CLOCKDIFF(8) - Linux man page online | Administration and privileged commands
Measure clock difference between hosts.
28 June 2019
CLOCKDIFF(8) System Manager's Manual: iputils CLOCKDIFF(8)
iputils-161105 28 June 2019 CLOCKDIFF(8)
NAMEclockdiff - measure clock difference between hosts
SYNOPSISclockdiff [-o] [-o1] destination
DESCRIPTIONclockdiff 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 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 prespec‐ ified 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 time‐ stamps 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 ALSOping(8), arping(8), tracepath(8).
REFERENCES ICMP ECHO, RFC0792, page 14.  ICMP TIMESTAMP, RFC0792, page 16.  IP TIMESTAMP option, RFC0791, 3.1, page 16.
AUTHORclockdiff was compiled by Alexey Kuznetsov <@ms2.inr.ac.ru>. It was based on code borrowed from BSD timed daemon. It is now maintained by YOSHIFUJI Hideaki <yosh‐ @skbuff.net>.
SECURITYclockdiff requires CAP_NET_RAW capability to be executed. It is safe to be used as set-uid root.
AVAILABILITYclockdiff is part of iputils package and the latest versions are available in source form at http://www.skbuff.net/iputils/iputils-current.tar.bz2.
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|refer to||arping(8) | ping(8) | tracepath(8)|