CLOCKDIFF(8) System Manager s Manual: iputils CLOCKDIFF(8)
NAME clockdiff - measure clock difference between hosts
SYNOPSIS clockdiff [ -o] [ -o1] destination
DESCRIPTION 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. 
OPTIONS -o Use IP TIMESTAMP with ICMP ECHO instead of ICMP TIMESTAMP mes- sages. 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 prespecified hop addresses instead of four term one. What flavor works better depends on target host. Particu- larly, -o is better for Linux.
WARNINGS · Some nodes (Cisco) use non-standard timestamps, which is allowed by RFC, but makes timestamps mostly useless.
· Some nodes generate messed timestamps (Solaris>2.4), when run xntpd. Seems, its IP stack uses a corrupted clock source, which is synchro- nized 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.
· clockdiff shows difference in time modulo 24 days.
SEE ALSO ping(8), arping(8), tracepath(8).
REFERENCES  ICMP ECHO, RFC0792, page 14.
 ICMP TIMESTAMP, RFC0792, page 16.
 IP TIMESTAMP option, RFC0791, 3.1, page 16.
AUTHOR clockdiff was compiled by Alexey Kuznetsov <firstname.lastname@example.org>. It was based on code borrowed from BSD timed daemon. It is now maintained by YOSHIFUJI Hideaki <email@example.com>.
SECURITY clockdiff requires CAP_NET_RAWIO capability to be executed. It is safe to be used as set-uid root.
AVAILABILITY clockdiff is part of iputils package and the latest versions are available in source form at http://www.skbuff.net/iputils/iputils-cur- rent.tar.bz2.
iputils-071127 11 December 2014 CLOCKDIFF(8)