NTP is installed by default on FreeBSD.
When the NTP daemon is running and synced with external time sources, you can configure your Intranet PCs and connected devices to sync their time with it.
The daemon can be enabled at boot time by adding to /etc/rc.conf
ntpd_enable="YES"
ntpd_sync_on_start="YES"
By default ntpd will use NTP time servers assigned via the 0.freebsd.pool.ntp.org pool.
To configure the the NTP daemon to instead use your desired upstream time servers, edit /etc/ntp.conf
Comment out to disable the following line:
pool 0.freebsd.pool.ntp.org iburst
Add your preferred public time servers as well as access control directives to the bottom of the configuration:
server clock.uregina.ca server time.nrc.ca server ntp.torix.ca server clock.sjc.he.net server clock.fmt.he.net server clock.nyc.he.net restrict 192.168.0.0 mask 255.255.0.0 restrict 2001:xxxx:xxxx:xxxx:: mask ffff:ffff:ffff:ffff::
NOTE: ntpd will by default bind to all available interfaces in the system. On your firewall do not permit ingress NTP connections (port UDP 123) from the Internet to your server unless you have a specific need to do so.
When choosing public NTP servers to configure, select the ones that is geographically close and review its usage policy. Web search for 'public ntp stratum 1' + 'your country'
minpoll and maxpolI values default to: minpoll 6 (64 seconds) and maxpoll 10 (1024 seconds)
Should you desire to use different min and max polling intervals, this chart displays the calculated times of all valid values (4 - 17)
Adjust the server line(s) in /etc/ntp.conf to include your desired values.
server time.nrc.ca minpoll 8 maxpoll 13
NTP by default logs to the default system syslog facility.
To specify a log file, add the logfile option to /etc/ntp.conf
logfile /var/log/ntpd.log
Start the serviceservice ntpd start
To view the current status of the running NTP daemon:ntpq -p
remote refid st t when poll reach delay offset jitter ============================================================================== *CLOCK.UREGINA.C .GPS. 1 u 2 512 377 26.274 -0.109 0.618 -time12.nrc.ca 132.246.11.231 2 u 41 512 377 65.282 -1.345 0.317 -ntp2.torix.ca .PTP0. 1 u 38 512 377 49.414 +3.636 0.407 +clock.sjc.he.ne .CDMA. 1 u 273 512 337 47.117 +1.830 0.881 +clock.fmt.he.ne .CDMA. 1 u 67 512 377 47.229 +2.239 0.541 -clock.nyc.he.ne 127.67.113.92 2 u 70 512 377 76.958 +5.716 3.804
Columns Defined:
* = current time source
+ = source selected, included in final set
o = source selected, Pulse Per Second (PPS) used
# = backup (more than tos maxclock sources)
– = source discarded by cluster algorithm
x = source discarded, false ticker
. = source discarded by table overflow (not used)
blank = source discarded, high stratum, failed sanity
remote: the time source peer specified in ntp.conf
refid: remote source’s synchronization source
st: stratum level of the source
t: the type of connected time source
l = local (i.e. GPS)
u = unicast (most common type)
m = multicast
b = broadcast
– = netaddr
when: number of seconds passed since last response
poll: polling interval, in seconds, for source
reach: indicates success/failure to reach source, 377 all attempts successful
delay: indicates the roundtrip time, in milliseconds, to receive a reply
offset: indicates the time difference, in milliseconds, between the client server and source
jitter: indicates the difference, in milliseconds, between two samples