Network Time Protocol

Configuring NTP on Linux Server

Network Time Protocol, NTP is a service that can query other computers over the network
and synchronize the computer’s clock to the server’s time.

Steps
——–

1) Connect to server using SSH

2) Install NTP. Download rpm from rpmfind.net for the relevant Redhat release.
3) Create the backup of existing /etc/ntp.conf file.
mv /etc/ntp.conf /etc/ntp.conf.bkp

4) Create a new /etc/ntp.conf file with following contents.

——————————–

server 127.127.1.0 # local clock
fudge 127.127.1.0 stratum 10

# servers added by Zed www.bldrdoc.gov/timefreq/service/time-servers.html
server 129.6.15.28
server 129.6.15.29
server 63.149.208.50
server 132.163.4.101
server 132.163.4.102
server 132.163.4.103
server 128.138.140.44
server 192.43.244.18
server 131.107.1.10
server 216.200.93.8
server 208.184.49.9
server 207.126.103.204
server 207.200.81.113
server 205.188.185.33

driftfile /etc/ntp/drift
multicastclient # listen on default 224.0.1.1
broadcastdelay 0.008

#
# Authentication delay. If you use, or plan to use someday, the
# authentication facility you should make the programs in the auth_stuff
# directory and figure out what this number should be on your machine.
#
authenticate no

—————————–

5) Create the separate ticker file /etc/ntp/step-tickers that contains the list of time servers. Use the following command to create the step-tickers file.
awk ‘/^server/ {print $2}’ /etc/ntp.conf | grep -v ‘127.127.1.0′ > /etc/ntp/step-tickers

6) Change the timezone of the server.

ln -sf /usr/share/zoneinfo/GMT /etc/localtime

7) Edit /etc/sysconfig/clock and make sure it has the below entries. If not change it.

ZONE=”GMT”
UTC=true
ARC=false

Before starting the service, synchronize your clock using one of the servers with ntpdate command.
ntpdate -u nist1.datum.com

9) Start the NTPD daemon.
/etc/rc.d/init.d/ntpd start

10) Check the configuration using ntpq -p command.

11) Configure your server to start NTPD at startup.
chkconfig –level 345 ntpd on