I was recently working on a Grid Computing project, where I had to install a grid middleware called Globus Toolkit. If you had ever worked on Globus Toolkit, then you might be aware that it uses a security module called Grid Security Infrastructure (GSI), which actually works based on Public Key Infrastructure (PKI). It means, all grid computing related transactions are happened over X.509 digital certificates for authentication and authorization. So it’s quite important to have all the machines that are involved in grid computation to be synchronized with a common time server. That’s probably why I ended up in installing NTP on those machines.
To the point, I’m going to share how to install and configure NTP on CentOS machines.
What is NTP?
NTP stands for Network Time Protocol, which actually send time signals over the network to synchronize NTP clients (the description is enough for now and you can find better explanation at ntp.org). NTP can be installed using ‘yum‘ command.
Install NTP
#yum install ntp .................... Installed: ntp.x86_64 0:4.2.6p5-2.el6.centos Dependency Installed: ntpdate.x86_64 0:4.2.6p5-2.el6.centos Complete!
Configure ‘ntpd’ to start during the boot
# chkconfig ntpd on
Update NTP
# ntpdate pool.ntp.org
Start ‘ntpd’ daemon
# service ntpd start or # /etc/init.d/ntpd start
NTPSTAT
You can also run ntpstat after configuring ‘server’ in /etc/ntp.conf.
# ntpstat unsynchronised time server re-starting polling server every 8 s
Configure NTP
# vim /etc/ntp.conf
and add the below lines…
server 0.centos.pool.ntp.org server 1.centos.pool.ntp.org server 2.centos.pool.ntp.org server 3.centos.pool.ntp.org
By default, the public NTP pool servers (for CentOS) would have been added to the ntp.conf file. The ‘server’ attribute can be used to add your organization’s NTP server as well.
For example,
server ntp.yourorganization.org
That’s it!
