How to Setup Local NTP server in Linux 7

Network Time Protocol (NTP) – This is a protocol which runs over port 123 UDP at

Transport Layer and allows computers to synchronize time over networks for an

accurate time. This is majorly used when working with the cluster system, Oracle RAC,

Master-Slave setups.

We will see in this post how to set up the NTP Server and Client

Part 1- NTP server Preparation

1) Install ntp package: We need to install the ntp if not already available.

yum install ntp

2) Edit the NTP configuration

vi /etc/ntp.conf

3) Comment pool for server sync (Used in case of internet)

and Add local server 127.127.1.0

# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
#server 0.rhel.pool.ntp.org iburst
#server 1.rhel.pool.ntp.org iburst
#server 2.rhel.pool.ntp.org iburst
#server 3.rhel.pool.ntp.org iburst
server 127.127.1.0

4) Restrict to a range of IP to which access is required.

Add below line in etc/ntp.conf

restrict 192.168.56.0 mask 255.255 255.0 notrap

logfile /var/log/ntpservice.log

5) Enable NTP service over the firewall

firewall-cmd --add-service=ntp --permanent

firewall-cmd --reload

6) Start NTPD service and enable it to start in case of a reboot.

systemctl start ntpd

systemctl enable ntpd

systemctl status ntpd

7) Verify the NTP is using which server ( In my case it is local)

[root@oel7 ~]# ntpq -p

remote refid st t when poll reach delay offset jitter

==============================================================================

*LOCAL(0) .LOCL. 5 l 8 64 7 0.000 0.000 0.000

Part 2- NTP Client Preparation

We can have the client as Linux, Windows, or Mac OS.

Setup client on Linux

We need to make sure NTP is installed or else we need to install it.

1) yum install ntp

2) Edit the ntp configuration file and setup to enable sync via NTP server configured earlier.

We have to add an entry of our NTP server IP/hosts from where the client would sync.

Comment the other pool entries.

vi /etc/ntp.conf

# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
#server 0.centos.pool.ntp.org iburst
#server 1.centos.pool.ntp.org iburst
#server 2.centos.pool.ntp.org iburst
#server 3.centos.pool.ntp.org iburst
server 192.168.56.110

4) Sync the time before starting NTP service. It is done via hostname/IP of you NTP server
ntpdate -q 192.168.56.110

5) start ntp service
systemctl ntpd start

Now client is in sync with NTP server.

Setup client on Windows

Starting with Windows, Go to the Control Panel "Date and Time" option contains

an Internet Time tab which allows choosing an NTP server and turning time

synchronization on or off.

Update the entry with host/Ip or NTP server.

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