1CLOCKDIFF(8) iputils CLOCKDIFF(8)
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6 clockdiff - measure clock difference between hosts
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9 clockdiff [-o] [-o1] destination
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13 clockdiff Measures clock difference between us and destination with 1
14 msec resolution using ICMP TIMESTAMP [2] packets or, optionally, IP
15 TIMESTAMP option [3] option added to ICMP ECHO. [1]
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18 -o
19 Use IP TIMESTAMP with ICMP ECHO instead of ICMP TIMESTAMP messages.
20 It is useful with some destinations, which do not support ICMP
21 TIMESTAMP (f.e. Solaris <2.4).
22 -o1
24 Slightly different form of -o, namely it uses three-term IP
25 TIMESTAMP with prespecified hop addresses instead of four term one.
26 What flavor works better depends on target host. Particularly, -o
27 is better for Linux.
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30 · Some nodes (Cisco) use non-standard timestamps, which is allowed
31 by RFC, but makes timestamps mostly useless.
32 · Some nodes generate messed timestamps (Solaris>2.4), when run
34 xntpd. Seems, its IP stack uses a corrupted clock source, which is
35 synchronized to time-of-day clock periodically and jumps randomly
36 making timestamps mostly useless. Good news is that you can use NTP
37 in this case, which is even better.
38 · clockdiff shows difference in time modulo 24 days.
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42 ping(8), arping(8), tracepath(8).
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45 [1] ICMP ECHO, RFC0792, page 14.
46 [2] ICMP TIMESTAMP, RFC0792, page 16.
48 [3] IP TIMESTAMP option, RFC0791, 3.1, page 16.
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52 clockdiff was compiled by Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>. It
53 was based on code borrowed from BSD timed daemon.
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56 clockdiff requires CAP_NET_RAW capability to be executed. It is safe to
57 be used as set-uid root.
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60 clockdiff is part of iputils package.
61iputils s20180629 CLOCKDIFF(8)