77 lines
1.9 KiB
Groff
77 lines
1.9 KiB
Groff
.\"
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.\" $FreeBSD$
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.\"
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.Dd January 6, 2000
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.Dt NTPTRACE 8
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.Os
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.Sh NAME
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.Nm ntptrace
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.Nd "trace a chain of NTP servers back to the primary source"
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.Sh SYNOPSIS
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.Nm
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.Op Fl vdn
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.Op Fl r Ar retries
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.Op Fl t Ar timeout
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.Op Ar server
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.Sh DESCRIPTION
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The
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.Nm
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utility determines where a given Network Time Protocol (NTP) server gets
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its time from, and follows the chain of NTP servers back to their
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master time source.
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If given no arguments, it starts with
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.Dq localhost .
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.Pp
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Here is an example of the output from
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.Nm :
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.Bd -literal
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% ntptrace
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localhost: stratum 4, offset 0.0019529, synch distance 0.144135
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server2ozo.com: stratum 2, offset 0.0124263, synch distance 0.115784
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usndh.edu: stratum 1, offset 0.0019298, synch distance 0.011993, refid 'WWVB'
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.Ed
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.Pp
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On each line, the fields are (left to right): the host name, the
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host stratum,
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the time offset between that host and the local host
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(as measured by
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.Nm ;
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this is why it is not always zero for
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.Dq localhost ) ,
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the host
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synchronization distance,
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and (only for stratum-1 servers) the reference clock ID.
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All times
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are given in seconds.
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Note that the stratum is the server hop count to the primary source,
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while the synchronization distance is the estimated error
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relative to the primary source.
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These terms are precisely defined in RFC 1305.
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.Pp
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The following options are available:
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.Bl -tag -width indent
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.It Fl d
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Turn on some debugging output.
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.It Fl n
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Turn off the printing of host names; instead, host IP addresses
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are given.
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This may be necessary if a nameserver is down.
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.It Fl r Ar retries
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Set the number of retransmission attempts for each host; the default is 5.
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.It Fl t Ar timeout
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Set the retransmission timeout (in seconds); the default is 2.
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.It Fl v
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Print verbose information about the NTP servers.
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.El
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.Sh SEE ALSO
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.Xr ntpd 8 ,
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.Xr ntpdc 8
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.Rs
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.%A D L Mills
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.%T Network Time Protocol (Version 3)
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.%O RFC1305
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.Re
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.Sh BUGS
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This program makes no attempt to improve accuracy by doing multiple
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samples.
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