2.7. Monitoring NTP clients

Procedure

1. Display a list of clients by using the chronyc clients command:

   # chronyc clients

2. Review the command output:

   Hostname                          NTP  Drop  Int  IntL  Last  Cmd  Drop  Int  Last
   ====================================================================================
   client1.example.net 			   10 	  0    6 	 - 	 10s 	0 	  0    6   12s
   client2.example.net 			    8 	  0	   6 	 - 	 25s 	0 	  0    6   28s
   desktop-192-0-2-100.example.net 	3 	   	   6 	 - 	  9s 	0 	  0    6   11s

   The output fields include:

   • Hostname: The hostname or IP address of the client.
   • NTP: The number of NTP packets received from the client.
   • Drop: The number of packets dropped by chronyd, typically due to rate-limiting.
   • Int: The client’s polling interval in seconds (as a log base 2 value, e.g., 6 = $2^6$ = 64s).
   • IntL: The average inter-poll interval (in seconds) for the client when rate limiting is active. This field shows '-' if rate limiting is not currently active for the client.
   • Last: The elapsed time since the last NTP packet was received from this client. Use this value to determine which clients are synchronized or recently synchronized.

   • Cmd: The number of chronyc (monitoring) command packets received from the client.

     참고

     If you have a number of clients and the command is slow to return, it might be due to performing DNS lookups. Use the -n option to disable hostname resolution and display IP addresses instead:

     +

     # chronyc -n clients

     중요

     By default, chronyd monitors up to 4,096 clients. If you have more clients than this, you can increase the memory limit with clientloglimit in /etc/chrony.conf file. For example: clientloglimit 10000000