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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | WARNINGS | SEE ALSO | REFERENCES | AUTHOR | SECURITY | AVAILABILITY | COLOPHON |
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CLOCKDIFF(8) 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 [2] packets or, optionally, IP
TIMESTAMP option [3] option added to ICMP ECHO. [1]
-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.
· 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 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.
· clockdiff shows difference in time modulo 24 days.
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 capability to be executed. It is safe
to be used as set-uid root.
clockdiff is part of iputils package.
This page is part of the iputils (IP utilities) project. Information
about the project can be found at ⟨http://www.skbuff.net/iputils/⟩.
If you have a bug report for this manual page, send it to
yoshfuji@skbuff.net, netdev@vger.kernel.org. This page was obtained
from the project's upstream Git repository
⟨https://github.com/iputils/iputils.git⟩ on 2018-02-02. (At that
time, the date of the most recent commit that was found in the repos‐
itory was 2017-11-14.) If you discover any rendering problems in
this HTML version of the page, or you believe there is a better or
more up-to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not part
of the original manual page), send a mail to man-pages@man7.org
iputils s20161105 CLOCKDIFF(8)
Pages that refer to this page: arping(8)
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