How to Configure Network Time Protocol NTP Server in CentOS RHEL Fedora

Articles CentOS Configuration fedora How To How To's NTP Server

We have two Linux Machines one machine is Server  and one machine is Client

Server Machine 192.168.1.50 baber

Cleint Machine  192.168.1.60 farrukh

Server side configuration on CentOS /RHEL /Fedora

root@localhost# vi /etc/ntp.conf
# Permit time synchronization with our time source, but do not
# permit the source to query or modify the service on this system.
 restrict default kod nomodify notrap nopeer noquery
# Permit all access over the loopback interface. This could
 # be tightened as well, but to do so would effect some of
 # the administrative functions.
 restrict 127.0.0.1
# Hosts on local network are less restricted.
 #restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap
# Use public servers from the pool.ntp.org project.
 # Please consider joining the pool (http://www.pool.ntp.org/join.html).
### Edited By Babar Zahoor Jun 16 2009 ###
 #server 0.centos.pool.ntp.org
 #server 1.centos.pool.ntp.org
 #server 2.centos.pool.ntp.org
#broadcast 192.168.1.255 key 42 # broadcast server
 #broadcastclient # broadcast client
 #broadcast 224.0.1.1 key 42 # multicast server
 #multicastclient 224.0.1.1 # multicast client
 #manycastserver 239.255.254.254 # manycast server
 #manycastclient 239.255.254.254 key 42 # manycast client
# Undisciplined Local Clock. This is a fake driver intended for backup
 # and when no outside source of synchronized time is available.
########## for server use this and on clients comment this and use server serverIP ##################
server 127.127.1.0 # local clock
#fudge 127.127.1.0 stratum 10
# Drift file. Put this in a directory which the daemon can write to.
 # No symbolic links allowed, either, since the daemon updates the file
 # by creating a temporary in the same directory and then rename()’ing
 # it to the file.
 # driftfile /var/lib/ntp/drift
# Key file containing the keys and key identifiers used when operating
 # with symmetric key cryptography.
 # Specify the key identifiers which are trusted.
 # trustedkey 4 8 42
# Specify the key identifier to use with the ntpdc utility.
 # requestkey 8
# Specify the key identifier to use with the ntpq utility.
 #controlkey 8
 keys /etc/ntp/keys
save quit.
[root@baber ~]#
 [root@baber ~]# /etc/init.d/ntpd start
 [root@baber ~]# chkconfig –level 235 ntpd on

Client Side Configuration on NTP Client Machines

[root@farrukh ~]# vim ntp.conf
 # Permit time synchronization with our time source, but do not
 # permit the source to query or modify the service on this system.
 restrict default kod nomodify notrap nopeer noquery
# Permit all access over the loopback interface. This could
 # be tightened as well, but to do so would effect some of
 # the administrative functions.
 #restrict 127.0.0.1
 #estrict -6 ::1
# Hosts on local network are less restricted.
 #restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap
# Use public servers from the pool.ntp.org project.
 # Please consider joining the pool (http://www.pool.ntp.org/join.html).
server 192.168.1.50 ### add this line on second server ###
#server 0.centos.pool.ntp.org
 #server 1.centos.pool.ntp.org
 #server 2.centos.pool.ntp.org
#broadcast 192.168.1.255 key 42 # broadcast server
 #broadcastclient # broadcast client
 #broadcast 224.0.1.1 key 42 # multicast server
 #multicastclient 224.0.1.1 # multicast client
 #manycastserver 239.255.254.254 # manycast server
 #manycastclient 239.255.254.254 key 42 # manycast client
# Undisciplined Local Clock. This is a fake driver intended for backup
 # and when no outside source of synchronized time is available.
#server 127.127.1.0 # local clock ##### #####
 #fudge 127.127.1.0 stratum 10
# Drift file. Put this in a directory which the daemon can write to.
 # No symbolic links allowed, either, since the daemon updates the file
 # by creating a temporary in the same directory and then rename()’ing
 # it to the file.
 driftfile /var/lib/ntp/drift
# Key file containing the keys and key identifiers used when operating
 # with symmetric key cryptography.
 keys /etc/ntp/keys
# Specify the key identifiers which are trusted.
 #trustedkey 4 8 42
# Specify the key identifier to use with the ntpdc utility.
 #requestkey 8
# Specify the key identifier to use with the ntpq utility.
 #controlkey 8
save & exit
[root@farrukh ~]# /etc/init.d/ntpd start
 [root@farrukh ~]# chkconfig –level 235 ntpd on
[root@farrukh ~]# ntpdate -u 192.168.1.50
[root@farrukh ~]# watch ntpq -p -n
[root@baber ~]# watch ntpq -p -n