How to configure NTP servers in Linux?
-
To configure two ntp servers:
On each of the two ntp servers, add "server 127.127.1.0 # local clock" to the file /etc/ntp.conf:
# vi /etc/ntp.conf
server 127.127.1.0 # local clock
Set the date/time on both servers (replace xxxxxx with the appropriate value):
# date xxxxxx
Switch ntp ON for init levels 3 & 5
# chkconfig --level 35 ntpd on
Manually start ntp:
# service ntpd start
On all clients:
Create a cron job to make the clients synchronise with the ntp servers every hour:# crontab -e
00 0-23 * * * /usr/sbin/ntpupdate <ip_address1> <ip_address2>
Where <ip_address1> <ip_address2> are the IP addresses of the two ntp servers you have just configured.
It is also possible to use the hostname of the two ntp servers as opposed to their IP addresses as above, in case IP addresses change. For example:
# crontab -e
00 0-23 * * * /usr/sbin/ntpupdate <hostname1> <hostname2>
To check status of ntp:
# ntpq -p
Many other ntpq options are available:
# ntpq ntpq> help Commands available: addvars associations authenticate cl clearvars clocklist clockvar cooked cv debug delay exit help host hostnames keyid keytype lassociations lopeers lpassociations lpeers mreadlist mreadvar mrl mrv ntpversion opeers passociations passwd peers poll pstatus quit raw readlist readvar rl rmvars rv showv # ntpq -p -n remote refid st t when poll reach delay offset jitter ============================================================================== *127.127.1.0 LOCAL 10 l 3 64 377 0.000 0.000 0.001
© Lightnetics 2024