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clockdiff - Man Page

measure clock difference between hosts


clockdiff [-o] [-o1] [--time-format ctime iso] [-V] {destination}


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

-T,  --time-format ctime iso

Print time stamp in output either ISO-8601 format or classical ctime format. The ctime format is default. The ISO time stamp includes timezone, and is easier to parse.


Alias of --time-format iso option and argument.

-h,  --help

Print help and exit.

-V,  --version

Print version and exit.


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 <kuznet@ms2.inr.ac.ru>. It was based on code borrowed from BSD timed daemon.


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


clockdiff is part of iputils package.

Referenced By


iputils 20240117