clockdiff(8)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 [2] [clockdiff(8)] packets or, op‐
tionally, IP TIMESTAMP option [3] [clockdiff(8)] option added to ICMP
ECHO. [1] [clockdiff(8)]
OPTIONS-o Use IP TIMESTAMP with ICMP ECHO instead of ICMP TIMESTAMP mes‐
sages. 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. Particu‐
larly, -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 (Solaris2.4), when run xntpd.
Seems, its IP stack uses a corrupted clock source, which is synchro‐
nized 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)[Cross reference to non-existant ID “ping”], arping(8)[Cross
reference to non-existant ID “arping”], tracepath(8)[Cross reference to
non-existant ID “tracepath”].
REFERENCES
[1]
[2]
[3]
AUTHORclockdiff was compiled by Alexey Kuznetsov kuznet@ms2.inr.ac.ru
⟨mailto:kuznet@ms2.inr.ac.ru⟩ . It was based on code borrowed from BSD
timed daemon. It is now maintained by YOSHIFUJI Hideaki yoshfu‐
ji@skbuff.net ⟨mailto:yoshfuji@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 avail‐
able in source form at ⟨http://www.skbuff.net/iputils/iputils-cur‐
rent.tar.bz2⟩.
iputils- 13 August 2013 clockdiff(8)
