NTPD(8)                 OpenBSD System Manager's Manual                NTPD(8)

NAME
     ntpd - Network Time Protocol daemon

SYNOPSIS
     ntpd [-dSs] [-f file]

DESCRIPTION
     The ntpd daemon synchronizes the local clock to one or more remote NTP
     servers or local timedelta sensors.  ntpd 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.

     ntpd uses the adjtime(2) system call to correct the local system time
     without causing time jumps.  Adjustments larger than 128ms are logged us-
     ing syslog(3).  The threshold value is chosen to avoid having local clock
     drift thrash the log files.  Should ntpd be started with the -d option,
     all calls to adjtime(2) will be logged.

     ntpd is usually started at boot time, and can be enabled by setting the
     following in /etc/rc.conf.local:

           ntpd_flags=""

     See rc(8) and rc.conf(8) for more information on the boot process and en-
     abling daemons.

     When ntpd starts up, it reads settings from a configuration file, typi-
     cally ntpd.conf(5).

     The options are as follows:

     -d          Do not daemonize.  If this option is specified, ntpd will run
                 in the foreground and log to stderr.

     -f file     Use file as the configuration file, instead of the default
                 /etc/ntpd.conf.

     -S          Do not set the time immediately at startup.  This is the de-
                 fault.

     -s          Set the time immediately at startup if the local clock is off
                 by more than 180 seconds.  Allows for a large time correc-
                 tion, eliminating the need to run rdate(8) before starting
                 ntpd.

FILES
     /etc/ntpd.conf         default ntpd configuration file
     /var/db/ntpd.drift     drift file, written by ntpd periodically and used
                            at startup to get the initial clock drift

SEE ALSO
     date(1), adjfreq(2), adjtime(2), ntpd.conf(5), rc(8), rc.conf(8),
     rdate(8), timed(8)

     Network Time Protocol (Version 3), RFC 1305, March 1992.

     Simple Network Time Protocol (SNTP) Version 4, RFC 2030, October 1996.

HISTORY
     The ntpd program first appeared in OpenBSD 3.6.

OpenBSD 4.1                      May 26, 2006                                1
