NTPD.CONF(5) OpenBSD Programmer's Manual NTPD.CONF(5)NAMEntpd.conf - Network Time Protocol daemon configuration file
DESCRIPTION
This manual page describes the format of the ntpd(8) configuration file.
ntpd.conf has the following format:
Empty lines and lines beginning with the `#' character are ignored.
Keywords may be specified multiple times within the configuration file.
They are as follows:
listen on address
Specify a local IP address or a hostname the ntpd(8) daemon
should listen on. If it appears multiple times, ntpd(8) will
listen on each given address. If `*' is given as an address,
ntpd(8) will listen on all local addresses. ntpd(8) does not
listen on any address by default. For example:
listen on *
or
listen on 127.0.0.1
listen on ::1
sensor device [correction microseconds] [weight weight-value] [refid
string]
Specify a timedelta sensor device ntpd(8) should use. The sensor
can be specified multiple times: ntpd(8) will use each given
sensor that actually exists. Non-existent sensors are ignored.
If `*' is given as device name, ntpd(8) will use all timedelta
sensors it finds. ntpd(8) does not use any timedelta sensor by
default. For example:
sensor *
sensor nmea0
An optional correction in microseconds can be given to compensate
for the sensor's offset. The maximum correction is 127 seconds.
For example, if a DCF77 receiver is lagging 70ms behind actual
time:
sensor udcf0 correction 70000
The optional weight keyword permits finer control over the
relative importance of time sources (servers or sensor devices).
Weights are specified in the range 1 to 10; if no weight is
given, the default is 1. A server with a weight of 5, for
example, will have five times more influence on time offset
calculation than a server with a weight of 1.
An optional reference ID string - up to 4 ASCII characters - can
be given to publish the sensor type to clients. RFC 2030
suggests some common reference identifiers, but new identifiers
"can be contrived as appropriate." If an ID string is not given,
ntpd(8) will use a generic reference ID. For example:
sensor nmea0 refid GPS
server address [weight weight-value]
Specify the IP address or the hostname of an NTP server to
synchronize to. If it appears multiple times, ntpd(8) will try
to synchronize to all of the servers specified. If a hostname
resolves to multiple IPv4 and/or IPv6 addresses, ntpd(8) uses the
first address. If it does not get a reply, ntpd(8) retries with
the next address and continues to do so until a working address
is found. For example:
server 10.0.0.2 weight 5
server ntp.example.org weight 1
To provide redundancy, it is good practice to configure multiple
servers. In general, best accuracy is obtained by using servers
that have a low network latency.
servers address [weight weight-value]
As with server, specify the IP address or hostname of an NTP
server to synchronize to. If it appears multiple times, ntpd(8)
will try to synchronize to all of the servers specified. Should
the hostname resolve to multiple IP addresses, ntpd(8) will try
to synchronize to all of them. For example:
servers pool.ntp.org
FILES
/etc/ntpd.conf default ntpd(8) configuration file
SEE ALSOntpd(8), sysctl(8)HISTORY
The ntpd.conf file format first appeared in OpenBSD 3.6.
OpenBSD 4.9 May 18, 2009 OpenBSD 4.9
