1CLOCKDIFF(8) iputils CLOCKDIFF(8)
2
6 clockdiff - measure clock difference between hosts
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9 clockdiff [-o] [-o1] [-V] {destination}
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12 clockdiff Measures clock difference between us and destination with 1
13 msec resolution using ICMP TIMESTAMP [2] packets or, optionally, IP
14 TIMESTAMP option [3] option added to ICMP ECHO. [1]
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17 -o
18 Use IP TIMESTAMP with ICMP ECHO instead of ICMP TIMESTAMP messages.
19 It is useful with some destinations, which do not support ICMP
20 TIMESTAMP (f.e. Solaris <2.4).
21 -o1
23 Slightly different form of -o, namely it uses three-term IP
24 TIMESTAMP with prespecified hop addresses instead of four term one.
25 What flavor works better depends on target host. Particularly, -o
26 is better for Linux.
27 -V
29 Print version and exit.
30
32 · Some nodes (Cisco) use non-standard timestamps, which is allowed
33 by RFC, but makes timestamps mostly useless.
34 · Some nodes generate messed timestamps (Solaris>2.4), when run
36 xntpd. Seems, its IP stack uses a corrupted clock source, which is
37 synchronized to time-of-day clock periodically and jumps randomly
38 making timestamps mostly useless. Good news is that you can use NTP
39 in this case, which is even better.
40 · clockdiff shows difference in time modulo 24 days.
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44 ping(8), arping(8), tracepath(8).
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47 [1] ICMP ECHO, RFC0792, page 14.
48 [2] ICMP TIMESTAMP, RFC0792, page 16.
50 [3] IP TIMESTAMP option, RFC0791, 3.1, page 16.
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54 clockdiff was compiled by Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>. It
55 was based on code borrowed from BSD timed daemon.
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58 clockdiff requires CAP_NET_RAW capability to be executed. It is safe to
59 be used as set-uid root.
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62 clockdiff is part of iputils package.
63iputils s20190515 CLOCKDIFF(8)