diff --git a/candm.h b/candm.h
index 401c015..277fa9a 100644
--- a/candm.h
+++ b/candm.h
@@ -37,7 +37,6 @@
 #define DEFAULT_CANDM_PORT 323
 
 /* Request codes */
-#define REQ_NULL 0
 #define REQ_ONLINE 1
 #define REQ_OFFLINE 2
 #define REQ_BURST 3
@@ -223,11 +222,6 @@ typedef struct {
   int32_t EOR;
 } REQ_Modify_Makestep;
 
-typedef struct {
-  Timespec ts;
-  int32_t EOR;
-} REQ_Logon;
-
 typedef struct {
   Timespec ts;
   int32_t EOR;
@@ -487,7 +481,6 @@ typedef struct {
     REQ_Modify_Polltarget modify_polltarget;
     REQ_Modify_Maxupdateskew modify_maxupdateskew;
     REQ_Modify_Makestep modify_makestep;
-    REQ_Logon logon;
     REQ_Settime settime;
     REQ_Local local;
     REQ_Manual manual;
diff --git a/cmdmon.c b/cmdmon.c
index 4accdf6..841f3bd 100644
--- a/cmdmon.c
+++ b/cmdmon.c
@@ -1595,10 +1595,6 @@ read_from_cmd_socket(int sock_fd, int event, void *anything)
       LOG_SetContext(LOGC_Command);
 
       switch(rx_command) {
-        case REQ_NULL:
-          /* Do nothing */
-          break;
-
         case REQ_DUMP:
           handle_dump(&rx_message, &tx_message);
           break;
@@ -1643,11 +1639,6 @@ read_from_cmd_socket(int sock_fd, int event, void *anything)
           handle_modify_makestep(&rx_message, &tx_message);
           break;
 
-        case REQ_LOGON:
-          /* Authentication is no longer supported, log-on always fails */
-          tx_message.status = htons(STT_FAILED);
-          break;
-
         case REQ_SETTIME:
           handle_settime(&rx_message, &tx_message);
           break;
diff --git a/pktlength.c b/pktlength.c
index 8d5ffa7..d9348ef 100644
--- a/pktlength.c
+++ b/pktlength.c
@@ -55,7 +55,7 @@ struct request_length {
 };
 
 static const struct request_length request_lengths[] = {
-  REQ_LENGTH_ENTRY(null, null),                 /* NULL */
+  { 0, 0 },                                     /* NULL - not supported */
   REQ_LENGTH_ENTRY(online, null),               /* ONLINE */
   REQ_LENGTH_ENTRY(offline, null),              /* OFFLINE */
   REQ_LENGTH_ENTRY(burst, null),                /* BURST */
@@ -65,7 +65,7 @@ static const struct request_length request_lengths[] = {
   REQ_LENGTH_ENTRY(modify_maxdelay, null),      /* MODIFY_MAXDELAY */
   REQ_LENGTH_ENTRY(modify_maxdelayratio, null), /* MODIFY_MAXDELAYRATIO */
   REQ_LENGTH_ENTRY(modify_maxupdateskew, null), /* MODIFY_MAXUPDATESKEW */
-  REQ_LENGTH_ENTRY(logon, null),                /* LOGON */
+  { 0, 0 },                                     /* LOGON - not supported */
   REQ_LENGTH_ENTRY(settime, manual_timestamp),  /* SETTIME */
   { 0, 0 },                                     /* LOCAL */
   REQ_LENGTH_ENTRY(manual, null),               /* MANUAL */