MAN page from Trustix iputils-0.0.20020927-8tr.i586.rpm
Section: System Manager's Manual: iputils (8)
Updated: 27 September 2002Index
clockdiff - measure clock difference between hosts
clockdiff [ -o] [ -o1] destination
clockdiff Measures clock difference between us anddestination with 1 msec resolution using ICMP TIMESTAMPpackets or, optionally, IP TIMESTAMP optionoption added to ICMP ECHO.
- Use IP TIMESTAMP with ICMP ECHO instead of ICMP TIMESTAMPmessages. It is useful with some destinations, which do not supportICMP TIMESTAMP (f.e. Solaris <2.4).
- Slightly different form of -o, namely it uses three-termIP TIMESTAMP with prespecified hop addresses instead of four term one.What flavor works better depends on target host. Particularly,-o is better for Linux.
- Some nodes (Cisco) use non-standard timestamps, which is allowedby RFC, but makes timestamps mostly useless.
- Some nodes generate messed timestamps (Solaris>2.4), whenrun xntpd. Seems, its IP stack uses a corrupted clock source,which is synchronized to time-of-day clock periodically and jumpsrandomly making timestamps mostly useless. Good news is that you canuse NTP in this case, which is even better.
- clockdiff shows difference in time modulo 24 days.
 ICMP ECHO,RFC0792, page 14.
 ICMP TIMESTAMP,RFC0792, page 16.
 IP TIMESTAMP option,RFC0791, 3.1, page 16.
clockdiff was compiled byAlexey Kuznetsov<kuznetAATTms2.inr.ac.ru>. It was based on code borrowedfrom BSD timed daemon.
clockdiff requires CAP_NET_RAWIO capabilityto be executed. It is safe to be used as set-uid root.
clockdiff is part of iputils packageand the latest versions are available in source form for anonymous ftpftp://ftp.inr.ac.ru/ip-routing/iputils-current.tar.gz.
- SEE ALSO
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