NTPd – NTP Daemon Program
Last Updated on 2025-01-27 16:48 by Sture
Description:
The ntpd utility is an operating system daemon which sets and maintains the system time of day in synchronization with Internet standard time-servers. It is a complete implementation of the Network Time Protocol (NTP) version 4, as defined by RFC-5905, but also retains compatibility with version 3, as defined by RFC-1305, and versions 1 and 2, as defined by RFC-1059 and RFC-1119, respectively.
Prerequisites
To follow along, make sure that your FreeBSD server has a fully configured Internet access.
Stop the ntpd daemon
Stop the ntpd daemon if it is running with:
user@freebsdsrv:~ $ sudo service ntpd stop [enter]
Stopping ntpd.
Waiting for PIDS: 1484.
user@freebsdsrv:~ $Set the date and time via NTP, using this command:
# user@freebsdsrv:~ $ sudo ntpdate -v -b pool.ntp.org [enter]
27 Jan 16:15:43 ntpdate[4802]: ntpdate 4.2.8p18-a (1)
27 Jan 16:15:50 ntpdate[4802]: step time server 192.36.143.130 offset -0.000046 sec
user@freebsdsrv:~ $N.B.: The ntp server “pool.ntp.org” is recommended by ntp.org. You can also select another one, check out http://www.ntp.org for details.
Default operating system daemon settings
List the defaults for ntpd with:
user@freebsdsrv:~ $ cat /etc/defaults/rc.conf | grep ntp [enter]
ntpdate_enable="NO" # Run ntpdate to sync time on boot (or NO).
ntpdate_program="/usr/sbin/ntpdate" # path to ntpdate, if you want a different one.
ntpdate_flags="-b" # Flags to ntpdate (if enabled).
ntpdate_config="/etc/ntp.conf" # ntpdate(8) configuration file
ntpdate_hosts="" # Whitespace-separated list of ntpdate(8) servers.
ntpd_enable="NO" # Run ntpd Network Time Protocol (or NO).
ntpd_program="/usr/sbin/ntpd" # path to ntpd, if you want a different one.
ntpd_config="/etc/ntp.conf" # ntpd(8) configuration file
ntpd_sync_on_start="NO" # Sync time on ntpd startup, even if offset is high
ntpd_flags="" # Additional flags to ntpd
ntp_src_leapfile="/etc/ntp/leap-seconds"
# Initial source for ntpd leapfile
ntp_db_leapfile="/var/db/ntpd.leap-seconds.list"
ntp_leapfile_sources="https://hpiers.obspm.fr/iers/bul/bulc/ntp/leap-seconds.list https://data.iana.org/time-zones/tzdb/leap-seconds.list"
ntp_leapfile_fetch_opts="-mq" # Options to use for ntp leapfile fetch,
ntp_leapfile_expiry_days=30 # Check for new leapfile 30 days prior to
ntp_leapfile_fetch_verbose="NO" # Be verbose during NTP leapfile fetch
user@freebsdsrv:~ $Enable start server boot
Enable start and set flags of the ntpd utility at boot time with:
user@freebsdsrv:~ $ sudo sysrc ntpd_enable="YES" ntpd_sync_on_start="YES" ntp_leapfile_fetch_verbose="YES" [enter]
ntpd_enable: YES -> YES
ntpd_sync_on_start: NO -> YES
ntp_leapfile_fetch_verbose: NO -> YES
user@freebsdsrv:~ $Configure NTPd
The /etc/ntp.conf configuration file is read at initial startup by the ntpd(8) daemon in order to specify the synchronization sources, modes and other related information.
Update file /etc/ntp.conf to use the Swedish public NTP server with:
user@freebsdsrv:~ $ sudo sh -c "sed -i -e 's/0.freebsd.pool.ntp.org/0.se.pool.ntp.org/' /etc/ntp.conf" ; sudo sh -c "sed -i -e 's/2.freebsd.pool.ntp.org/1.se.pool.ntp.org/' /etc/ntp.conf" ; cat /etc/ntp.conf | grep se.pool.ntp.org [enter]
pool 0.se.pool.ntp.org iburst
pool 1.se.pool.ntp.org iburst
user@freebsdsrv:~ $The drift file is by default /var/db/ntp/ntpd.drift.
Create an empty file, /var/db/ntp/ntpd.drift, with:
user@freebsdsrv:~ $ sudo touch /var/db/ntp/ntpd.drift; sudo chown ntpd:ntpd /var/db/ntp/ntpd.drift ; ls -l /var/db/ntp/ntpd.drift [enter]
-rw-r--r-- 1 ntpd ntpd 9 Jan 27 16:22 /var/db/ntp/ntpd.drift
user@freebsdsrv:~ $Download the current leap-seconds.list file with:
user@freebsdsrv:~ $ sudo rm /var/db/ntpd.leap-seconds.list ; sudo service ntpd fetch [enter]
ntp_src_leapfile version is 3929093563 expires 3960057600
ntp_db_leapfile version is 0 expires 0
replacing /var/db/ntpd.leap-seconds.list with /etc/ntp/leap-seconds
user@freebsdsrv:~ $Manually start NTPd
Start the Network Time Protocol (NTP) daemon, with this command:
user@freebsdsrv:~ $ sudo service ntpd start [enter]
Starting ntpd.
user@freebsdsrv:~ $Verify the NTPd setup with:
user@freebsdsrv:~ $ cat /var/log/messages | grep ntpd [enter]...
Jan 27 16:27:29 freebsdsrv ntpd[11450]: ----------------------------------------------------
Jan 27 16:27:29 freebsdsrv ntpd[11450]: ntp-4 is maintained by Network Time Foundation,
Jan 27 16:27:29 freebsdsrv ntpd[11450]: Inc. (NTF), a non-profit 501(c)(3) public-benefit
Jan 27 16:27:29 freebsdsrv ntpd[11450]: corporation. Support and training for ntp-4 are
Jan 27 16:27:29 freebsdsrv ntpd[11450]: available at https://www.nwtime.org/support
Jan 27 16:27:29 freebsdsrv ntpd[11450]: ----------------------------------------------------
Jan 27 16:27:29 freebsdsrv ntpd[11451]: leapsecond file ('/var/db/ntpd.leap-seconds.list'): good hash signature
Jan 27 16:27:29 freebsdsrv ntpd[11451]: leapsecond file ('/var/db/ntpd.leap-seconds.list'): loaded, expire=2025-06-28T00:00:00Z last=2017-01-01T00:00:00Z ofs=37
user@freebsdsrv:~ $NTP is a very cautious standard. It will report its stratum to 16 (the worst possible) until it’s certain it’s in sync. This can take a few minutes to a few hours.
ntpq – standard NTP query program
The ntpq utility program is used to query NTP servers to monitor NTP operations and performance, requesting information about the current state and/or changes in that state.
Print a list of the peers known to the server as well as a summary of their state:
user@freebsdsrv:~ $ ntpq --peers localhost [enter]
remote refid st t when poll reach delay offset jitter
==============================================================================
0.se.pool.ntp.o .POOL. 16 p - 64 0 0.000 +0.000 0.000
1.se.pool.ntp.o .POOL. 16 p - 64 0 0.000 +0.000 0.000
-sth2.ntp.netnod .PPS. 1 u 50 64 377 14.003 +0.642 0.117
+h-85-24-226-221 194.58.204.20 2 u 46 64 377 2.633 +0.659 0.144
*time100.stupi.s .PPS. 1 u 47 64 377 14.014 +0.466 0.107
+svl1.ntp.netnod .PPS. 1 u 44 64 377 18.632 +0.450 0.099
-h-98-128-175-45 194.58.200.20 2 u 40 64 377 2.168 +0.517 0.177
user@freebsdsrv:~ $N.B.: Waiting for “st” to drop to 2 (since those should be stratum 2 servers) before the server is used for time sync of local computers.
ntpq Help
user@freebsdsrv:~ $ ntpq -? [enter]
ntpq - standard NTP query program - Ver. 4.2.8p17
Usage: ntpq [ - [] | --[{=| }] ]... [ host ...]
Flg Arg Option-Name Description
-4 no ipv4 Force IPv4 name resolution
- prohibits the option 'ipv6'
-6 no ipv6 Force IPv6 name resolution
- prohibits the option 'ipv4'
-c Str command run a command and exit
- may appear multiple times
-d no debug-level Increase debug verbosity level
- may appear multiple times
-D Num set-debug-level Set the debug verbosity level
- may appear multiple times
-i no interactive Force ntpq to operate in interactive mode
- prohibits these options:
command
peers
-n no numeric numeric host addresses
no old-rv Always output status line with readvar
-p no peers Print a list of the peers
- prohibits the option 'interactive'
-r KWd refid Set default display type for S2+ refids
-u no unconnected Use unconnected UDP to communicate with ntpd (default on Windows)
-w no wide Display the full 'remote' value
opt version output version information and exit
-? no help display extended usage information and exit
-! no more-help extended usage information passed thru pager
-> opt save-opts save the option state to a config file
-< Str load-opts load options from a config file
- disabled as '--no-load-opts'
- may appear multiple times
Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.
The following option preset mechanisms are supported:
- reading file $HOME/.ntprc
- reading file ./.ntprc
- examining environment variables named NTPQ_*
The valid "refid" option keywords are:
hash ipv4
or an integer from 0 through 1
Please send bug reports to: <https://bugs.ntp.org, bugs@ntp.org>
user@freebsdsrv:~ $Documentation
Documentation in HTML format for the NTP server can be found in: /usr/share/doc/ntp/.