CLOCKDIFF(8) System Manager's Manual: iputils CLOCKDIFF(8)
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  packets or, optionally, IP TIMESTAMP option  option added to
ICMP ECHO. 
-o 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).
-o1 Slightly different form of -o, namely it uses three-term IP TIMESTAMP with prespec-
ified hop addresses instead of four term one. What flavor works better depends on
target host. Particularly, -o is better for Linux.
o Some nodes (Cisco) use non-standard timestamps, which is allowed by RFC, but makes time-
stamps mostly useless.
o Some nodes generate messed timestamps (Solaris>2.4), when run xntpd. Seems, its IP stack
uses a corrupted clock source, which is synchronized to time-of-day clock periodically
and jumps randomly making timestamps mostly useless. Good news is that you can use NTP
in this case, which is even better.
o clockdiff shows difference in time modulo 24 days.
ping(8), arping(8), tracepath(8).
 ICMP ECHO, RFC0792, page 14.
 ICMP TIMESTAMP, RFC0792, page 16.
 IP TIMESTAMP option, RFC0791, 3.1, page 16.
clockdiff was compiled by Alexey Kuznetsov <firstname.lastname@example.org>. It was based on code
borrowed from BSD timed daemon.
clockdiff requires CAP_NET_RAWIO capability to be executed. It is safe to be used as set-
clockdiff is part of iputils package and the latest versions are available in source form
for anonymous ftp ftp://ftp.inr.ac.ru/ip-routing/iputils-current.tar.gz.
iputils-020927 27 September 2002 CLOCKDIFF(8)