NAME | SYNOPSIS | DESCRIPTION | OPTIONS | WARNINGS | SEE ALSO | REFERENCES | AUTHOR | SECURITY | AVAILABILITY | COLOPHON

CLOCKDIFF(8)          System Manager's Manual: iputils          CLOCKDIFF(8)

NAME         top

       clockdiff - measure clock difference between hosts

SYNOPSIS         top

       clockdiff [-o] [-o1] destination

DESCRIPTION         top

       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]

OPTIONS         top

       -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.

WARNINGS         top

       · 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.

SEE ALSO         top

       ping(8), arping(8), tracepath(8).

REFERENCES         top

       [1] ICMP ECHO, RFC0792, page 14.

       [2] ICMP TIMESTAMP, RFC0792, page 16.

       [3] IP TIMESTAMP option, RFC0791, 3.1, page 16.

AUTHOR         top

       clockdiff was compiled by Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>. It
       was based on code borrowed from BSD timed daemon.  It is now
       maintained by YOSHIFUJI Hideaki <yoshfuji@skbuff.net>.

SECURITY         top

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

AVAILABILITY         top

       clockdiff is part of iputils package and the latest versions are
       available in source form at
       http://www.skbuff.net/iputils/iputils-current.tar.bz2.

COLOPHON         top

       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 
       ⟨git://git.linux-ipv6.org/gitroot/iputils.git⟩ on 2017-07-05.  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-151218                  05 July 2017                    CLOCKDIFF(8)

Pages that refer to this page: arping(8)