NTPD(8) OpenBSD System Manager's Manual NTPD(8)NAMEntpd - Network Time Protocol daemon
SYNOPSISntpd [-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
validity.
-S Do not set the time immediately at startup. This is the
default.
-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
information on the boot process and enabling daemons.
When ntpd starts up, it reads settings from its configuration file,
typically 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 ALSOdate(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 4.9 February 12, 2009 OpenBSD 4.9
