or IP address for certificate verification */
  char *name;
-  SIV_Instance siv_c2s;
-  SIV_Instance siv_s2c;
-  NKC_Instance nke;
+  /* ID of trusted certificates */
+  uint32_t cert_set;
+  /* Configured NTP port */
+  uint16_t default_ntp_port;
+  /* Address of NTP server (can be negotiated in NTS-KE) */
+  IPSockAddr ntp_address;

-  double last_nke_attempt;
+  NKC_Instance nke;
+  SIV_Instance siv;
+
+  int nke_attempts;
+  double next_nke_attempt;
  double last_nke_success;
+
+  NKE_Context context;
+  unsigned int context_id;
  NKE_Cookie cookies[NTS_MAX_COOKIES];
  int num_cookies;
  int cookie_index;
+  int auth_ready;
  int nak_response;
  int ok_response;
  unsigned char nonce[NTS_MIN_UNPADDED_NONCE_LENGTH];
@@ -67,13 +85,31 @@ struct NNC_Instance_Record {

 /* ================================================== */

+static void save_cookies(NNC_Instance inst);
+static void load_cookies(NNC_Instance inst);
+
+/* ================================================== */
+
 static void
 reset_instance(NNC_Instance inst)
 {
-  inst->last_nke_attempt = -MIN_NKE_RETRY_INTERVAL;
+  if (inst->nke)
+    NKC_DestroyInstance(inst->nke);
+  inst->nke = NULL;
+  if (inst->siv)
+    SIV_DestroyInstance(inst->siv);
+  inst->siv = NULL;
+
+  inst->nke_attempts = 0;
+  inst->next_nke_attempt = 0.0;
  inst->last_nke_success = 0.0;
+
+  memset(&inst->context, 0, sizeof (inst->context));
+  inst->context_id = 0;
+  memset(inst->cookies, 0, sizeof (inst->cookies));
  inst->num_cookies = 0;
  inst->cookie_index = 0;
+  inst->auth_ready = 0;
  inst->nak_response = 0;
  inst->ok_response = 1;
  memset(inst->nonce, 0, sizeof (inst->nonce));
@@ -83,21 +119,26 @@ reset_instance(NNC_Instance inst)
 /* ================================================== */

 NNC_Instance
-NNC_CreateInstance(IPSockAddr *nts_address, const char *name, const IPSockAddr *ntp_address)
+NNC_CreateInstance(IPSockAddr *nts_address, const char *name, uint32_t cert_set, uint16_t ntp_port)
 {
  NNC_Instance inst;

  inst = MallocNew(struct NNC_Instance_Record);

-  inst->ntp_address = ntp_address;
  inst->nts_address = *nts_address;
-  inst->name = name ? Strdup(name) : NULL;
-  inst->siv_c2s = NULL;
-  inst->siv_s2c = NULL;
+  inst->name = Strdup(name);
+  inst->cert_set = cert_set;
+  inst->default_ntp_port = ntp_port;
+  inst->ntp_address.ip_addr = nts_address->ip_addr;
+  inst->ntp_address.port = ntp_port;
+  inst->siv = NULL;
  inst->nke = NULL;

  reset_instance(inst);

+  /* Try to reload saved keys and cookies */
+  load_cookies(inst);
+
  return inst;
 }

@@ -106,12 +147,9 @@ NNC_CreateInstance(IPSockAddr *nts_address, const char *name, const IPSockAddr *
 void
 NNC_DestroyInstance(NNC_Instance inst)
 {
-  if (inst->nke)
-    NKC_DestroyInstance(inst->nke);
-  if (inst->siv_c2s)
-    SIV_DestroyInstance(inst->siv_c2s);
-  if (inst->siv_s2c)
-    SIV_DestroyInstance(inst->siv_s2c);
+  save_cookies(inst);
+
+  reset_instance(inst);

  Free(inst->name);
  Free(inst);
@@ -120,20 +158,18 @@ NNC_DestroyInstance(NNC_Instance inst)
 /* ================================================== */

 static int
-is_nke_needed(NNC_Instance inst)
+check_cookies(NNC_Instance inst)
 {
-  /* Force NKE if a NAK was received since last valid auth */
-  if (inst->nak_response && !inst->ok_response && inst->num_cookies > 0) {
+  /* Force a new NTS-KE session if a NAK was received without a valid response,
+     or the keys encrypting the cookies need to be refreshed */
+  if (inst->num_cookies > 0 &&
+      ((inst->nak_response && !inst->ok_response) ||
+       SCH_GetLastEventMonoTime() - inst->last_nke_success > CNF_GetNtsRefresh())) {
    inst->num_cookies = 0;
    DEBUG_LOG("Dropped cookies");
  }

-  /* Force NKE if the keys encrypting the cookies are too old */
-  if (inst->num_cookies > 0 &&
-      SCH_GetLastEventMonoTime() - inst->last_nke_success > CNF_GetNtsRefresh())
-    inst->num_cookies = 0;
-
-  return inst->num_cookies == 0;
+  return inst->num_cookies > 0;
 }

 /* ================================================== */
@@ -143,13 +179,13 @@ set_ntp_address(NNC_Instance inst, NTP_Remote_Address *negotiated_address)
 {
  NTP_Remote_Address old_address, new_address;

-  old_address = *inst->ntp_address;
+  old_address = inst->ntp_address;
  new_address = *negotiated_address;

  if (new_address.ip_addr.family == IPADDR_UNSPEC)
-    new_address.ip_addr = old_address.ip_addr;
+    new_address.ip_addr = inst->nts_address.ip_addr;
  if (new_address.port == 0)
-    new_address.port = old_address.port;
+    new_address.port = inst->default_ntp_port;

  if (UTI_CompareIPs(&old_address.ip_addr, &new_address.ip_addr, NULL) == 0 &&
      old_address.port == new_address.port)
@@ -162,83 +198,94 @@ set_ntp_address(NNC_Instance inst, NTP_Remote_Address *negotiated_address)
    return 0;
  }

+  inst->ntp_address = new_address;
+
  return 1;
 }

 /* ================================================== */

+static void
+update_next_nke_attempt(NNC_Instance inst, int failed_start, double now)
+{
+  int factor, interval;
+
+  if (failed_start) {
+    inst->next_nke_attempt = now + RETRY_INTERVAL_KE_START;
+    return;
+  }
+
+  if (!inst->nke)
+    return;
+
+  factor = NKC_GetRetryFactor(inst->nke);
+  interval = MIN(factor + inst->nke_attempts - 1, NKE_MAX_RETRY_INTERVAL2);
+  inst->next_nke_attempt = now + UTI_Log2ToDouble(interval);
+}
+
+/* ================================================== */
+
 static int
-get_nke_data(NNC_Instance inst)
+get_cookies(NNC_Instance inst)
 {
  NTP_Remote_Address ntp_address;
-  SIV_Algorithm siv;
-  NKE_Key c2s, s2c;
+  int got_data, failed_start = 0;
  double now;
-  int got_data;

-  assert(is_nke_needed(inst));
+  assert(inst->num_cookies == 0);

  now = SCH_GetLastEventMonoTime();

+  /* Create and start a new NTS-KE session if not already present */
  if (!inst->nke) {
-    if (now - inst->last_nke_attempt < MIN_NKE_RETRY_INTERVAL) {
-      DEBUG_LOG("Limiting NTS-KE request rate");
+    if (now < inst->next_nke_attempt) {
+      DEBUG_LOG("Limiting NTS-KE request rate (%f seconds)",
+                inst->next_nke_attempt - now);
      return 0;
    }

-    if (!inst->name) {
-      LOG(LOGS_ERR, "Missing name of %s for NTS-KE",
-          UTI_IPToString(&inst->nts_address.ip_addr));
-      return 0;
-    }
+    inst->nke = NKC_CreateInstance(&inst->nts_address, inst->name, inst->cert_set);

-    inst->nke = NKC_CreateInstance(&inst->nts_address, inst->name);
+    inst->nke_attempts++;

    if (!NKC_Start(inst->nke))
-      return 0;
-
-    inst->last_nke_attempt = now;
+      failed_start = 1;
  }

+  update_next_nke_attempt(inst, failed_start, now);
+
+  /* Wait until the session stops */
  if (NKC_IsActive(inst->nke))
    return 0;

-  got_data = NKC_GetNtsData(inst->nke, &siv, &c2s, &s2c,
+  assert(sizeof (inst->cookies) / sizeof (inst->cookies[0]) == NTS_MAX_COOKIES);
+
+  /* Get the new keys, cookies and NTP address if the session was successful */
+  got_data = NKC_GetNtsData(inst->nke, &inst->context,
                            inst->cookies, &inst->num_cookies, NTS_MAX_COOKIES,
                            &ntp_address);

  NKC_DestroyInstance(inst->nke);
  inst->nke = NULL;
-  
+
  if (!got_data)
    return 0;

+  if (inst->siv)
+    SIV_DestroyInstance(inst->siv);
+  inst->siv = NULL;
+
+  inst->context_id++;
+
+  /* Force a new session if the NTP address is used by another source, with
+     an expectation that it will eventually get a non-conflicting address */
  if (!set_ntp_address(inst, &ntp_address)) {
    inst->num_cookies = 0;
    return 0;
  }

-  inst->cookie_index = 0;
-
-  if (inst->siv_c2s)
-    SIV_DestroyInstance(inst->siv_c2s);
-  if (inst->siv_s2c)
-    SIV_DestroyInstance(inst->siv_s2c);
-
-  inst->siv_c2s = SIV_CreateInstance(siv);
-  inst->siv_s2c = SIV_CreateInstance(siv);
-
-  if (!inst->siv_c2s || !inst->siv_s2c ||
-      !SIV_SetKey(inst->siv_c2s, c2s.key, c2s.length) ||
-      !SIV_SetKey(inst->siv_s2c, s2c.key, s2c.length)) {
-    DEBUG_LOG("Could not initialise SIV");
-    inst->num_cookies = 0;
-    return 0;
-  }
-
-  inst->nak_response = 0;
-
  inst->last_nke_success = now;
+  inst->cookie_index = 0;

  return 1;
 }
@@ -248,13 +295,31 @@ get_nke_data(NNC_Instance inst)
 int
 NNC_PrepareForAuth(NNC_Instance inst)
 {
-  if (is_nke_needed(inst)) {
-    if (!get_nke_data(inst))
+  inst->auth_ready = 0;
+
+  /* Prepare data for the next request and invalidate any responses to the
+     previous request */
+  UTI_GetRandomBytes(inst->uniq_id, sizeof (inst->uniq_id));
+  UTI_GetRandomBytes(inst->nonce, sizeof (inst->nonce));
+
+  /* Get new cookies if there are not any, or they are no longer usable */
+  if (!check_cookies(inst)) {
+    if (!get_cookies(inst))
      return 0;
  }

-  UTI_GetRandomBytes(&inst->uniq_id, sizeof (inst->uniq_id));
-  UTI_GetRandomBytes(&inst->nonce, sizeof (inst->nonce));
+  inst->nak_response = 0;
+
+  if (!inst->siv)
+    inst->siv = SIV_CreateInstance(inst->context.algorithm);
+
+  if (!inst->siv ||
+      !SIV_SetKey(inst->siv, inst->context.c2s.key, inst->context.c2s.length)) {
+    DEBUG_LOG("Could not set SIV key");
+    return 0;
+  }
+
+  inst->auth_ready = 1;

  return 1;
 }
@@ -267,19 +332,28 @@ NNC_GenerateRequestAuth(NNC_Instance inst, NTP_Packet *packet,
 {
  NKE_Cookie *cookie;
  int i, req_cookies;
+  void *ef_body;

-  if (inst->num_cookies == 0 || !inst->siv_c2s)
+  if (!inst->auth_ready)
+    return 0;
+
+  inst->auth_ready = 0;
+
+  if (inst->num_cookies <= 0 || !inst->siv)
    return 0;

  if (info->mode != MODE_CLIENT)
    return 0;

  cookie = &inst->cookies[inst->cookie_index];
-  req_cookies = MIN(NTS_MAX_COOKIES - inst->num_cookies + 1,
+  inst->num_cookies--;
+  inst->cookie_index = (inst->cookie_index + 1) % NTS_MAX_COOKIES;
+
+  req_cookies = MIN(NTS_MAX_COOKIES - inst->num_cookies,
                    MAX_TOTAL_COOKIE_LENGTH / (cookie->length + 4));

  if (!NEF_AddField(packet, info, NTP_EF_NTS_UNIQUE_IDENTIFIER,
-                    &inst->uniq_id, sizeof (inst->uniq_id)))
+                    inst->uniq_id, sizeof (inst->uniq_id)))
    return 0;

  if (!NEF_AddField(packet, info, NTP_EF_NTS_COOKIE,
@@ -287,17 +361,16 @@ NNC_GenerateRequestAuth(NNC_Instance inst, NTP_Packet *packet,
    return 0;

  for (i = 0; i < req_cookies - 1; i++) {
-    if (!NEF_AddField(packet, info, NTP_EF_NTS_COOKIE_PLACEHOLDER,
-                      cookie->cookie, cookie->length))
+    if (!NEF_AddBlankField(packet, info, NTP_EF_NTS_COOKIE_PLACEHOLDER,
+                           cookie->length, &ef_body))
      return 0;
+    memset(ef_body, 0, cookie->length);
  }

-  if (!NNA_GenerateAuthEF(packet, info, inst->siv_c2s, inst->nonce, sizeof (inst->nonce),
+  if (!NNA_GenerateAuthEF(packet, info, inst->siv, inst->nonce, sizeof (inst->nonce),
                          (const unsigned char *)"", 0, NTP_MAX_V4_MAC_LENGTH + 4))
    return 0;

-  inst->num_cookies--;
-  inst->cookie_index = (inst->cookie_index + 1) % NTS_MAX_COOKIES;
  inst->ok_response = 0;

  return 1;
@@ -305,6 +378,23 @@ NNC_GenerateRequestAuth(NNC_Instance inst, NTP_Packet *packet,

 /* ================================================== */

+static int
+parse_encrypted_efs(NNC_Instance inst, unsigned char *plaintext, int length)
+{
+  int ef_length, parsed;
+
+  for (parsed = 0; parsed < length; parsed += ef_length) {
+    if (!NEF_ParseSingleField(plaintext, length, parsed, &ef_length, NULL, NULL, NULL)) {
+      DEBUG_LOG("Could not parse encrypted EF");
+      return 0;
+    }
+  }
+
+  return 1;
+}
+
+/* ================================================== */
+
 static int
 extract_cookies(NNC_Instance inst, unsigned char *plaintext, int length)
 {
@@ -316,7 +406,7 @@ extract_cookies(NNC_Instance inst, unsigned char *plaintext, int length)
  for (parsed = 0; parsed < length; parsed += ef_length) {
    if (!NEF_ParseSingleField(plaintext, length, parsed,
                              &ef_length, &ef_type, &ef_body, &ef_body_length))
-      break;
+      return 0;

    if (ef_type != NTP_EF_NTS_COOKIE)
      continue;
@@ -332,6 +422,9 @@ extract_cookies(NNC_Instance inst, unsigned char *plaintext, int length)
      continue;

    index = (inst->cookie_index + inst->num_cookies) % NTS_MAX_COOKIES;
+    assert(index >= 0 && index < NTS_MAX_COOKIES);
+    assert(sizeof (inst->cookies) / sizeof (inst->cookies[0]) == NTS_MAX_COOKIES);
+
    memcpy(inst->cookies[index].cookie, ef_body, ef_body_length);
    inst->cookies[index].length = ef_body_length;
    inst->num_cookies++;
@@ -358,17 +451,21 @@ NNC_CheckResponseAuth(NNC_Instance inst, NTP_Packet *packet,
  if (info->ext_fields == 0 || info->mode != MODE_SERVER)
    return 0;

-  /* Accept only one response per request */
-  if (inst->ok_response)
+  /* Accept at most one response per request */
+  if (inst->ok_response || inst->auth_ready)
    return 0;

-  if (!inst->siv_s2c)
+  if (!inst->siv ||
+      !SIV_SetKey(inst->siv, inst->context.s2c.key, inst->context.s2c.length)) {
+    DEBUG_LOG("Could not set SIV key");
    return 0;
+  }

  for (parsed = NTP_HEADER_LENGTH; parsed < info->length; parsed += ef_length) {
    if (!NEF_ParseField(packet, info->length, parsed,
                        &ef_length, &ef_type, &ef_body, &ef_body_length))
-      break;
+      /* This is not expected as the packet already passed parsing */
+      return 0;

    switch (ef_type) {
      case NTP_EF_NTS_UNIQUE_IDENTIFIER:
@@ -388,10 +485,13 @@ NNC_CheckResponseAuth(NNC_Instance inst, NTP_Packet *packet,
          return 0;
        }

-        if (!NNA_DecryptAuthEF(packet, info, inst->siv_s2c, parsed,
+        if (!NNA_DecryptAuthEF(packet, info, inst->siv, parsed,
                               plaintext, sizeof (plaintext), &plaintext_length))
          return 0;

+        if (!parse_encrypted_efs(inst, plaintext, plaintext_length))
+          return 0;
+
        has_valid_auth = 1;
        break;
      default:
@@ -418,7 +518,8 @@ NNC_CheckResponseAuth(NNC_Instance inst, NTP_Packet *packet,

  /* At this point we know the client interoperates with the server.  Allow a
     new NTS-KE session to be started as soon as the cookies run out. */
-  inst->last_nke_attempt = -MIN_NKE_RETRY_INTERVAL;
+  inst->nke_attempts = 0;
+  inst->next_nke_attempt = 0.0;

  return 1;
 }
@@ -428,14 +529,189 @@ NNC_CheckResponseAuth(NNC_Instance inst, NTP_Packet *packet,
 void
 NNC_ChangeAddress(NNC_Instance inst, IPAddr *address)
 {
-  if (inst->nke)
-    NKC_DestroyInstance(inst->nke);
+  save_cookies(inst);

-  inst->nke = NULL;
-  inst->num_cookies = 0;
  inst->nts_address.ip_addr = *address;
+  inst->ntp_address.ip_addr = *address;

  reset_instance(inst);

  DEBUG_LOG("NTS reset");
+
+  load_cookies(inst);
+}
+
+/* ================================================== */
+
+static void
+save_cookies(NNC_Instance inst)
+{
+  char buf[2 * NKE_MAX_COOKIE_LENGTH + 2], *dump_dir, *filename;
+  struct timespec now;
+  double context_time;
+  FILE *f;
+  int i;
+
+  if (inst->num_cookies < 1 || !UTI_IsIPReal(&inst->nts_address.ip_addr))
+    return;
+
+  dump_dir = CNF_GetNtsDumpDir();
+  if (!dump_dir)
+    return;
+
+  filename = UTI_IPToString(&inst->nts_address.ip_addr);
+
+  f = UTI_OpenFile(dump_dir, filename, ".tmp", 'w', 0600);
+  if (!f)
+    return;
+
+  SCH_GetLastEventTime(&now, NULL, NULL);
+  context_time = inst->last_nke_success - SCH_GetLastEventMonoTime();
+  context_time += UTI_TimespecToDouble(&now);
+
+  if (fprintf(f, "%s%s\n%.1f\n%s %d\n%u %d ",
+              DUMP_IDENTIFIER, inst->name, context_time,
+              UTI_IPToString(&inst->ntp_address.ip_addr), inst->ntp_address.port,
+              inst->context_id, (int)inst->context.algorithm) < 0 ||
+      !UTI_BytesToHex(inst->context.s2c.key, inst->context.s2c.length, buf, sizeof (buf)) ||
+      fprintf(f, "%s ", buf) < 0 ||
+      !UTI_BytesToHex(inst->context.c2s.key, inst->context.c2s.length, buf, sizeof (buf)) ||
+      fprintf(f, "%s\n", buf) < 0)
+    goto error;
+
+  for (i = 0; i < inst->num_cookies; i++) {
+    if (!UTI_BytesToHex(inst->cookies[i].cookie, inst->cookies[i].length, buf, sizeof (buf)) ||
+        fprintf(f, "%s\n", buf) < 0)
+      goto error;
+  }
+
+  fclose(f);
+
+  if (!UTI_RenameTempFile(dump_dir, filename, ".tmp", ".nts"))
+    ;
+  return;
+
+error:
+  DEBUG_LOG("Could not %s cookies for %s", "save", filename);
+  fclose(f);
+
+  if (!UTI_RemoveFile(dump_dir, filename, ".nts"))
+    ;
+}
+
+/* ================================================== */
+
+#define MAX_WORDS 4
+
+static void
+load_cookies(NNC_Instance inst)
+{
+  char line[2 * NKE_MAX_COOKIE_LENGTH + 2], *dump_dir, *filename, *words[MAX_WORDS];
+  unsigned int context_id;
+  int i, algorithm, port;
+  double context_time;
+  struct timespec now;
+  IPSockAddr ntp_addr;
+  FILE *f;
+
+  dump_dir = CNF_GetNtsDumpDir();
+  if (!dump_dir)
+    return;
+
+  filename = UTI_IPToString(&inst->nts_address.ip_addr);
+
+  f = UTI_OpenFile(dump_dir, filename, ".nts", 'r', 0);
+  if (!f)
+    return;
+
+  /* Don't load this file again */
+  if (!UTI_RemoveFile(dump_dir, filename, ".nts"))
+    ;
+
+  if (inst->siv)
+    SIV_DestroyInstance(inst->siv);
+  inst->siv = NULL;
+
+  if (!fgets(line, sizeof (line), f) || strcmp(line, DUMP_IDENTIFIER) != 0 ||
+      !fgets(line, sizeof (line), f) || UTI_SplitString(line, words, MAX_WORDS) != 1 ||
+        strcmp(words[0], inst->name) != 0 ||
+      !fgets(line, sizeof (line), f) || UTI_SplitString(line, words, MAX_WORDS) != 1 ||
+        sscanf(words[0], "%lf", &context_time) != 1 ||
+      !fgets(line, sizeof (line), f) || UTI_SplitString(line, words, MAX_WORDS) != 2 ||
+        !UTI_StringToIP(words[0], &ntp_addr.ip_addr) || sscanf(words[1], "%d", &port) != 1 ||
+      !fgets(line, sizeof (line), f) || UTI_SplitString(line, words, MAX_WORDS) != 4 ||
+        sscanf(words[0], "%u", &context_id) != 1 || sscanf(words[1], "%d", &algorithm) != 1)
+    goto error;
+
+  inst->context.algorithm = algorithm;
+  inst->context.s2c.length = UTI_HexToBytes(words[2], inst->context.s2c.key,
+                                            sizeof (inst->context.s2c.key));
+  inst->context.c2s.length = UTI_HexToBytes(words[3], inst->context.c2s.key,
+                                            sizeof (inst->context.c2s.key));
+
+  if (inst->context.s2c.length != SIV_GetKeyLength(algorithm) ||
+      inst->context.s2c.length <= 0 ||
+      inst->context.c2s.length != inst->context.s2c.length)
+    goto error;
+
+  for (i = 0; i < NTS_MAX_COOKIES && fgets(line, sizeof (line), f); i++) {
+    if (UTI_SplitString(line, words, MAX_WORDS) != 1)
+      goto error;
+
+    inst->cookies[i].length = UTI_HexToBytes(words[0], inst->cookies[i].cookie,
+                                             sizeof (inst->cookies[i].cookie));
+    if (inst->cookies[i].length == 0)
+      goto error;
+  }
+
+  inst->num_cookies = i;
+
+  ntp_addr.port = port;
+  if (!set_ntp_address(inst, &ntp_addr))
+    goto error;
+
+  SCH_GetLastEventTime(&now, NULL, NULL);
+  context_time -= UTI_TimespecToDouble(&now);
+  if (context_time > 0)
+    context_time = 0;
+  inst->last_nke_success = context_time + SCH_GetLastEventMonoTime();
+  inst->context_id = context_id;
+
+  fclose(f);
+
+  DEBUG_LOG("Loaded %d cookies for %s", i, filename);
+  return;
+
+error:
+  DEBUG_LOG("Could not %s cookies for %s", "load", filename);
+  fclose(f);
+
+  memset(&inst->context, 0, sizeof (inst->context));
+  inst->num_cookies = 0;
+}
+
+/* ================================================== */
+
+void
+NNC_DumpData(NNC_Instance inst)
+{
+  save_cookies(inst);
+}
+
+/* ================================================== */
+
+void
+NNC_GetReport(NNC_Instance inst, RPT_AuthReport *report)
+{
+  report->key_id = inst->context_id;
+  report->key_type = inst->context.algorithm;
+  report->key_length = 8 * inst->context.s2c.length;
+  report->ke_attempts = inst->nke_attempts;
+  if (report->key_length > 0)
+    report->last_ke_ago = SCH_GetLastEventMonoTime() - inst->last_nke_success;
+  else
+    report->last_ke_ago = -1;
+  report->cookies = inst->num_cookies;
+  report->cookie_length = inst->num_cookies > 0 ? inst->cookies[inst->cookie_index].length : 0;
+  report->nak = inst->nak_response;
 }
--- a/nts_ntp_client.h
+++ b/nts_ntp_client.h
@@ -29,11 +29,12 @@

 #include "addressing.h"
 #include "ntp.h"
+#include "reports.h"

 typedef struct NNC_Instance_Record *NNC_Instance;

 extern NNC_Instance NNC_CreateInstance(IPSockAddr *nts_address, const char *name,
-                                                   const IPSockAddr *ntp_address);
+                                       uint32_t cert_set, uint16_t ntp_port);
 extern void NNC_DestroyInstance(NNC_Instance inst);
 extern int NNC_PrepareForAuth(NNC_Instance inst);
 extern int NNC_GenerateRequestAuth(NNC_Instance inst, NTP_Packet *packet,
@@ -43,4 +44,8 @@ extern int NNC_CheckResponseAuth(NNC_Instance inst, NTP_Packet *packet,

 extern void NNC_ChangeAddress(NNC_Instance inst, IPAddr *address);

+extern void NNC_DumpData(NNC_Instance inst);
+
+extern void NNC_GetReport(NNC_Instance inst, RPT_AuthReport *report);
+
 #endif
--- a/nts_ntp_server.c
+++ b/nts_ntp_server.c
@@ -2,7 +2,7 @@
  chronyd/chronyc - Programs for keeping computer clocks accurate.

 **********************************************************************
- * Copyright (C) Miroslav Lichvar  2020
+ * Copyright (C) Miroslav Lichvar  2020, 2022
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
@@ -41,11 +41,15 @@
 #include "siv.h"
 #include "util.h"

+#define MAX_SERVER_SIVS 2
+
 struct NtsServer {
-  SIV_Instance siv;
+  SIV_Instance sivs[MAX_SERVER_SIVS];
+  SIV_Algorithm siv_algorithms[MAX_SERVER_SIVS];
  unsigned char nonce[NTS_MIN_UNPADDED_NONCE_LENGTH];
  NKE_Cookie cookies[NTS_MAX_COOKIES];
  int num_cookies;
+  int siv_index;
  NTP_int64 req_tx;
 };

@@ -57,14 +61,27 @@ struct NtsServer *server;
 void
 NNS_Initialise(void)
 {
+  const char **certs, **keys;
+  int i;
+
  /* Create an NTS-NTP server instance only if NTS-KE server is enabled */
-  if (!CNF_GetNtsServerCertFile() || !CNF_GetNtsServerKeyFile()) {
+  if (CNF_GetNtsServerCertAndKeyFiles(&certs, &keys) <= 0) {
    server = NULL;
    return;
  }

  server = Malloc(sizeof (struct NtsServer));
-  server->siv = SIV_CreateInstance(AEAD_AES_SIV_CMAC_256);
+
+  server->siv_algorithms[0] = AEAD_AES_SIV_CMAC_256;
+  server->siv_algorithms[1] = AEAD_AES_128_GCM_SIV;
+  assert(MAX_SERVER_SIVS == 2);
+
+  for (i = 0; i < 2; i++)
+    server->sivs[i] = SIV_CreateInstance(server->siv_algorithms[i]);
+
+  /* AES-SIV-CMAC-256 is required on servers */
+  if (!server->sivs[0])
+    LOG_FATAL("Missing AES-SIV-CMAC-256");
 }

 /* ================================================== */
@@ -72,10 +89,15 @@ NNS_Initialise(void)
 void
 NNS_Finalise(void)
 {
+  int i;
+
  if (!server)
    return;

-  SIV_DestroyInstance(server->siv);
+  for (i = 0; i < MAX_SERVER_SIVS; i++) {
+    if (server->sivs[i])
+      SIV_DestroyInstance(server->sivs[i]);
+  }
  Free(server);
  server = NULL;
 }
@@ -88,16 +110,18 @@ NNS_CheckRequestAuth(NTP_Packet *packet, NTP_PacketInfo *info, uint32_t *kod)
  int ef_type, ef_body_length, ef_length, has_uniq_id = 0, has_auth = 0, has_cookie = 0;
  int i, plaintext_length, parsed, requested_cookies, cookie_length = -1, auth_start = 0;
  unsigned char plaintext[NTP_MAX_EXTENSIONS_LENGTH];
+  NKE_Context context;
  NKE_Cookie cookie;
-  NKE_Key c2s, s2c;
+  SIV_Instance siv;
  void *ef_body;

+  *kod = 0;
+
  if (!server)
    return 0;

-  *kod = 0;
-
  server->num_cookies = 0;
+  server->siv_index = -1;
  server->req_tx = packet->transmit_ts;

  if (info->ext_fields == 0 || info->mode != MODE_CLIENT)
@@ -108,15 +132,18 @@ NNS_CheckRequestAuth(NTP_Packet *packet, NTP_PacketInfo *info, uint32_t *kod)
  for (parsed = NTP_HEADER_LENGTH; parsed < info->length; parsed += ef_length) {
    if (!NEF_ParseField(packet, info->length, parsed,
                        &ef_length, &ef_type, &ef_body, &ef_body_length))
-      break;
+      /* This is not expected as the packet already passed NAU_ParsePacket() */
+      return 0;

    switch (ef_type) {
      case NTP_EF_NTS_UNIQUE_IDENTIFIER:
        has_uniq_id = 1;
        break;
      case NTP_EF_NTS_COOKIE:
-        if (has_cookie || ef_body_length > sizeof (cookie.cookie))
+        if (has_cookie || ef_body_length > sizeof (cookie.cookie)) {
+          DEBUG_LOG("Unexpected cookie/length");
          return 0;
+        }
        cookie.length = ef_body_length;
        memcpy(cookie.cookie, ef_body, ef_body_length);
        has_cookie = 1;
@@ -131,6 +158,11 @@ NNS_CheckRequestAuth(NTP_Packet *packet, NTP_PacketInfo *info, uint32_t *kod)
        cookie_length = ef_body_length;
        break;
      case NTP_EF_NTS_AUTH_AND_EEF:
+        if (parsed + ef_length != info->length) {
+          DEBUG_LOG("Auth not last EF");
+          return 0;
+        }
+
        auth_start = parsed;
        has_auth = 1;
        break;
@@ -144,17 +176,27 @@ NNS_CheckRequestAuth(NTP_Packet *packet, NTP_PacketInfo *info, uint32_t *kod)
    return 0;
  }

-  if (!NKS_DecodeCookie(&cookie, &c2s, &s2c)) {
+  if (!NKS_DecodeCookie(&cookie, &context)) {
    *kod = NTP_KOD_NTS_NAK;
    return 0;
  }

-  if (!SIV_SetKey(server->siv, c2s.key, c2s.length)) {
+  /* Find the SIV instance needed for authentication */
+  for (i = 0; i < MAX_SERVER_SIVS && context.algorithm != server->siv_algorithms[i]; i++)
+    ;
+  if (i == MAX_SERVER_SIVS || !server->sivs[i]) {
+    DEBUG_LOG("Unexpected SIV");
+    return 0;
+  }
+  server->siv_index = i;
+  siv = server->sivs[i];
+
+  if (!SIV_SetKey(siv, context.c2s.key, context.c2s.length)) {
    DEBUG_LOG("Could not set C2S key");
    return 0;
  }

-  if (!NNA_DecryptAuthEF(packet, info, server->siv, auth_start,
+  if (!NNA_DecryptAuthEF(packet, info, siv, auth_start,
                         plaintext, sizeof (plaintext), &plaintext_length)) {
    *kod = NTP_KOD_NTS_NAK;
    return 0;
@@ -162,8 +204,10 @@ NNS_CheckRequestAuth(NTP_Packet *packet, NTP_PacketInfo *info, uint32_t *kod)

  for (parsed = 0; parsed < plaintext_length; parsed += ef_length) {
    if (!NEF_ParseSingleField(plaintext, plaintext_length, parsed,
-                              &ef_length, &ef_type, &ef_body, &ef_body_length))
-      break;
+                              &ef_length, &ef_type, &ef_body, &ef_body_length)) {
+      DEBUG_LOG("Could not parse encrypted EF");
+      return 0;
+    }

    switch (ef_type) {
      case NTP_EF_NTS_COOKIE_PLACEHOLDER:
@@ -178,18 +222,23 @@ NNS_CheckRequestAuth(NTP_Packet *packet, NTP_PacketInfo *info, uint32_t *kod)
    }
  }

-  if (!SIV_SetKey(server->siv, s2c.key, s2c.length)) {
+  if (!SIV_SetKey(siv, context.s2c.key, context.s2c.length)) {
    DEBUG_LOG("Could not set S2C key");
    return 0;
  }

+  /* Prepare data for NNS_GenerateResponseAuth() to minimise the time spent
+     there (when the TX timestamp is already set) */
+
  UTI_GetRandomBytes(server->nonce, sizeof (server->nonce));

-  server->num_cookies = MIN(NTS_MAX_COOKIES, requested_cookies);
-  for (i = 0; i < server->num_cookies; i++)
-    if (!NKS_GenerateCookie(&c2s, &s2c, &server->cookies[i]))
+  assert(sizeof (server->cookies) / sizeof (server->cookies[0]) == NTS_MAX_COOKIES);
+  for (i = 0; i < NTS_MAX_COOKIES && i < requested_cookies; i++)
+    if (!NKS_GenerateCookie(&context, &server->cookies[i]))
      return 0;

+  server->num_cookies = i;
+
  return 1;
 }

@@ -208,14 +257,16 @@ NNS_GenerateResponseAuth(NTP_Packet *request, NTP_PacketInfo *req_info,
  if (!server || req_info->mode != MODE_CLIENT || res_info->mode != MODE_SERVER)
    return 0;

-  /* Make sure this is a response to the expected request */
+  /* Make sure this is a response to the request from the last call
+     of NNS_CheckRequestAuth() */
  if (UTI_CompareNtp64(&server->req_tx, &request->transmit_ts) != 0)
    assert(0);

  for (parsed = NTP_HEADER_LENGTH; parsed < req_info->length; parsed += ef_length) {
    if (!NEF_ParseField(request, req_info->length, parsed,
                        &ef_length, &ef_type, &ef_body, &ef_body_length))
-      break;
+      /* This is not expected as the packet already passed parsing */
+      return 0;

    switch (ef_type) {
      case NTP_EF_NTS_UNIQUE_IDENTIFIER:
@@ -233,7 +284,7 @@ NNS_GenerateResponseAuth(NTP_Packet *request, NTP_PacketInfo *req_info,

  for (i = 0, plaintext_length = 0; i < server->num_cookies; i++) {
    if (!NEF_SetField(plaintext, sizeof (plaintext), plaintext_length,
-                      NTP_EF_NTS_COOKIE, &server->cookies[i].cookie,
+                      NTP_EF_NTS_COOKIE, server->cookies[i].cookie,
                      server->cookies[i].length, &ef_length))
      return 0;

@@ -243,7 +294,12 @@ NNS_GenerateResponseAuth(NTP_Packet *request, NTP_PacketInfo *req_info,

  server->num_cookies = 0;

-  if (!NNA_GenerateAuthEF(response, res_info, server->siv,
+  if (server->siv_index < 0)
+    return 0;
+
+  /* Generate an authenticator field which will make the length
+     of the response equal to the length of the request */
+  if (!NNA_GenerateAuthEF(response, res_info, server->sivs[server->siv_index],
                          server->nonce, sizeof (server->nonce),
                          plaintext, plaintext_length,
                          req_info->length - res_info->length))
--- a/pktlength.c
+++ b/pktlength.c
@@ -87,7 +87,7 @@ static const struct request_length request_lengths[] = {
  REQ_LENGTH_ENTRY(del_source, null),           /* DEL_SOURCE */
  REQ_LENGTH_ENTRY(null, null),                 /* WRITERTC */
  REQ_LENGTH_ENTRY(dfreq, null),                /* DFREQ */
-  REQ_LENGTH_ENTRY(doffset, null),              /* DOFFSET */
+  { 0, 0 },                                     /* DOFFSET - not supported */
  REQ_LENGTH_ENTRY(null, tracking),             /* TRACKING */
  REQ_LENGTH_ENTRY(sourcestats, sourcestats),   /* SOURCESTATS */
  REQ_LENGTH_ENTRY(null, rtc),                  /* RTCREPORT */
@@ -110,8 +110,7 @@ static const struct request_length request_lengths[] = {
  REQ_LENGTH_ENTRY(smoothtime, null),           /* SMOOTHTIME */
  REQ_LENGTH_ENTRY(null, null),                 /* REFRESH */
  REQ_LENGTH_ENTRY(null, server_stats),         /* SERVER_STATS */
-  REQ_LENGTH_ENTRY(client_accesses_by_index,
-                   client_accesses_by_index),   /* CLIENT_ACCESSES_BY_INDEX2 */
+  { 0, 0 },                                     /* CLIENT_ACCESSES_BY_INDEX2 - not supported */
  REQ_LENGTH_ENTRY(local, null),                /* LOCAL2 */
  REQ_LENGTH_ENTRY(ntp_data, ntp_data),         /* NTP_DATA */
  { 0, 0 },                                     /* ADD_SERVER2 */
@@ -123,7 +122,14 @@ static const struct request_length request_lengths[] = {
  REQ_LENGTH_ENTRY(ntp_source, null),           /* ADD_SOURCE */
  REQ_LENGTH_ENTRY(ntp_source_name,
                   ntp_source_name),            /* NTP_SOURCE_NAME */
-  REQ_LENGTH_ENTRY(null, null),                 /* RESET */
+  REQ_LENGTH_ENTRY(null, null),                 /* RESET_SOURCES */
+  REQ_LENGTH_ENTRY(auth_data, auth_data),       /* AUTH_DATA */
+  REQ_LENGTH_ENTRY(client_accesses_by_index,
+                   client_accesses_by_index),   /* CLIENT_ACCESSES_BY_INDEX3 */
+  REQ_LENGTH_ENTRY(select_data, select_data),   /* SELECT_DATA */
+  REQ_LENGTH_ENTRY(null, null),                 /* RELOAD_SOURCES */
+  REQ_LENGTH_ENTRY(doffset, null),              /* DOFFSET2 */
+  REQ_LENGTH_ENTRY(modify_select_opts, null),   /* MODIFY_SELECTOPTS */
 };

 static const uint16_t reply_lengths[] = {
@@ -141,12 +147,18 @@ static const uint16_t reply_lengths[] = {
  0,                                            /* MANUAL_LIST - not supported */
  RPY_LENGTH_ENTRY(activity),                   /* ACTIVITY */
  RPY_LENGTH_ENTRY(smoothing),                  /* SMOOTHING */
-  RPY_LENGTH_ENTRY(server_stats),               /* SERVER_STATS */
-  RPY_LENGTH_ENTRY(client_accesses_by_index),   /* CLIENT_ACCESSES_BY_INDEX2 */
+  0,                                            /* SERVER_STATS - not supported */
+  0,                                            /* CLIENT_ACCESSES_BY_INDEX2 - not supported */
  RPY_LENGTH_ENTRY(ntp_data),                   /* NTP_DATA */
  RPY_LENGTH_ENTRY(manual_timestamp),           /* MANUAL_TIMESTAMP2 */
  RPY_LENGTH_ENTRY(manual_list),                /* MANUAL_LIST2 */
  RPY_LENGTH_ENTRY(ntp_source_name),            /* NTP_SOURCE_NAME */
+  RPY_LENGTH_ENTRY(auth_data),                  /* AUTH_DATA */
+  RPY_LENGTH_ENTRY(client_accesses_by_index),   /* CLIENT_ACCESSES_BY_INDEX3 */
+  0,                                            /* SERVER_STATS2 - not supported */
+  RPY_LENGTH_ENTRY(select_data),                /* SELECT_DATA */
+  0,                                            /* SERVER_STATS3 - not supported */
+  RPY_LENGTH_ENTRY(server_stats),               /* SERVER_STATS4 */
 };

 /* ================================================== */
--- a/privops.c
+++ b/privops.c
@@ -171,22 +171,22 @@ send_response(int fd, const PrvResponse *res)
 static int
 receive_from_daemon(int fd, PrvRequest *req)
 {
-  SCK_Message message;
+  SCK_Message *message;

-  if (!SCK_ReceiveMessage(fd, &message, SCK_FLAG_MSG_DESCRIPTOR) ||
-      message.length != sizeof (*req))
+  message = SCK_ReceiveMessage(fd, SCK_FLAG_MSG_DESCRIPTOR);
+  if (!message || message->length != sizeof (*req))
    return 0;

-  memcpy(req, message.data, sizeof (*req));
+  memcpy(req, message->data, sizeof (*req));

  if (req->op == OP_BINDSOCKET) {
-    req->data.bind_socket.sock = message.descriptor;
+    req->data.bind_socket.sock = message->descriptor;

    /* return error if valid descriptor not found */
    if (req->data.bind_socket.sock < 0)
      return 0;
-  } else if (message.descriptor >= 0) {
-    SCK_CloseSocket(message.descriptor);
+  } else if (message->descriptor >= 0) {
+    SCK_CloseSocket(message->descriptor);
    return 0;
  }

@@ -255,7 +255,7 @@ do_bind_socket(ReqBindSocket *req, PrvResponse *res)

  SCK_SockaddrToIPSockAddr(sa, sa_len, &ip_saddr);
  if (ip_saddr.port != 0 && ip_saddr.port != CNF_GetNTPPort() &&
-      ip_saddr.port != CNF_GetAcquisitionPort()) {
+      ip_saddr.port != CNF_GetAcquisitionPort() && ip_saddr.port != CNF_GetPtpPort()) {
    SCK_CloseSocket(sock_fd);
    res_fatal(res, "Invalid port %d", ip_saddr.port);
    return;
@@ -547,7 +547,7 @@ PRV_BindSocket(int sock, struct sockaddr *address, socklen_t address_len)

  SCK_SockaddrToIPSockAddr(address, address_len, &ip_saddr);
  if (ip_saddr.port != 0 && ip_saddr.port != CNF_GetNTPPort() &&
-      ip_saddr.port != CNF_GetAcquisitionPort())
+      ip_saddr.port != CNF_GetAcquisitionPort() && ip_saddr.port != CNF_GetPtpPort())
    assert(0);

  if (!have_helper())
@@ -644,6 +644,8 @@ PRV_StartHelper(void)
    LOG_FATAL("Helper already running");

  sock_fd1 = SCK_OpenUnixSocketPair(SCK_FLAG_BLOCK, &sock_fd2);
+  if (sock_fd1 < 0)
+    LOG_FATAL("Could not open socket pair");

  pid = fork();
  if (pid < 0)
@@ -660,6 +662,8 @@ PRV_StartHelper(void)
        close(fd);
    }

+    UTI_ResetGetRandomFunctions();
+
    /* ignore signals, the process will exit on OP_QUIT request */
    UTI_SetQuitSignalsHandler(SIG_IGN, 1);

--- a/ptp.h
+++ b/ptp.h
@@ -0,0 +1,69 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2021
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  This is the header file for the Precision Time Protocol (PTP).
+
+  */
+#ifndef GOT_PTP_H
+#define GOT_PTP_H
+
+#include "sysincl.h"
+
+#include "ntp.h"
+
+#define PTP_VERSION 2
+#define PTP_TYPE_DELAY_REQ 1
+#define PTP_DOMAIN_NTP 123
+#define PTP_FLAG_UNICAST (1 << (2 + 8))
+#define PTP_TLV_NTP 0x2023
+
+typedef struct {
+  uint8_t type;
+  uint8_t version;
+  uint16_t length;
+  uint8_t domain;
+  uint8_t min_sdoid;
+  uint16_t flags;
+  uint8_t correction[8];
+  uint8_t msg_specific[4];
+  uint8_t port_id[10];
+  uint16_t sequence_id;
+  uint8_t control;
+  int8_t interval;
+} PTP_Header;
+
+typedef struct {
+  uint16_t type;
+  uint16_t length;
+} PTP_TlvHeader;
+
+typedef struct {
+  PTP_Header header;
+  uint8_t origin_ts[10];
+  PTP_TlvHeader tlv_header;
+  NTP_Packet ntp_msg;
+} PTP_NtpMessage;
+
+#define PTP_NTP_PREFIX_LENGTH (int)offsetof(PTP_NtpMessage, ntp_msg)
+
+#endif
--- a/quantiles.c
+++ b/quantiles.c
@@ -0,0 +1,209 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2022
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  Estimation of quantiles using the Frugal-2U streaming algorithm
+  (https://arxiv.org/pdf/1407.1121v1.pdf)
+  */
+
+#include "config.h"
+
+#include "logging.h"
+#include "memory.h"
+#include "quantiles.h"
+#include "regress.h"
+#include "util.h"
+
+/* Maximum number of repeated estimates for stabilisation */
+#define MAX_REPEAT 64
+
+struct Quantile {
+  double est;
+  double step;
+  int sign;
+};
+
+struct QNT_Instance_Record {
+  struct Quantile *quants;
+  int n_quants;
+  int repeat;
+  int q;
+  int min_k;
+  double min_step;
+  int n_set;
+};
+
+/* ================================================== */
+
+QNT_Instance
+QNT_CreateInstance(int min_k, int max_k, int q, int repeat, double min_step)
+{
+  QNT_Instance inst;
+  long seed;
+
+  if (q < 2 || min_k > max_k || min_k < 1 || max_k >= q ||
+      repeat < 1 || repeat > MAX_REPEAT || min_step <= 0.0)
+    assert(0);
+
+  inst = MallocNew(struct QNT_Instance_Record);
+  inst->n_quants = (max_k - min_k + 1) * repeat;
+  inst->quants = MallocArray(struct Quantile, inst->n_quants);
+  inst->repeat = repeat;
+  inst->q = q;
+  inst->min_k = min_k;
+  inst->min_step = min_step;
+
+  QNT_Reset(inst);
+
+  /* Seed the random number generator, which will not be isolated from
+     other instances and other random() users */
+  UTI_GetRandomBytes(&seed, sizeof (seed));
+  srandom(seed);
+
+  return inst;
+}
+
+/* ================================================== */
+
+void
+QNT_DestroyInstance(QNT_Instance inst)
+{
+  Free(inst->quants);
+  Free(inst);
+}
+
+/* ================================================== */
+
+void
+QNT_Reset(QNT_Instance inst)
+{
+  int i;
+
+  inst->n_set = 0;
+
+  for (i = 0; i < inst->n_quants; i++) {
+    inst->quants[i].est = 0.0;
+    inst->quants[i].step = inst->min_step;
+    inst->quants[i].sign = 1;
+  }
+}
+
+/* ================================================== */
+
+static void
+insert_initial_value(QNT_Instance inst, double value)
+{
+  int i, j, r = inst->repeat;
+
+  if (inst->n_set * r >= inst->n_quants)
+    assert(0);
+
+  /* Keep the initial estimates repeated and ordered */
+  for (i = inst->n_set; i > 0 && inst->quants[(i - 1) * r].est > value; i--) {
+    for (j = 0; j < r; j++)
+      inst->quants[i * r + j].est = inst->quants[(i - 1) * r].est;
+  }
+
+  for (j = 0; j < r; j++)
+    inst->quants[i * r + j].est = value;
+  inst->n_set++;
+
+  /* Duplicate the largest value in unset quantiles */
+  for (i = inst->n_set * r; i < inst->n_quants; i++)
+    inst->quants[i].est = inst->quants[i - 1].est;
+}
+
+/* ================================================== */
+
+static void
+update_estimate(struct Quantile *quantile, double value, double p, double rand,
+                double min_step)
+{
+  if (value > quantile->est && rand > (1.0 - p)) {
+    quantile->step += quantile->sign > 0 ? min_step : -min_step;
+    quantile->est += quantile->step > 0.0 ? fabs(quantile->step) : min_step;
+    if (quantile->est > value) {
+      quantile->step += value - quantile->est;
+      quantile->est = value;
+    }
+    if (quantile->sign < 0 && quantile->step > min_step)
+      quantile->step = min_step;
+    quantile->sign = 1;
+  } else if (value < quantile->est && rand > p) {
+    quantile->step += quantile->sign < 0 ? min_step : -min_step;
+    quantile->est -= quantile->step > 0.0 ? fabs(quantile->step) : min_step;
+    if (quantile->est < value) {
+      quantile->step += quantile->est - value;
+      quantile->est = value;
+    }
+    if (quantile->sign > 0 && quantile->step > min_step)
+      quantile->step = min_step;
+    quantile->sign = -1;
+  }
+}
+
+/* ================================================== */
+
+void
+QNT_Accumulate(QNT_Instance inst, double value)
+{
+  double p, rand;
+  int i;
+
+  /* Initialise the estimates with first received values */
+  if (inst->n_set * inst->repeat < inst->n_quants) {
+    insert_initial_value(inst, value);
+    return;
+  }
+
+  for (i = 0; i < inst->n_quants; i++) {
+    p = (double)(i / inst->repeat + inst->min_k) / inst->q;
+    rand = (double)random() / ((1U << 31) - 1);
+
+    update_estimate(&inst->quants[i], value, p, rand, inst->min_step);
+  }
+}
+
+/* ================================================== */
+
+int
+QNT_GetMinK(QNT_Instance inst)
+{
+  return inst->min_k;
+}
+
+/* ================================================== */
+
+double
+QNT_GetQuantile(QNT_Instance inst, int k)
+{
+  double estimates[MAX_REPEAT];
+  int i;
+
+  if (k < inst->min_k || k - inst->min_k >= inst->n_quants)
+    assert(0);
+
+  for (i = 0; i < inst->repeat; i++)
+    estimates[i] = inst->quants[(k - inst->min_k) * inst->repeat + i].est;
+
+  return RGR_FindMedian(estimates, inst->repeat);
+}
--- a/quantiles.h
+++ b/quantiles.h
@@ -0,0 +1,41 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2022
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for estimation of quantiles.
+
+  */
+
+#ifndef GOT_QUANTILES_H
+#define GOT_QUANTILES_H
+
+typedef struct QNT_Instance_Record *QNT_Instance;
+
+extern QNT_Instance QNT_CreateInstance(int min_k, int max_k, int q, int repeat, double min_step);
+extern void QNT_DestroyInstance(QNT_Instance inst);
+
+extern void QNT_Reset(QNT_Instance inst);
+extern void QNT_Accumulate(QNT_Instance inst, double value);
+extern int QNT_GetMinK(QNT_Instance inst);
+extern double QNT_GetQuantile(QNT_Instance inst, int k);
+
+#endif
--- a/refclock.c
+++ b/refclock.c
@@ -2,7 +2,7 @@
  chronyd/chronyc - Programs for keeping computer clocks accurate.

 **********************************************************************
- * Copyright (C) Miroslav Lichvar  2009-2011, 2013-2014, 2016-2019
+ * Copyright (C) Miroslav Lichvar  2009-2011, 2013-2014, 2016-2019, 2022
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
@@ -40,6 +40,9 @@
 #include "samplefilt.h"
 #include "sched.h"

+/* Maximum offset of locked reference as a fraction of the PPS interval */
+#define PPS_LOCK_LIMIT 0.4
+
 /* list of refclock drivers */
 extern RefclockDriver RCL_SHM_driver;
 extern RefclockDriver RCL_SOCK_driver;
@@ -52,21 +55,6 @@ struct FilterSample {
  struct timespec sample_time;
 };

-struct MedianFilter {
-  int length;
-  int index;
-  int used;
-  int last;
-  int avg_var_n;
-  double avg_var;
-  double max_var;
-  struct FilterSample *samples;
-  int *selected;
-  double *x_data;
-  double *y_data;
-  double *w_data;
-};
-
 struct RCL_Instance_Record {
  RefclockDriver *driver;
  void *data;
@@ -76,6 +64,7 @@ struct RCL_Instance_Record {
  int driver_polled;
  int poll;
  int leap_status;
+  int local;
  int pps_forced;
  int pps_rate;
  int pps_active;
@@ -181,12 +170,13 @@ RCL_AddRefclock(RefclockParameters *params)
    LOG_FATAL("refclock tai option requires leapsectz");

  inst->data = NULL;
-  inst->driver_parameter = params->driver_parameter;
+  inst->driver_parameter = Strdup(params->driver_parameter);
  inst->driver_parameter_length = 0;
  inst->driver_poll = params->driver_poll;
  inst->poll = params->poll;
  inst->driver_polled = 0;
  inst->leap_status = LEAP_Normal;
+  inst->local = params->local;
  inst->pps_forced = params->pps_forced;
  inst->pps_rate = params->pps_rate;
  inst->pps_active = 0;
@@ -228,6 +218,13 @@ RCL_AddRefclock(RefclockParameters *params)
    inst->ref_id = (uint32_t)ref[0] << 24 | ref[1] << 16 | ref[2] << 8 | ref[3];
  }

+  if (inst->local) {
+    inst->pps_forced = 1;
+    inst->lock_ref = inst->ref_id;
+    inst->leap_status = LEAP_Unsynchronised;
+    inst->max_lock_age = MAX(inst->max_lock_age, 3);
+  }
+
  if (inst->driver->poll) {
    int max_samples;

@@ -253,22 +250,21 @@ RCL_AddRefclock(RefclockParameters *params)
  inst->filter = SPF_CreateInstance(MIN(params->filter_length, 4), params->filter_length,
                                    params->max_dispersion, 0.6);

-  inst->source = SRC_CreateNewInstance(inst->ref_id, SRC_REFCLOCK, params->sel_options, NULL,
-                                       params->min_samples, params->max_samples, 0.0, 0.0);
+  inst->source = SRC_CreateNewInstance(inst->ref_id, SRC_REFCLOCK, 0, params->sel_options,
+                                       NULL, params->min_samples, params->max_samples,
+                                       0.0, 0.0);

  DEBUG_LOG("refclock %s refid=%s poll=%d dpoll=%d filter=%d",
      params->driver_name, UTI_RefidToString(inst->ref_id),
      inst->poll, inst->driver_poll, params->filter_length);

-  Free(params->driver_name);
-
  return 1;
 }

 void
 RCL_StartRefclocks(void)
 {
-  unsigned int i, j, n;
+  unsigned int i, j, n, lock_index;

  n = ARR_GetSize(refclocks);

@@ -278,13 +274,31 @@ RCL_StartRefclocks(void)
    SRC_SetActive(inst->source);
    inst->timeout_id = SCH_AddTimeoutByDelay(0.0, poll_timeout, (void *)inst);

-    if (inst->lock_ref) {
-      /* Replace lock refid with index to refclocks */
-      for (j = 0; j < n && get_refclock(j)->ref_id != inst->lock_ref; j++)
-        ;
-      inst->lock_ref = j < n ? j : -1;
-    } else
-      inst->lock_ref = -1;
+    /* Replace lock refid with the refclock's index, or -1 if not valid */
+
+    lock_index = -1;
+
+    if (inst->lock_ref != 0) {
+      for (j = 0; j < n; j++) {
+        RCL_Instance inst2 = get_refclock(j);
+
+        if (inst->lock_ref != inst2->ref_id)
+          continue;
+
+        if (inst->driver->poll && inst2->driver->poll &&
+            (double)inst->max_lock_age / inst->pps_rate < UTI_Log2ToDouble(inst2->driver_poll))
+          LOG(LOGS_WARN, "%s maxlockage too small for %s",
+              UTI_RefidToString(inst->ref_id), UTI_RefidToString(inst2->ref_id));
+
+        lock_index = j;
+        break;
+      }
+
+      if (lock_index == -1 || (lock_index == i && !inst->local))
+        LOG(LOGS_WARN, "Invalid lock refid %s", UTI_RefidToString(inst->lock_ref));
+    }
+
+    inst->lock_ref = lock_index;
  }
 }

@@ -416,30 +430,28 @@ accumulate_sample(RCL_Instance instance, struct timespec *sample_time, double of
  sample.peer_dispersion = dispersion;
  sample.root_dispersion = dispersion;

-  /* Handle special case when PPS is used with the local reference */
-  if (instance->pps_active && instance->lock_ref == -1)
-    sample.stratum = pps_stratum(instance, &sample.time);
-  else
-    sample.stratum = instance->stratum;
-
  return SPF_AccumulateSample(instance->filter, &sample);
 }

 int
-RCL_AddSample(RCL_Instance instance, struct timespec *sample_time, double offset, int leap)
+RCL_AddSample(RCL_Instance instance, struct timespec *sample_time,
+              struct timespec *ref_time, int leap)
 {
-  double correction, dispersion;
+  double correction, dispersion, raw_offset, offset;
  struct timespec cooked_time;

  if (instance->pps_forced)
-    return RCL_AddPulse(instance, sample_time, -offset);
+    return RCL_AddPulse(instance, sample_time,
+                        1.0e-9 * (sample_time->tv_nsec - ref_time->tv_nsec));
+
+  raw_offset = UTI_DiffTimespecsToDouble(ref_time, sample_time);

  LCL_GetOffsetCorrection(sample_time, &correction, &dispersion);
  UTI_AddDoubleToTimespec(sample_time, correction, &cooked_time);
  dispersion += instance->precision;

  /* Make sure the timestamp and offset provided by the driver are sane */
-  if (!UTI_IsTimeOffsetSane(sample_time, offset) ||
+  if (!UTI_IsTimeOffsetSane(sample_time, raw_offset) ||
      !valid_sample_time(instance, &cooked_time))
    return 0;

@@ -454,18 +466,24 @@ RCL_AddSample(RCL_Instance instance, struct timespec *sample_time, double offset
      return 0;
  }

+  /* Calculate offset = raw_offset - correction + instance->offset
+     in parts to avoid loss of precision if there are large differences */
+  offset = ref_time->tv_sec - sample_time->tv_sec -
+           (time_t)correction + (time_t)instance->offset;
+  offset += 1.0e-9 * (ref_time->tv_nsec - sample_time->tv_nsec) -
+            (correction - (time_t)correction) + (instance->offset - (time_t)instance->offset);
+
  if (instance->tai && !convert_tai_offset(sample_time, &offset)) {
    DEBUG_LOG("refclock sample ignored unknown TAI offset");
    return 0;
  }

-  if (!accumulate_sample(instance, &cooked_time,
-                         offset - correction + instance->offset, dispersion))
+  if (!accumulate_sample(instance, &cooked_time, offset, dispersion))
    return 0;

  instance->pps_active = 0;

-  log_sample(instance, &cooked_time, 0, 0, offset, offset - correction + instance->offset, dispersion);
+  log_sample(instance, &cooked_time, 0, 0, raw_offset, offset, dispersion);

  /* for logging purposes */
  if (!instance->driver->poll)
@@ -544,29 +562,40 @@ RCL_AddCookedPulse(RCL_Instance instance, struct timespec *cooked_time,
    lock_refclock = get_refclock(instance->lock_ref);

    if (!SPF_GetLastSample(lock_refclock->filter, &ref_sample)) {
-      DEBUG_LOG("refclock pulse ignored no ref sample");
-      return 0;
+      if (instance->local) {
+        /* Make the first sample in order to lock to itself */
+        ref_sample.time = *cooked_time;
+        ref_sample.offset = offset;
+        ref_sample.peer_delay = ref_sample.peer_dispersion = 0;
+        ref_sample.root_delay = ref_sample.root_dispersion = 0;
+      } else {
+        DEBUG_LOG("refclock pulse ignored no ref sample");
+        return 0;
+      }
    }

    ref_sample.root_dispersion += SPF_GetAvgSampleDispersion(lock_refclock->filter);

    sample_diff = UTI_DiffTimespecsToDouble(cooked_time, &ref_sample.time);
    if (fabs(sample_diff) >= (double)instance->max_lock_age / rate) {
-      DEBUG_LOG("refclock pulse ignored samplediff=%.9f",
-          sample_diff);
+      DEBUG_LOG("refclock pulse ignored samplediff=%.9f", sample_diff);
+
+      /* Restart the local mode */
+      if (instance->local) {
+        LOG(LOGS_WARN, "Local refclock lost lock");
+        SPF_DropSamples(instance->filter);
+        SRC_ResetInstance(instance->source);
+      }
      return 0;
    }

    /* Align the offset to the reference sample */
-    if ((ref_sample.offset - offset) >= 0.0)
-      shift = (long)((ref_sample.offset - offset) * rate + 0.5) / (double)rate;
-    else
-      shift = (long)((ref_sample.offset - offset) * rate - 0.5) / (double)rate;
+    shift = round((ref_sample.offset - offset) * rate) / rate;

    offset += shift;

    if (fabs(ref_sample.offset - offset) +
-        ref_sample.root_dispersion + dispersion >= 0.2 / rate) {
+        ref_sample.root_dispersion + dispersion > PPS_LOCK_LIMIT / rate) {
      DEBUG_LOG("refclock pulse ignored offdiff=%.9f refdisp=%.9f disp=%.9f",
                ref_sample.offset - offset, ref_sample.root_dispersion, dispersion);
      return 0;
@@ -682,11 +711,57 @@ pps_stratum(RCL_Instance instance, struct timespec *ts)
  return 0;
 }

+static void
+get_local_stats(RCL_Instance inst, struct timespec *ref, double *freq, double *offset)
+{
+  double offset_sd, freq_sd, skew, root_delay, root_disp;
+  SST_Stats stats = SRC_GetSourcestats(inst->source);
+
+  if (SST_Samples(stats) < SST_GetMinSamples(stats)) {
+    UTI_ZeroTimespec(ref);
+    return;
+  }
+
+  SST_GetTrackingData(stats, ref, offset, &offset_sd, freq, &freq_sd,
+                      &skew, &root_delay, &root_disp);
+}
+
+static void
+follow_local(RCL_Instance inst, struct timespec *prev_ref_time, double prev_freq,
+             double prev_offset)
+{
+  SST_Stats stats = SRC_GetSourcestats(inst->source);
+  double freq, dfreq, offset, doffset, elapsed;
+  struct timespec now, ref_time;
+
+  get_local_stats(inst, &ref_time, &freq, &offset);
+
+  if (UTI_IsZeroTimespec(prev_ref_time) || UTI_IsZeroTimespec(&ref_time))
+    return;
+
+  dfreq = (freq - prev_freq) / (1.0 - prev_freq);
+  elapsed = UTI_DiffTimespecsToDouble(&ref_time, prev_ref_time);
+  doffset = offset - elapsed * prev_freq - prev_offset;
+
+  if (!REF_AdjustReference(doffset, dfreq))
+    return;
+
+  LCL_ReadCookedTime(&now, NULL);
+  SST_SlewSamples(stats, &now, dfreq, doffset);
+  SPF_SlewSamples(inst->filter, &now, dfreq, doffset);
+
+  /* Keep the offset close to zero to not lose precision */
+  if (fabs(offset) >= 1.0) {
+    SST_CorrectOffset(stats, -round(offset));
+    SPF_CorrectOffset(inst->filter, -round(offset));
+  }
+}
+
 static void
 poll_timeout(void *arg)
 {
  NTP_Sample sample;
-  int poll;
+  int poll, stratum;

  RCL_Instance inst = (RCL_Instance)arg;

@@ -702,11 +777,28 @@ poll_timeout(void *arg)
    inst->driver_polled = 0;

    if (SPF_GetFilteredSample(inst->filter, &sample)) {
+      double local_freq, local_offset;
+      struct timespec local_ref_time;
+
+      /* Handle special case when PPS is used with the local reference */
+      if (inst->pps_active && inst->lock_ref == -1)
+        stratum = pps_stratum(inst, &sample.time);
+      else
+        stratum = inst->stratum;
+
+      if (inst->local) {
+        get_local_stats(inst, &local_ref_time, &local_freq, &local_offset);
+        inst->leap_status = LEAP_Unsynchronised;
+      }
+
      SRC_UpdateReachability(inst->source, 1);
-      SRC_SetLeapStatus(inst->source, inst->leap_status);
+      SRC_UpdateStatus(inst->source, stratum, inst->leap_status);
      SRC_AccumulateSample(inst->source, &sample);
      SRC_SelectSource(inst->source);

+      if (inst->local)
+        follow_local(inst, &local_ref_time, local_freq, local_offset);
+
      log_sample(inst, &sample.time, 1, 0, 0.0, sample.offset, sample.peer_dispersion);
    } else {
      SRC_UpdateReachability(inst->source, 0);
--- a/refclock.h
+++ b/refclock.h
@@ -37,6 +37,7 @@ typedef struct {
  int driver_poll;
  int poll;
  int filter_length;
+  int local;
  int pps_forced;
  int pps_rate;
  int min_samples;
@@ -74,7 +75,8 @@ extern void *RCL_GetDriverData(RCL_Instance instance);
 extern char *RCL_GetDriverParameter(RCL_Instance instance);
 extern void RCL_CheckDriverOptions(RCL_Instance instance, const char **options);
 extern char *RCL_GetDriverOption(RCL_Instance instance, char *name);
-extern int RCL_AddSample(RCL_Instance instance, struct timespec *sample_time, double offset, int leap);
+extern int RCL_AddSample(RCL_Instance instance, struct timespec *sample_time,
+                         struct timespec *ref_time, int leap);
 extern int RCL_AddPulse(RCL_Instance instance, struct timespec *pulse_time, double second);
 extern int RCL_AddCookedPulse(RCL_Instance instance, struct timespec *cooked_time,
                              double second, double dispersion, double raw_correction);
--- a/refclock_phc.c
+++ b/refclock_phc.c
@@ -2,7 +2,7 @@
  chronyd/chronyc - Programs for keeping computer clocks accurate.

 **********************************************************************
- * Copyright (C) Miroslav Lichvar  2013, 2017
+ * Copyright (C) Miroslav Lichvar  2013, 2017, 2023
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
@@ -33,6 +33,9 @@

 #include "sysincl.h"

+#include <sys/sysmacros.h>
+
+#include "array.h"
 #include "refclock.h"
 #include "hwclock.h"
 #include "local.h"
@@ -44,14 +47,19 @@

 struct phc_instance {
  int fd;
+  int dev_index;
  int mode;
  int nocrossts;
  int extpps;
  int pin;
  int channel;
+  struct timespec last_extts;
  HCL_Instance clock;
 };

+/* Array of RCL_Instance with enabled extpps */
+static ARR_Instance extts_phcs = NULL;
+
 static void read_ext_pulse(int sockfd, int event, void *anything);

 static int phc_initialise(RCL_Instance instance)
@@ -59,6 +67,7 @@ static int phc_initialise(RCL_Instance instance)
  const char *options[] = {"nocrossts", "extpps", "pin", "channel", "clear", NULL};
  struct phc_instance *phc;
  int phc_fd, rising_edge;
+  struct stat st;
  char *path, *s;

  RCL_CheckDriverOptions(instance, options);
@@ -66,16 +75,20 @@ static int phc_initialise(RCL_Instance instance)
  path = RCL_GetDriverParameter(instance);
 
  phc_fd = SYS_Linux_OpenPHC(path, 0);
-  if (phc_fd < 0) {
+  if (phc_fd < 0)
    LOG_FATAL("Could not open PHC");
-    return 0;
-  }

  phc = MallocNew(struct phc_instance);
  phc->fd = phc_fd;
+  if (fstat(phc_fd, &st) < 0 || !S_ISCHR(st.st_mode))
+    LOG_FATAL("Could not get PHC index");
+  phc->dev_index = minor(st.st_rdev);
  phc->mode = 0;
  phc->nocrossts = RCL_GetDriverOption(instance, "nocrossts") ? 1 : 0;
  phc->extpps = RCL_GetDriverOption(instance, "extpps") ? 1 : 0;
+  UTI_ZeroTimespec(&phc->last_extts);
+  phc->clock = HCL_CreateInstance(0, 16, UTI_Log2ToDouble(RCL_GetDriverPoll(instance)),
+                                  RCL_GetPrecision(instance));

  if (phc->extpps) {
    s = RCL_GetDriverOption(instance, "pin");
@@ -83,16 +96,18 @@ static int phc_initialise(RCL_Instance instance)
    s = RCL_GetDriverOption(instance, "channel");
    phc->channel = s ? atoi(s) : 0;
    rising_edge = RCL_GetDriverOption(instance, "clear") ? 0 : 1;
-    phc->clock = HCL_CreateInstance(0, 16, UTI_Log2ToDouble(RCL_GetDriverPoll(instance)));

    if (!SYS_Linux_SetPHCExtTimestamping(phc->fd, phc->pin, phc->channel,
                                         rising_edge, !rising_edge, 1))
      LOG_FATAL("Could not enable external PHC timestamping");

    SCH_AddFileHandler(phc->fd, SCH_FILE_INPUT, read_ext_pulse, instance);
+
+    if (!extts_phcs)
+      extts_phcs = ARR_CreateInstance(sizeof (RCL_Instance));
+    ARR_AppendElement(extts_phcs, &instance);
  } else {
    phc->pin = phc->channel = 0;
-    phc->clock = NULL;
  }

  RCL_SetDriverData(instance, phc);
@@ -102,68 +117,106 @@ static int phc_initialise(RCL_Instance instance)
 static void phc_finalise(RCL_Instance instance)
 {
  struct phc_instance *phc;
+  unsigned int i;

  phc = (struct phc_instance *)RCL_GetDriverData(instance);

  if (phc->extpps) {
    SCH_RemoveFileHandler(phc->fd);
    SYS_Linux_SetPHCExtTimestamping(phc->fd, phc->pin, phc->channel, 0, 0, 0);
-    HCL_DestroyInstance(phc->clock);
+
+    for (i = 0; i < ARR_GetSize(extts_phcs); i++) {
+      if ((*(RCL_Instance *)ARR_GetElement(extts_phcs, i)) == instance)
+        ARR_RemoveElement(extts_phcs, i--);
+    }
+    if (ARR_GetSize(extts_phcs) == 0) {
+      ARR_DestroyInstance(extts_phcs);
+      extts_phcs = NULL;
+    }
  }

+  HCL_DestroyInstance(phc->clock);
  close(phc->fd);
  Free(phc);
 }

+static void process_ext_pulse(RCL_Instance instance, struct timespec *phc_ts)
+{
+  struct phc_instance *phc;
+  struct timespec local_ts;
+  double local_err;
+
+  phc = RCL_GetDriverData(instance);
+
+  if (UTI_CompareTimespecs(&phc->last_extts, phc_ts) == 0) {
+    DEBUG_LOG("Ignoring duplicated PHC timestamp");
+    return;
+  }
+  phc->last_extts = *phc_ts;
+
+  if (!HCL_CookTime(phc->clock, phc_ts, &local_ts, &local_err))
+    return;
+
+  RCL_AddCookedPulse(instance, &local_ts, 1.0e-9 * local_ts.tv_nsec, local_err,
+                     UTI_DiffTimespecsToDouble(phc_ts, &local_ts));
+}
+
 static void read_ext_pulse(int fd, int event, void *anything)
 {
  RCL_Instance instance;
-  struct phc_instance *phc;
-  struct timespec phc_ts, local_ts;
-  double local_err;
+  struct phc_instance *phc1, *phc2;
+  struct timespec phc_ts;
+  unsigned int i;
  int channel;

+  if (!SYS_Linux_ReadPHCExtTimestamp(fd, &phc_ts, &channel))
+    return;
+
  instance = anything;
-  phc = RCL_GetDriverData(instance);
+  phc1 = RCL_GetDriverData(instance);

-  if (!SYS_Linux_ReadPHCExtTimestamp(phc->fd, &phc_ts, &channel))
-    return;
+  /* The Linux kernel (as of 6.2) has one shared queue of timestamps for all
+     descriptors of the same PHC.  Search for all refclocks that expect
+     the timestamp. */

-  if (channel != phc->channel) {
-    DEBUG_LOG("Unexpected extts channel %d\n", channel);
-    return;
+  for (i = 0; i < ARR_GetSize(extts_phcs); i++) {
+    instance = *(RCL_Instance *)ARR_GetElement(extts_phcs, i);
+    phc2 = RCL_GetDriverData(instance);
+    if (!phc2->extpps || phc2->dev_index != phc1->dev_index || phc2->channel != channel)
+      continue;
+    process_ext_pulse(instance, &phc_ts);
  }
-
-  if (!HCL_CookTime(phc->clock, &phc_ts, &local_ts, &local_err))
-    return;
-
-  RCL_AddCookedPulse(instance, &local_ts, 1.0e-9 * local_ts.tv_nsec, local_err,
-                     UTI_DiffTimespecsToDouble(&phc_ts, &local_ts));
 }

+#define PHC_READINGS 25
+
 static int phc_poll(RCL_Instance instance)
 {
+  struct timespec phc_ts, sys_ts, local_ts, readings[PHC_READINGS][3];
  struct phc_instance *phc;
-  struct timespec phc_ts, sys_ts, local_ts;
-  double offset, phc_err, local_err;
+  double phc_err, local_err;
+  int n_readings;

  phc = (struct phc_instance *)RCL_GetDriverData(instance);

-  if (!SYS_Linux_GetPHCSample(phc->fd, phc->nocrossts, RCL_GetPrecision(instance),
-                              &phc->mode, &phc_ts, &sys_ts, &phc_err))
+  n_readings = SYS_Linux_GetPHCReadings(phc->fd, phc->nocrossts, &phc->mode,
+                                        PHC_READINGS, readings);
+  if (n_readings < 1)
    return 0;

-  if (phc->extpps) {
-    LCL_CookTime(&sys_ts, &local_ts, &local_err);
-    HCL_AccumulateSample(phc->clock, &phc_ts, &local_ts, phc_err + local_err);
+  if (!HCL_ProcessReadings(phc->clock, n_readings, readings, &phc_ts, &sys_ts, &phc_err))
    return 0;
-  }

-  offset = UTI_DiffTimespecsToDouble(&phc_ts, &sys_ts);
+  LCL_CookTime(&sys_ts, &local_ts, &local_err);
+  HCL_AccumulateSample(phc->clock, &phc_ts, &local_ts, phc_err + local_err);

-  DEBUG_LOG("PHC offset: %+.9f err: %.9f", offset, phc_err);
+  if (phc->extpps)
+    return 0;

-  return RCL_AddSample(instance, &sys_ts, offset, LEAP_Normal);
+  DEBUG_LOG("PHC offset: %+.9f err: %.9f",
+            UTI_DiffTimespecsToDouble(&phc_ts, &sys_ts), phc_err);
+
+  return RCL_AddSample(instance, &sys_ts, &phc_ts, LEAP_Normal);
 }

 RefclockDriver RCL_PHC_driver = {
--- a/refclock_pps.c
+++ b/refclock_pps.c
@@ -61,49 +61,36 @@ static int pps_initialise(RCL_Instance instance) {
  edge_clear = RCL_GetDriverOption(instance, "clear") ? 1 : 0;

  fd = open(path, O_RDWR);
-  if (fd < 0) {
+  if (fd < 0)
    LOG_FATAL("Could not open %s : %s", path, strerror(errno));
-    return 0;
-  }

  UTI_FdSetCloexec(fd);

-  if (time_pps_create(fd, &handle) < 0) {
+  if (time_pps_create(fd, &handle) < 0)
    LOG_FATAL("time_pps_create() failed on %s : %s", path, strerror(errno));
-    return 0;
-  }

-  if (time_pps_getcap(handle, &mode) < 0) {
+  if (time_pps_getcap(handle, &mode) < 0)
    LOG_FATAL("time_pps_getcap() failed on %s : %s", path, strerror(errno));
-    return 0;
-  }

-  if (time_pps_getparams(handle, &params) < 0) {
+  if (time_pps_getparams(handle, &params) < 0)
    LOG_FATAL("time_pps_getparams() failed on %s : %s", path, strerror(errno));
-    return 0;
-  }

  if (!edge_clear) {
-    if (!(mode & PPS_CAPTUREASSERT)) {
+    if (!(mode & PPS_CAPTUREASSERT))
      LOG_FATAL("CAPTUREASSERT not supported on %s", path);
-      return 0;
-    }
+
    params.mode |= PPS_CAPTUREASSERT;
    params.mode &= ~PPS_CAPTURECLEAR;
  } else {
-    if (!(mode & PPS_CAPTURECLEAR)) {
+    if (!(mode & PPS_CAPTURECLEAR))
      LOG_FATAL("CAPTURECLEAR not supported on %s", path);
-      return 0;
-    }
+
    params.mode |= PPS_CAPTURECLEAR;
    params.mode &= ~PPS_CAPTUREASSERT;
  }

-  if (time_pps_setparams(handle, &params) < 0) {
+  if (time_pps_setparams(handle, &params) < 0)
    LOG_FATAL("time_pps_setparams() failed on %s : %s", path, strerror(errno));
-    return 0;
-  }
-

  pps = MallocNew(struct pps_instance);
  pps->handle = handle;
--- a/refclock_shm.c
+++ b/refclock_shm.c
@@ -95,7 +95,6 @@ static int shm_poll(RCL_Instance instance)
 {
  struct timespec receive_ts, clock_ts;
  struct shmTime t, *shm;
-  double offset;

  shm = (struct shmTime *)RCL_GetDriverData(instance);

@@ -124,9 +123,8 @@ static int shm_poll(RCL_Instance instance)

  UTI_NormaliseTimespec(&clock_ts);
  UTI_NormaliseTimespec(&receive_ts);
-  offset = UTI_DiffTimespecsToDouble(&clock_ts, &receive_ts);

-  return RCL_AddSample(instance, &receive_ts, offset, t.leap);
+  return RCL_AddSample(instance, &receive_ts, &clock_ts, t.leap);
 }

 RefclockDriver RCL_SHM_driver = {
--- a/refclock_sock.c
+++ b/refclock_sock.c
@@ -58,23 +58,63 @@ struct sock_sample {
  int magic;
 };

+/* On 32-bit glibc-based systems enable conversion between timevals using
+   32-bit and 64-bit time_t to support SOCK clients compiled with different
+   time_t size than chrony */
+#ifdef __GLIBC_PREREQ
+#if __GLIBC_PREREQ(2, 34) && __TIMESIZE == 32
+#define CONVERT_TIMEVAL 1
+#if defined(_TIME_BITS) && _TIME_BITS == 64
+typedef int32_t alt_time_t;
+typedef int32_t alt_suseconds_t;
+#else
+typedef int64_t alt_time_t;
+typedef int64_t alt_suseconds_t;
+#endif
+struct alt_timeval {
+  alt_time_t tv_sec;
+  alt_suseconds_t tv_usec;
+};
+#endif
+#endif
+
 static void read_sample(int sockfd, int event, void *anything)
 {
+  char buf[sizeof (struct sock_sample) + 16];
+  struct timespec sys_ts, ref_ts;
  struct sock_sample sample;
-  struct timespec ts;
  RCL_Instance instance;
  int s;

  instance = (RCL_Instance)anything;

-  s = recv(sockfd, &sample, sizeof (sample), 0);
+  s = recv(sockfd, buf, sizeof (buf), 0);

  if (s < 0) {
    DEBUG_LOG("Could not read SOCK sample : %s", strerror(errno));
    return;
  }

-  if (s != sizeof (sample)) {
+  if (s == sizeof (sample)) {
+    memcpy(&sample, buf, sizeof (sample));
+#ifdef CONVERT_TIMEVAL
+  } else if (s == sizeof (sample) - sizeof (struct timeval) + sizeof (struct alt_timeval)) {
+    struct alt_timeval atv;
+    memcpy(&atv, buf, sizeof (atv));
+#ifndef HAVE_LONG_TIME_T
+    if (atv.tv_sec > INT32_MAX || atv.tv_sec < INT32_MIN ||
+        atv.tv_usec > INT32_MAX || atv.tv_usec < INT32_MIN) {
+      DEBUG_LOG("Could not convert 64-bit timeval");
+      return;
+    }
+#endif
+    sample.tv.tv_sec = atv.tv_sec;
+    sample.tv.tv_usec = atv.tv_usec;
+    DEBUG_LOG("Converted %d-bit timeval", 8 * (int)sizeof (alt_time_t));
+    memcpy((char *)&sample + sizeof (struct timeval), buf + sizeof (struct alt_timeval),
+           sizeof (sample) - sizeof (struct timeval));
+#endif
+  } else {
    DEBUG_LOG("Unexpected length of SOCK sample : %d != %ld",
              s, (long)sizeof (sample));
    return;
@@ -86,13 +126,18 @@ static void read_sample(int sockfd, int event, void *anything)
    return;
  }

-  UTI_TimevalToTimespec(&sample.tv, &ts);
-  UTI_NormaliseTimespec(&ts);
+  UTI_TimevalToTimespec(&sample.tv, &sys_ts);
+  UTI_NormaliseTimespec(&sys_ts);
+
+  if (!UTI_IsTimeOffsetSane(&sys_ts, sample.offset))
+    return;
+
+  UTI_AddDoubleToTimespec(&sys_ts, sample.offset, &ref_ts);

  if (sample.pulse) {
-    RCL_AddPulse(instance, &ts, sample.offset);
+    RCL_AddPulse(instance, &sys_ts, sample.offset);
  } else {
-    RCL_AddSample(instance, &ts, sample.offset, sample.leap);
+    RCL_AddSample(instance, &sys_ts, &ref_ts, sample.leap);
  }
 }

--- a/reference.c
+++ b/reference.c
@@ -3,7 +3,7 @@

 **********************************************************************
 * Copyright (C) Richard P. Curnow  1997-2003
- * Copyright (C) Miroslav Lichvar  2009-2018
+ * Copyright (C) Miroslav Lichvar  2009-2018, 2020, 2022
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
@@ -112,6 +112,9 @@ static void update_drift_file(double, double);
 /* Leap second handling mode */
 static REF_LeapMode leap_mode;

+/* Time of UTC midnight of the upcoming or previous leap second */
+static time_t leap_when;
+
 /* Flag indicating the clock was recently corrected for leap second and it may
   not have correct time yet (missing 23:59:60 in the UTC time scale) */
 static int leap_in_progress;
@@ -147,6 +150,9 @@ static SCH_TimeoutID fb_drift_timeout_id;
 static double last_ref_update;
 static double last_ref_update_interval;

+static double last_ref_adjustment;
+static int ref_adjustments;
+
 /* ================================================== */

 static NTP_Leap get_tz_leap(time_t when, int *tai_offset);
@@ -246,6 +252,7 @@ REF_Initialise(void)
  enable_local_stratum = CNF_AllowLocalReference(&local_stratum, &local_orphan, &local_distance);
  UTI_ZeroTimespec(&local_ref_time);

+  leap_when = 0;
  leap_timeout_id = 0;
  leap_in_progress = 0;
  leap_mode = CNF_GetLeapSecMode();
@@ -282,6 +289,8 @@ REF_Initialise(void)
  UTI_ZeroTimespec(&our_ref_time);
  last_ref_update = 0.0;
  last_ref_update_interval = 0.0;
+  last_ref_adjustment = 0.0;
+  ref_adjustments = 0;

  LCL_AddParameterChangeHandler(handle_slew, NULL);

@@ -300,6 +309,8 @@ REF_Finalise(void)
    update_drift_file(LCL_ReadAbsoluteFrequency(), our_skew);
  }

+  LCL_RemoveParameterChangeHandler(handle_slew, NULL);
+
  Free(fb_drifts);

  initialised = 0;
@@ -485,8 +496,7 @@ maybe_log_offset(double offset, time_t now)
  abs_offset = fabs(offset);

  if (abs_offset > log_change_threshold) {
-    LOG(LOGS_WARN, "System clock wrong by %.6f seconds, adjustment started",
-        -offset);
+    LOG(LOGS_WARN, "System clock wrong by %.6f seconds", -offset);
  }

  if (do_mail_change &&
@@ -552,8 +562,7 @@ is_offset_ok(double offset)
    return 1;
  }

-  offset = fabs(offset);
-  if (offset > max_offset) {
+  if (fabs(offset) > max_offset) {
    LOG(LOGS_WARN, 
        "Adjustment of %.3f seconds exceeds the allowed maximum of %.3f seconds (%s) ",
        -offset, max_offset, !max_offset_ignore ? "exiting" : "ignored");
@@ -720,10 +729,12 @@ set_leap_timeout(time_t now)
  if (!our_leap_sec)
    return;

+  leap_when = (now / (24 * 3600) + 1) * (24 * 3600);
+
  /* Insert leap second at 0:00:00 UTC, delete at 23:59:59 UTC.  If the clock
     will be corrected by the system, timeout slightly sooner to be sure it
     will happen before the system correction. */
-  when.tv_sec = (now / (24 * 3600) + 1) * (24 * 3600);
+  when.tv_sec = leap_when;
  when.tv_nsec = 0;
  if (our_leap_sec < 0)
    when.tv_sec--;
@@ -767,7 +778,7 @@ update_leap_status(NTP_Leap leap, time_t now, int reset)
  }
  
  if ((leap_sec != our_leap_sec || tai_offset != our_tai_offset)
-      && !REF_IsLeapSecondClose()) {
+      && !REF_IsLeapSecondClose(NULL, 0.0)) {
    our_leap_sec = leap_sec;
    our_tai_offset = tai_offset;

@@ -954,6 +965,27 @@ fuzz_ref_time(struct timespec *ts)

 /* ================================================== */

+static double
+get_correction_rate(double offset_sd, double update_interval)
+{
+  /* We want to correct the offset quickly, but we also want to keep the
+     frequency error caused by the correction itself low.
+
+     Define correction rate as the area of the region bounded by the graph of
+     offset corrected in time.  Set the rate so that the time needed to correct
+     an offset equal to the current sourcestats stddev will be equal to the
+     update interval multiplied by the correction time ratio (assuming linear
+     adjustment).  The offset and the time needed to make the correction are
+     inversely proportional.
+
+     This is only a suggestion and it's up to the system driver how the
+     adjustment will be executed. */
+
+  return correction_time_ratio * 0.5 * offset_sd * update_interval;
+}
+
+/* ================================================== */
+
 void
 REF_SetReference(int stratum, NTP_Leap leap, int combined_sources,
                 uint32_t ref_id, IPAddr *ref_ip, struct timespec *ref_time,
@@ -963,7 +995,7 @@ REF_SetReference(int stratum, NTP_Leap leap, int combined_sources,
 {
  double uncorrected_offset, accumulate_offset, step_offset;
  double residual_frequency, local_abs_frequency;
-  double elapsed, mono_now, update_interval, correction_rate, orig_root_distance;
+  double elapsed, mono_now, update_interval, orig_root_distance;
  struct timespec now, raw_now;
  int manual;

@@ -1012,27 +1044,12 @@ REF_SetReference(int stratum, NTP_Leap leap, int combined_sources,
  our_residual_freq = residual_frequency;
  our_root_delay = root_delay;
  our_root_dispersion = root_dispersion;
-  our_frequency_sd = offset_sd;
+  our_frequency_sd = frequency_sd;
  our_offset_sd = offset_sd;
  last_ref_update = mono_now;
  last_ref_update_interval = update_interval;
  last_offset = offset;

-  /* We want to correct the offset quickly, but we also want to keep the
-     frequency error caused by the correction itself low.
-
-     Define correction rate as the area of the region bounded by the graph of
-     offset corrected in time. Set the rate so that the time needed to correct
-     an offset equal to the current sourcestats stddev will be equal to the
-     update interval multiplied by the correction time ratio (assuming linear
-     adjustment). The offset and the time needed to make the correction are
-     inversely proportional.
-
-     This is only a suggestion and it's up to the system driver how the
-     adjustment will be executed. */
-
-  correction_rate = correction_time_ratio * 0.5 * offset_sd * update_interval;
-
  /* Check if the clock should be stepped */
  if (is_step_limit_reached(offset, uncorrected_offset)) {
    /* Cancel the uncorrected offset and correct the total offset by step */
@@ -1044,7 +1061,8 @@ REF_SetReference(int stratum, NTP_Leap leap, int combined_sources,
  }

  /* Adjust the clock */
-  LCL_AccumulateFrequencyAndOffset(frequency, accumulate_offset, correction_rate);
+  LCL_AccumulateFrequencyAndOffset(frequency, accumulate_offset,
+                                   get_correction_rate(offset_sd, update_interval));
    
  maybe_log_offset(offset, raw_now.tv_sec);

@@ -1089,6 +1107,27 @@ REF_SetReference(int stratum, NTP_Leap leap, int combined_sources,
      avg2_moving = 1;
    avg2_offset = SQUARE(offset);
  }
+
+  ref_adjustments = 0;
+}
+
+/* ================================================== */
+
+int
+REF_AdjustReference(double offset, double frequency)
+{
+  double adj_corr_rate, ref_corr_rate, mono_now;
+
+  mono_now = SCH_GetLastEventMonoTime();
+  ref_adjustments++;
+
+  adj_corr_rate = get_correction_rate(fabs(offset), mono_now - last_ref_adjustment);
+  ref_corr_rate = get_correction_rate(our_offset_sd, last_ref_update_interval) /
+                  ref_adjustments;
+  last_ref_adjustment = mono_now;
+
+  return LCL_AccumulateFrequencyAndOffsetNoHandlers(frequency, offset,
+                                                    MAX(adj_corr_rate, ref_corr_rate));
 }

 /* ================================================== */
@@ -1290,6 +1329,7 @@ void
 REF_ModifyMaxupdateskew(double new_max_update_skew)
 {
  max_update_skew = new_max_update_skew * 1.0e-6;
+  LOG(LOGS_INFO, "New maxupdateskew %f ppm", new_max_update_skew);
 }

 /* ================================================== */
@@ -1299,6 +1339,7 @@ REF_ModifyMakestep(int limit, double threshold)
 {
  make_step_limit = limit;
  make_step_threshold = threshold;
+  LOG(LOGS_INFO, "New makestep %f %d", threshold, limit);
 }

 /* ================================================== */
@@ -1310,6 +1351,7 @@ REF_EnableLocal(int stratum, double distance, int orphan)
  local_stratum = CLAMP(1, stratum, NTP_MAX_STRATUM - 1);
  local_distance = distance;
  local_orphan = !!orphan;
+  LOG(LOGS_INFO, "%s local reference mode", "Enabled");
 }

 /* ================================================== */
@@ -1318,28 +1360,32 @@ void
 REF_DisableLocal(void)
 {
  enable_local_stratum = 0;
+  LOG(LOGS_INFO, "%s local reference mode", "Disabled");
 }

 /* ================================================== */

 #define LEAP_SECOND_CLOSE 5

-int REF_IsLeapSecondClose(void)
+static int
+is_leap_close(time_t t)
+{
+  return leap_when != 0 &&
+         t >= leap_when - LEAP_SECOND_CLOSE && t < leap_when + LEAP_SECOND_CLOSE;
+}
+
+/* ================================================== */
+
+int REF_IsLeapSecondClose(struct timespec *ts, double offset)
 {
  struct timespec now, now_raw;
-  time_t t;
-
-  if (!our_leap_sec)
-    return 0;

  SCH_GetLastEventTime(&now, NULL, &now_raw);

-  t = now.tv_sec > 0 ? now.tv_sec : -now.tv_sec;
-  if ((t + LEAP_SECOND_CLOSE) % (24 * 3600) < 2 * LEAP_SECOND_CLOSE)
+  if (is_leap_close(now.tv_sec) || is_leap_close(now_raw.tv_sec))
    return 1;

-  t = now_raw.tv_sec > 0 ? now_raw.tv_sec : -now_raw.tv_sec;
-  if ((t + LEAP_SECOND_CLOSE) % (24 * 3600) < 2 * LEAP_SECOND_CLOSE)
+  if (ts && (is_leap_close(ts->tv_sec) || is_leap_close(ts->tv_sec + offset)))
    return 1;

  return 0;
--- a/reference.h
+++ b/reference.h
@@ -162,6 +162,10 @@ extern void REF_SetManualReference
 extern void
 REF_SetUnsynchronised(void);

+/* Make a small correction of the clock without updating the reference
+   parameters and calling the clock change handlers */
+extern int REF_AdjustReference(double offset, double frequency);
+
 /* Announce a leap second before the full reference update */
 extern void REF_UpdateLeapStatus(NTP_Leap leap);

@@ -184,9 +188,9 @@ extern void REF_ModifyMakestep(int limit, double threshold);
 extern void REF_EnableLocal(int stratum, double distance, int orphan);
 extern void REF_DisableLocal(void);

-/* Check if current raw or cooked time is close to a leap second
-   and is better to discard any measurements */
-extern int REF_IsLeapSecondClose(void);
+/* Check if either of the current raw and cooked time, and optionally a
+   provided timestamp with an offset, is close to a leap second */
+extern int REF_IsLeapSecondClose(struct timespec *ts, double offset);

 /* Return TAI-UTC offset corresponding to a time in UTC if available */
 extern int REF_GetTaiOffset(struct timespec *ts);
--- a/reports.h
+++ b/reports.h
@@ -36,8 +36,14 @@ typedef struct {
  int stratum;
  int poll;
  enum {RPT_NTP_CLIENT, RPT_NTP_PEER, RPT_LOCAL_REFERENCE} mode;
-  enum {RPT_SYNC, RPT_UNREACH, RPT_FALSETICKER, RPT_JITTERY, RPT_CANDIDATE, RPT_OUTLIER} state;
-  int sel_options;
+  enum {
+    RPT_NONSELECTABLE,
+    RPT_FALSETICKER,
+    RPT_JITTERY,
+    RPT_SELECTABLE,
+    RPT_UNSELECTED,
+    RPT_SELECTED,
+  } state;

  int reachability;
  unsigned long latest_meas_ago; /* seconds */
@@ -78,8 +84,8 @@ typedef struct {

 typedef struct {
  struct timespec ref_time;
-  unsigned short n_samples;
-  unsigned short n_runs;
+  unsigned long n_samples;
+  unsigned long n_runs;
  unsigned long span_seconds;
  double rtc_seconds_fast;
  double rtc_gain_rate_ppm;
@@ -88,22 +94,38 @@ typedef struct {
 typedef struct {
  IPAddr ip_addr;
  uint32_t ntp_hits;
+  uint32_t nke_hits;
  uint32_t cmd_hits;
  uint16_t ntp_drops;
+  uint16_t nke_drops;
  uint16_t cmd_drops;
  int8_t ntp_interval;
+  int8_t nke_interval;
  int8_t cmd_interval;
  int8_t ntp_timeout_interval;
  uint32_t last_ntp_hit_ago;
+  uint32_t last_nke_hit_ago;
  uint32_t last_cmd_hit_ago;
 } RPT_ClientAccessByIndex_Report;

 typedef struct {
-  uint32_t ntp_hits;
-  uint32_t cmd_hits;
-  uint32_t ntp_drops;
-  uint32_t cmd_drops;
-  uint32_t log_drops;
+  uint64_t ntp_hits;
+  uint64_t nke_hits;
+  uint64_t cmd_hits;
+  uint64_t ntp_drops;
+  uint64_t nke_drops;
+  uint64_t cmd_drops;
+  uint64_t log_drops;
+  uint64_t ntp_auth_hits;
+  uint64_t ntp_interleaved_hits;
+  uint64_t ntp_timestamps;
+  uint64_t ntp_span_seconds;
+  uint64_t ntp_daemon_rx_timestamps;
+  uint64_t ntp_daemon_tx_timestamps;
+  uint64_t ntp_kernel_rx_timestamps;
+  uint64_t ntp_kernel_tx_timestamps;
+  uint64_t ntp_hw_rx_timestamps;
+  uint64_t ntp_hw_tx_timestamps;
 } RPT_ServerStatsReport;

 typedef struct {
@@ -158,6 +180,33 @@ typedef struct {
  uint32_t total_tx_count;
  uint32_t total_rx_count;
  uint32_t total_valid_count;
+  uint32_t total_good_count;
 } RPT_NTPReport;

+typedef struct {
+  NTP_AuthMode mode;
+  uint32_t key_id;
+  int key_type;
+  int key_length;
+  int ke_attempts;
+  uint32_t last_ke_ago;
+  int cookies;
+  int cookie_length;
+  int nak;
+} RPT_AuthReport;
+
+typedef struct {
+  uint32_t ref_id;
+  IPAddr ip_addr;
+  char state_char;
+  int authentication;
+  NTP_Leap leap;
+  int conf_options;
+  int eff_options;
+  uint32_t last_sample_ago;
+  double score;
+  double lo_limit;
+  double hi_limit;
+} RPT_SelectReport;
+
 #endif /* GOT_REPORTS_H */
--- a/rtc.c
+++ b/rtc.c
@@ -148,6 +148,8 @@ RTC_Initialise(int initial_set)
    if (driver.init) {
      if ((driver.init)()) {
        driver_initialised = 1;
+      } else {
+        LOG(LOGS_ERR, "RTC driver could not be initialised");
      }
    } else {
      LOG(LOGS_ERR, "RTC not supported on this operating system");
--- a/rtc_linux.c
+++ b/rtc_linux.c
@@ -64,7 +64,7 @@ static OperatingMode operating_mode = OM_NORMAL;

 /* ================================================== */

-static int fd = -1;
+static int fd;

 #define LOWEST_MEASUREMENT_PERIOD 15
 #define HIGHEST_MEASUREMENT_PERIOD 480
@@ -82,16 +82,12 @@ static int skip_interrupts;
 #define MAX_SAMPLES 64

 /* Real time clock samples.  We store the seconds count as originally
-   measured, together with a 'trim' that compensates these values for
-   any steps made to the RTC to bring it back into line
-   occasionally.  The trim is in seconds. */
+   measured. */
 static time_t *rtc_sec = NULL;
-static double *rtc_trim = NULL;

 /* Reference time, against which delta times on the RTC scale are measured */
 static time_t rtc_ref;

-
 /* System clock samples associated with the above samples. */
 static struct timespec *system_times = NULL;

@@ -145,7 +141,7 @@ static double file_ref_offset, file_rate_ppm;
 /* ================================================== */

 /* Flag to remember whether to assume the RTC is running on UTC */
-static int rtc_on_utc = 1;
+static int rtc_on_utc;

 /* ================================================== */

@@ -168,7 +164,6 @@ discard_samples(int new_first)
  n_to_save = n_samples - new_first;

  memmove(rtc_sec, rtc_sec + new_first, n_to_save * sizeof(time_t));
-  memmove(rtc_trim, rtc_trim + new_first, n_to_save * sizeof(double));
  memmove(system_times, system_times + new_first, n_to_save * sizeof(struct timespec));

  n_samples = n_to_save;
@@ -188,21 +183,16 @@ accumulate_sample(time_t rtc, struct timespec *sys)
  }

  /* Discard all samples if the RTC was stepped back (not our trim) */
-  if (n_samples > 0 && rtc_sec[n_samples - 1] - rtc >= rtc_trim[n_samples - 1]) {
+  if (n_samples > 0 && rtc_sec[n_samples - 1] >= rtc) {
    DEBUG_LOG("RTC samples discarded");
    n_samples = 0;
  }

  /* Always use most recent sample as reference */
-  /* use sample only if n_sample is not negative*/
-  if(n_samples >=0)
-  {
  rtc_ref = rtc;
  rtc_sec[n_samples] = rtc;
-  rtc_trim[n_samples] = 0.0;
  system_times[n_samples] = *sys;
  ++n_samples_since_regression;
-  }
  ++n_samples;
 }

@@ -227,7 +217,7 @@ run_regression(int new_sample,
  if (n_samples > 0) {

    for (i=0; i<n_samples; i++) {
-      rtc_rel[i] = rtc_trim[i] + (double)(rtc_sec[i] - rtc_ref);
+      rtc_rel[i] = (double)(rtc_sec[i] - rtc_ref);
      offsets[i] = ((double) (rtc_ref - system_times[i].tv_sec) -
                    (1.0e-9 * system_times[i].tv_nsec) +
                    rtc_rel[i]);
@@ -434,6 +424,7 @@ setup_config(void)
 static void
 read_coefs_from_file(void)
 {
+  double ref_time;
  FILE *in;

  if (!tried_to_load_coefs) {
@@ -444,11 +435,12 @@ read_coefs_from_file(void)

    if (coefs_file_name &&
        (in = UTI_OpenFile(NULL, coefs_file_name, NULL, 'r', 0))) {
-      if (fscanf(in, "%d%ld%lf%lf",
+      if (fscanf(in, "%d%lf%lf%lf",
                 &valid_coefs_from_file,
-                 &file_ref_time,
+                 &ref_time,
                 &file_ref_offset,
                 &file_rate_ppm) == 4) {
+        file_ref_time = ref_time;
      } else {
        LOG(LOGS_WARN, "Could not read coefficients from %s", coefs_file_name);
      }
@@ -472,7 +464,7 @@ write_coefs_to_file(int valid,time_t ref_time,double offset,double rate)
    return RTC_ST_BADFILE;

  /* Gain rate is written out in ppm */
-  fprintf(out, "%1d %ld %.6f %.3f\n", valid, ref_time, offset, 1.0e6 * rate);
+  fprintf(out, "%1d %.0f %.6f %.3f\n", valid, (double)ref_time, offset, 1.0e6 * rate);
  fclose(out);

  /* Rename the temporary file to the correct location */
@@ -525,7 +517,6 @@ RTC_Linux_Initialise(void)
  UTI_FdSetCloexec(fd);

  rtc_sec = MallocArray(time_t, MAX_SAMPLES);
-  rtc_trim = MallocArray(double, MAX_SAMPLES);
  system_times = MallocArray(struct timespec, MAX_SAMPLES);

  /* Setup details depending on configuration options */
@@ -573,8 +564,11 @@ RTC_Linux_Finalise(void)
    (void) RTC_Linux_WriteParameters();

  }
+
+  if (rtc_sec)
+    LCL_RemoveParameterChangeHandler(slew_samples, NULL);
+
  Free(rtc_sec);
-  Free(rtc_trim);
  Free(system_times);
 }

@@ -635,11 +629,7 @@ handle_initial_trim(void)
  run_regression(1, &coefs_valid, &coef_ref_time, &coef_seconds_fast, &coef_gain_rate);

  n_samples_since_regression = 0;
-
-  /* Set sample number to -1 so the next sample is not used, as it will not yet be corrected for System Trim*/
-
-  n_samples = -1;
-
+  n_samples = 0;

  read_coefs_from_file();

@@ -1024,8 +1014,7 @@ RTC_Linux_GetReport(RPT_RTC_Report *report)
  report->n_samples = n_samples;
  report->n_runs = n_runs;
  if (n_samples > 1) {
-    report->span_seconds = ((rtc_sec[n_samples-1] - rtc_sec[0]) +
-                            (long)(rtc_trim[n_samples-1] - rtc_trim[0]));
+    report->span_seconds = rtc_sec[n_samples - 1] - rtc_sec[0];
  } else {
    report->span_seconds = 0;
  }
--- a/samplefilt.c
+++ b/samplefilt.c
@@ -162,6 +162,14 @@ SPF_GetNumberOfSamples(SPF_Instance filter)

 /* ================================================== */

+int
+SPF_GetMaxSamples(SPF_Instance filter)
+{
+  return filter->max_samples;
+}
+
+/* ================================================== */
+
 double
 SPF_GetAvgSampleDispersion(SPF_Instance filter)
 {
@@ -170,11 +178,21 @@ SPF_GetAvgSampleDispersion(SPF_Instance filter)

 /* ================================================== */

-void
-SPF_DropSamples(SPF_Instance filter)
+static void
+drop_samples(SPF_Instance filter, int keep_last)
 {
  filter->index = -1;
  filter->used = 0;
+  if (!keep_last)
+    filter->last = -1;
+}
+
+/* ================================================== */
+
+void
+SPF_DropSamples(SPF_Instance filter)
+{
+  drop_samples(filter, 0);
 }

 /* ================================================== */
@@ -267,7 +285,7 @@ select_samples(SPF_Instance filter)
    }
  }

-  for (i = j = 0, k = -1; i < filter->used; i++) {
+  for (i = j = 0; i < filter->used; i++) {
    if (selected[i] != -1)
      selected[j++] = (selected[i] + filter->used - o) % filter->used;
  }
@@ -386,7 +404,6 @@ combine_selected_samples(SPF_Instance filter, int n, NTP_Sample *result)
  result->root_dispersion = MAX(disp, mean_root_dispersion);
  result->peer_delay = mean_peer_delay;
  result->root_delay = mean_root_delay;
-  result->stratum = last_sample->stratum;

  return 1;
 }
@@ -400,17 +417,40 @@ SPF_GetFilteredSample(SPF_Instance filter, NTP_Sample *sample)

  n = select_samples(filter);

+  DEBUG_LOG("selected %d from %d samples", n, filter->used);
+
  if (n < 1)
    return 0;

  if (!combine_selected_samples(filter, n, sample))
    return 0;

-  SPF_DropSamples(filter);
+  drop_samples(filter, 1);

  return 1;
 }

+/* ================================================== */
+
+static int
+get_first_last(SPF_Instance filter, int *first, int *last)
+{
+  if (filter->last < 0)
+    return 0;
+
+  /* Always slew the last sample as it may be returned even if no new
+     samples were accumulated */
+  if (filter->used > 0) {
+    *first = 0;
+    *last = filter->used - 1;
+  } else {
+    *first = *last = filter->last;
+  }
+
+  return 1;
+}
+
+
 /* ================================================== */

 void
@@ -419,18 +459,9 @@ SPF_SlewSamples(SPF_Instance filter, struct timespec *when, double dfreq, double
  int i, first, last;
  double delta_time;

-  if (filter->last < 0)
+  if (!get_first_last(filter, &first, &last))
    return;

-  /* Always slew the last sample as it may be returned even if no new
-     samples were accumulated */
-  if (filter->used > 0) {
-    first = 0;
-    last = filter->used - 1;
-  } else {
-    first = last = filter->last;
-  }
-
  for (i = first; i <= last; i++) {
    UTI_AdjustTimespec(&filter->samples[i].time, when, &filter->samples[i].time,
                       &delta_time, dfreq, doffset);
@@ -440,6 +471,20 @@ SPF_SlewSamples(SPF_Instance filter, struct timespec *when, double dfreq, double

 /* ================================================== */

+void
+SPF_CorrectOffset(SPF_Instance filter, double doffset)
+{
+  int i, first, last;
+
+  if (!get_first_last(filter, &first, &last))
+    return;
+
+  for (i = first; i <= last; i++)
+    filter->samples[i].offset -= doffset;
+}
+
+/* ================================================== */
+
 void
 SPF_AddDispersion(SPF_Instance filter, double dispersion)
 {
--- a/Show More
+++ b/Show More