How do I install and configure NTP under CentOS Linux version 5.x or 6.x server to synchronize the system clock?
You can easily install NTP (Network Time Protocol, a means of transmitting time signals over a computer network) using the yum command under Red Hat or CentOS/Fedora Linux server or workstation based systems. You need to install the following packages:
- ntp : ntpd server which continuously adjusts system time and utilities used to query and configure the ntpd daemon.
- ntpdate : Utility to set the date and time via NTP.
- ntp-doc : NTP documentation
Procedure: Setup NTPD on CentOS Linux
Open the terminal or login over the ssh session. You must login as as the root user. Type the following yum command to install ntp
# yum install ntp ntpdate ntp-doc
Turn on service, enter:
# chkconfig ntpd on
Synchronize the system clock with 0.pool.ntp.org server (use this command only once or as required):
# ntpdate pool.ntp.org
Start the NTP server. The following will continuously adjusts system time from upstream NTP server. No need to run ntpdate:
# /etc/init.d/ntpd start
Configure ntpd (optional)
Edit /etc/ntp.conf, enter:
# vi /etc/ntp.conf
Set public servers from the pool.ntp.org project:
server 0.rhel.pool.ntp.org server 1.rhel.pool.ntp.org server 2.rhel.pool.ntp.org