.TH NTPD 8 "$Mdocdate: November 10 2007 $" ""
.SH NAME
\fBntpd\fP
\- "Network Time Protocol daemon"
.SH SYNOPSIS
.br
\fBntpd\fP
[\fB\-dnSsv\fP]
[\fB\-f\fP \fIfile\fP]
.SH DESCRIPTION
The
\fBntpd\fP
daemon synchronizes the local clock to one or more remote NTP servers
or local timedelta sensors.
\fBntpd\fP
can also act as an NTP server itself,
redistributing the local time.
It implements the Simple Network Time Protocol version 4,
as described in RFC 2030,
and the Network Time Protocol version 3,
as described in RFC 1305.

\fBntpd\fP
uses the
\fBadjtime\fP(2)
system call to correct the local system time without causing time jumps.
Adjustments larger than 128ms are logged using
\fBsyslog\fP(3)
with LOG_INFO priority.
The threshold value is chosen to avoid having local clock drift
thrash the log files.
Should
\fBntpd\fP
be started with the
\fB\-d\fP
option, all calls to
\fBadjtime\fP(2)
will be logged.

When
\fBntpd\fP
starts up, it reads settings from a configuration file,
typically
\fBntpd.conf\fP(5).

The options are as follows:
.TP
\fB\-d\fP
Do not daemonize.
If this option is specified,
\fBntpd\fP
will run in the foreground and log to
.IR stderr .
.TP
\fB\-f\fP \fIfile\fP
Use
\fIfile\fP
as the configuration file,
instead of the default
\fI/etc/openntpd/ntpd.conf\fP.
.TP
\fB\-n\fP
Configtest mode.
Only check the configuration file for validity.
.TP
\fB\-S\fP
Do not set the time immediately at startup.
This is the default.
.TP
\fB\-s\fP
Set the time immediately at startup if the local clock is off by more
than 180 seconds.
Allows for a large time correction,
eliminating the need to run
\fBrdate\fP(8)
before starting
\fB.\fP
.TP
\fB\-v\fP
This option allows
\fBntpd\fP
to send DEBUG priority messages to syslog.

When
\fBntpd\fP
receives a
.BR SIGINFO
signal, it will write its peer and sensor status to syslog.
.SH FILES
.TP
.B /etc/openntpd/ntpd.conf
default
\fBntpd\fP
configuration file
.TP
.B /var/lib/openntpd/ntpd.drift
drift file, written by
\fBntpd\fP
periodically and used at startup to get the initial clock drift
.SH SEE ALSO
\fBdate\fP(1),
\fBadjfreq\fP(2),
\fBadjtime\fP(2),
\fBntpd.conf\fP(5),
\fBrdate\fP(8),
\fBtimed\fP(8)

, \fINetwork Time Protocol (Version 3)\fP, March 1992.

, \fISimple Network Time Protocol (SNTP) Version 4\fP, October 1996.
.SH HISTORY
The
\fBntpd\fP
program first appeared in
OpenBSD 3.6 .