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

NAME
     ntpd - Network Time Protocol daemon

SYNOPSIS
     ntpd [-dnSsv] [-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.

     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.

     -n          Configtest mode.  Only check the configuration file for va-
                 lidity.

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

     -s          Set the time immediately at startup.  Allows for a large time
                 correction, eliminating the need to run rdate(8).

     -v          This option allows ntpd to send DEBUG priority messages to
                 syslog.

     ntpd uses the adjtime(2) system call to correct the local system time
     without causing time jumps.  Adjustments of 32ms and greater are logged
     using syslog(3).  The threshold value is chosen to avoid having local
     clock drift thrash the log files.  Should ntpd be started with the -d or
     -v option, all calls to adjtime(2) will be logged.

     After the local clock is synchronized, ntpd adjusts the clock frequency
     using the adjfreq(2) system call to compensate for systematic drift.

     ntpd is usually started at boot time, and can be enabled by setting
     ntpd_flags in /etc/rc.conf.local.  See rc(8) and rc.conf(8) for more in-
     formation on the boot process and enabling daemons.

     When ntpd starts up, it reads settings from its configuration file, typi-
     cally ntpd.conf(5), and its initial clock drift from /var/db/ntpd.drift.
     Clock drift is periodically written to the drift file thereafter.

     When ntpd receives a SIGINFO signal, it writes its peer and sensor status
     to syslog(3).

FILES
     /etc/ntpd.conf         Default configuration file.
     /var/db/ntpd.drift     Drift file.

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 4.7                    February 12, 2009                             2
