Setup NTP Server on Rocky Linux

This article is going to take you through on how to Setup NTP Server on Rocky Linux. NTP is a networking protocol for synchronizing computer clocks across packet-switched, variable-latency data networks. NTP aims to keep all participating computers within a few milliseconds of Coordinated Universal Time (UTC) (UTC).

How to Setup NTP Server on Rocky Linux

• The ntp package is no longer supported in Rocky Linux, and its functionality is now provided by the chronyd (a user-space daemon) in the chrony package. Use the command below to install NTP server.

sudo yum  install chrony

• Next, start and enable chrony service using the command below.

sudo systemctl enable --now chronyd

• It should be up and running, check status using the command below.

systemctl status chronyd

Sample output

● chronyd.service - NTP client/server
   Loaded: loaded (/usr/lib/systemd/system/chronyd.service; enabled; vendor preset: enabled)
   Active: active (running) since Tue 2022-04-19 21:28:22 EAT; 1h 16min ago
     Docs: man:chronyd(8)
           man:chrony.conf(5)
 Main PID: 1041 (chronyd)
    Tasks: 1 (limit: 23385)
   Memory: 1.8M
   CGroup: /system.slice/chronyd.service
           └─1041 /usr/sbin/chronyd

Apr 19 21:28:18 localhost.localdomain systemd[1]: Starting NTP client/server...
Apr 19 21:28:19 localhost.localdomain chronyd[1041]: chronyd version 4.1 starting (+CMDMON +NTP +REFCLOCK +RTC +PRIVDROP +SCFILTER +SIGND +ASYNCDNS +NTS +SECHASH +IPV6 +DEBUG)
Apr 19 21:28:19 localhost.localdomain chronyd[1041]: Frequency -12.608 +/- 0.452 ppm read from /var/lib/chrony/drift
Apr 19 21:28:19 localhost.localdomain chronyd[1041]: Using right/UTC timezone to obtain leap second data
Apr 19 21:28:22 localhost.localdomain systemd[1]: Started NTP client/server.
Apr 19 21:28:39 localhost.localdomain chronyd[1041]: Selected source 162.159.200.123 (2.pool.ntp.org)
Apr 19 21:28:39 localhost.localdomain chronyd[1041]: System clock TAI offset set to 37 seconds
Apr 19 21:29:46 localhost.localdomain chronyd[1041]: Selected source 160.119.216.197 (2.pool.ntp.org)

Configure NTP server on Rocky Linux

• Switch to the nearest server pool by editing NTP config file. Check out the closest server pool to your continent in the NTP pool project.

• Then open the config file with the command below.

sudo nano /etc/chrony.conf

• replace the existing pools

# Specify one or more NTP servers.
pool 2.pool.ntp.org iburst

• with one nearest to you. For example Africa/South Africa;

# Specify one or more NTP servers.

# Use servers from the NTP Pool Project. Approved by Ubuntu Technical Board
# on 2011-02-08 (LP: #104525). See http://www.pool.ntp.org/join.html for
# more information.
#pool 2.pool.ntp.org iburst
server 0.za.pool.ntp.org
server 1.za.pool.ntp.org
server 2.za.pool.ntp.org
server 3.za.pool.ntp.org

• Next uncomment the allow configuration directive and set its value to the network or subnet address from which clients are permitted to connect. e.g.

allow 192.168.0.0/24 

• Save and exit the file.
• Restart the NTP server using the following command to apply changes.

sudo systemctl restart chronyd

Configure Firewall for NTP server clients

• Allow NTP on the firewall

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

• Next reload the firewall to apply the changes

firewall-cmd --reload

Configure NTP Client

• Install NTP on your client system using the command below.

sudo yum install chrony

• Next enable chrony to start on boot.

systemctl enable chronyd

• Then set chrony to act as an NTP client by adding NTP server IP in the /etc/chrony.conf file as shown below.
• Open /etc/chrony.conf file using your favorite text editor.

sudo nano /etc/chrony.conf

• Add your server IP in the format below.

Server 192.168.171.128

• To apply the changes, restart Chrony NTP daemon.

sudo systemctl restart chronyd

• To see the current time sources (NTP server) that chronyd is accessing, use the following command, which should display NTP server address.

chronyc sources

• This brings us to the end of our article, congrats!
• You’ve learnt how to Setup NTP server on Rocky Linux and how to configure a client to use the NTP server for time synchronization.

Read more on NTP Documentation

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