Provided by: iputils-clockdiff_20121221-5ubuntu2_i386 bug

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 [2]  packets  or,  optionally,  IP
       TIMESTAMP option [3] option added to ICMP ECHO.  [1]

OPTIONS

       -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

       · 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

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

REFERENCES

       [1] ICMP ECHO, RFC0792, page 14.

       [2] ICMP TIMESTAMP, RFC0792, page 16.

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

AUTHOR

       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

       clockdiff requires CAP_NET_RAW 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-
       current.tar.bz2.