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 prespecified 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 timestamps 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 <email@example.com>. It
was based on code borrowed from BSD timed daemon. It is now maintained
by YOSHIFUJI Hideaki <firstname.lastname@example.org>.
clockdiff requires CAP_NET_RAWIO 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 http://www.skbuff.net/iputils/iputils-