clockdiff man page

clockdiff — measure clock difference between hosts


clockdiff [-o] [-o1] destination


clockdiff Measures clock difference between us and destination with 1 msec resolution using ICMP TIMESTAMP [2] packets or, optionally, IP TIMESTAMP option [3] option added to ICMP ECHO. [1]



Use IP TIMESTAMP with ICMP ECHO instead of ICMP TIMESTAMP messages. It is useful with some destinations, which do not support ICMP TIMESTAMP (f.e. Solaris <2.4).


Slightly different form of -o, namely it uses three-term IP TIMESTAMP with prespecified hop addresses instead of four term one. What flavor works better depends on target host. Particularly, -o is better for Linux.


See Also

ping(8), arping(8), tracepath(8).


[1] ICMP ECHO, RFC0792, page 14.

[2] ICMP TIMESTAMP, RFC0792, page 16.

[3] IP TIMESTAMP option, RFC0791, 3.1, page 16.


clockdiff was compiled by Alexey Kuznetsov <>. It was based on code borrowed from BSD timed daemon. It is now maintained by YOSHIFUJI Hideaki <>.


clockdiff requires CAP_NET_RAW capability to be executed. It is safe to be used as set-uid root.


clockdiff is part of iputils package and the latest versions are  available in source form at

Referenced By


iputils-161105 System Manager's Manual: iputils