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.\" $OpenBSD: ntpd.conf.5,v 1.9 2004/11/08 19:09:19 otto Exp $
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.\"
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.\" Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
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.\"
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.\" Permission to use, copy, modify, and distribute this software for any
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.\" purpose with or without fee is hereby granted, provided that the above
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.\" copyright notice and this permission notice appear in all copies.
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.\"
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.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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.\" WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER IN
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.\" AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
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.\" OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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.\"
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.Dd June 17, 2004
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.Dt NTPD.CONF 5
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.Os
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.Sh NAME
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.Nm ntpd.conf
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.Nd Network Time Protocol daemon configuration file
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.Sh DESCRIPTION
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This manual page describes the format of the
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.Xr ntpd 8
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configuration file.
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It has the following format:
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.Pp
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Empty lines and lines beginning with the
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.Sq #
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character are ignored.
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.Pp
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Keywords may be specified multiple times within the configuration file.
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They are as follows:
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.Bl -tag -width Ds
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.It Ic listen on Ar address
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Specify a local IP address or a hostname the
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.Xr ntpd 8
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daemon should listen on.
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If it appears multiple times,
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.Xr ntpd 8
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will listen on each given address.
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If
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.Sq *
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is given as an address,
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.Xr ntpd 8
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will listen on all local addresses.
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.Xr ntpd 8
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does not listen on any address by default.
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For example:
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.Bd -literal -offset indent
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listen on *
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listen on 127.0.0.1
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listen on ::1
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.Ed
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.It Ic server Ar address
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Specify the IP address or the hostname of an NTP
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server to synchronize to.
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If it appears multiple times,
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.Xr ntpd 8
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will try to synchronize to all of the servers specified.
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If a hostname resolves to multiple IPv4 and/or IPv6 addresses,
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.Xr ntpd 8
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uses the first address.
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If it does not get a reply,
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.Xr ntpd 8
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retries with the next address and continues to do so until a working address
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is found.
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For example:
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.Bd -literal -offset indent
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server 10.0.0.2
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server ntp.example.org
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.Ed
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.Pp
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To provide redundancy, it is good practice to configure multiple servers.
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In general, best accuracy is obtained by using servers that have a low
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network latency.
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.It Ic servers Ar address
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As with
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.Cm server ,
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specify the IP address or hostname of an NTP server to synchronize to.
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If it appears multiple times,
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.Xr ntpd 8
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will try to synchronize to all of the servers specified.
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Should the hostname resolve to multiple IP addresses,
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.Xr ntpd 8
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will try to synchronize to all of them.
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For example:
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.Bd -literal -offset indent
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servers pool.ntp.org
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.Ed
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.El
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.Sh FILES
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.Bl -tag -width "/etc/ntpd.confXXX" -compact
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.It Pa /etc/ntpd.conf
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default
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.Xr ntpd 8
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configuration file
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.El
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.Sh SEE ALSO
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.Xr ntpd 8
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.Sh HISTORY
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The
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.Nm
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file format first appeared in
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.Ox 3.6 .
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