How to install, configure and manage NTP to synchronize the system clock on CentOS Linux

 

In this tutorial we will learn how to install, configure and use NTP to synchronize the system clock on CentOS.

Tutorial Topology :

Working Internet Connection


Installation :

To install NTP, type the following command :

yum install ntp


Configuration :

To ensure that the NTP client start at boot time, let add it into config for level 3, 4 and 5 by typing the following command :

chkconfig --level 345 ntpd on


Synchronization :

To synchronize the system clock with the Internet (such as NTP.org), type the following command :

ntpdate 0.centos.pool.ntp.org


Manage the NTP Service :

To start the NTP service, type the following command:

/sbin/service ntpd start

To restart the NTP service, type the following command:

/sbin/service ntpd restart

To stop the NTP service, type the following command:

/sbin/service ntpd stop


Miscellaneous :

You could also setup a cron with crontab to run the ntpdate at a specific interval at your convenience. Don’t forget to make sure that you have a working Internet Connection and that proper firewall rule have been added to allow the traffic, otherwise it might not work properly.