NTP, Network Time Protocol, it is an Internet protocol used to synchronize the clocks of computers or servers to some NTP server on internet or intranet. In CentOS, it is very easy to install and configure the ntp client.
Install your NTP client using yum command:
[root@server ~]# yum install ntp Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile * addons: ftp.oss.eznetsols.org * base: ftp.oss.eznetsols.org * epel: ftp.cuhk.edu.hk * extras: ftp.oss.eznetsols.org * updates: ftp.oss.eznetsols.org Setting up Install Process Resolving Dependencies --> Running transaction check ---> Package ntp.x86_64 0:4.2.2p1-9.el5.centos.2.1 set to be updated --> Finished Dependency Resolution Dependencies Resolved ===================================================================================== Package Arch Version Repository Size ===================================================================================== Installing: ntp x86_64 4.2.2p1-9.el5.centos.2.1 base 1.3 M Transaction Summary ===================================================================================== Install 1 Package(s) Upgrade 0 Package(s) Total download size: 1.3 M Is this ok [y/N]: y Downloading Packages: ntp-4.2.2p1-9.el5.centos.2.1.x86_64.rpm | 1.3 MB 00:04 Running rpm_check_debug Running Transaction Test Finished Transaction Test Transaction Test Succeeded Running Transaction Installing : ntp 1/1 Installed: ntp.x86_64 0:4.2.2p1-9.el5.centos.2.1 Complete!
Configure your ntp.conf file and pointing to your NTP server
[root@server ~]# vi /etc/ntp.conf
server 0.centos.pool.ntp.org //set this to your primary NTP server - Line 17 server 1.centos.pool.ntp.org //set this to your Secondary NTP server (Optional) - Line 18 server 2.centos.pool.ntp.org //set this to your tertiary NTP server(Optional) - Line 19
As for example :
server ntp1.server.local server ntp2.server.local
Restart your ntp client using below command:
[root@server ~]# service ntpd restart
or
[root@server ~]# /etc/init.d/ntpd restart
Test your ntp client status whether properly configured or not by running below command:
[root@server ~]# ntpq -p