Install and Configure NTP Server and Client on AlmaLinux 8

In this article, we want to teach you to Install and Configure NTP Server and Client on AlmaLinux 8.

A ‘network time server’ is a general description of the software on the NTP– Network Time Protocol server which is running on any server/computer platform. It is applied to the network appliance (tray mount, rack, etc), which acquires and uses time from an external source to maintain time within its local internal clock, and then supplies the time to its connected network. This is achieved using the NTP or Network Time Protocol.

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Install and Configure NTP Server and Client on AlmaLinux 8

Install and Configure NTP Server and Client on AlmaLinux 8

Before you start to install NTP on AlmaLinux 8, you need to log in to your server as a non-root user with sudo privileges and set up a basic firewall. To do this, you can follow our article the Initial Server Setup with AlmaLinux 8.

Now follow the steps below to complete this guide.

Install Chrony on AlmaLinux 8

To install NTP on your server, you need to have Chrony installed on your server.

Chrony is an implementation of the Network Time Protocol and is useful in a number of ways.

First of all, check the current time zone of your server with the following command:

timedatectl

Example output:

Output
Time zone: America/New_York (EDT, -0400)

First, update your local package index with the following command:

sudo dnf update -y

Then, install Chrony on AlmaLinux 8 with the following command:

sudo dnf install chrony -y

Start and enable your Chrony service with the commands below:

# sudo systemctl start chronyd 
# sudo systemctl enable chronyd

To verify that your Chrony service is active and running on your server, run the command below:

sudo systemctl status chronyd

Output
chronyd.service - NTP client/server
Loaded: loaded (/usr/lib/systemd/system/chronyd.service; enabled; vendor pre>
Active: active (running) since Mon 2022-04-11 06:59:56 EDT; 10min ago
Docs: man:chronyd(8)
man:chrony.conf(5)
Main PID: 23975 (chronyd)
Tasks: 1 (limit: 11409)
Memory: 1.6M
CGroup: /system.slice/chronyd.service
└─23975 /usr/sbin/chronyd

Configure NTP Server on AlmaLinux 8

The default configuration file for the NTP server is /etc/chrony.conf.

First, you need to open the file with your favorite text editor, here we use vi:

sudo vi /etc/chrony.conf

At the file, comment on the Pool line by adding the # from the beginning of the line.

Add a list of NTP servers close to your location. In my case is the US, you can use the All pool server on the ntppool website:

#pool 2.cloudlinux.pool.ntp.org iburst
server 0.us.pool.ntp.org
server 1.us.pool.ntp.org
server 2.us.pool.ntp.org
server 3.us.pool.ntp.org

Also, you need to Allow NTP client access from the local network. To do this, edit the line below:

# Allow NTP client access from local network. 
allow 192.168.201.0/24

When you are done, save and close the file.

In the next step, you need to set NTP synchronization with the following command:

sudo timedatectl set-ntp true

Restart your Chrony service to apply the changes:

sudo systemctl restart chronyd

Now you can check your NTP server is working or not with the following command:

chronyc sources

Output
MS Name/IP address Stratum Poll Reach LastRx Last sample
===============================================================================
^? ntp.xtom.com 2 6 1 4 +592us[ +592us] +/- 139ms
^? mail.fotiu.com 3 6 1 4 -15ms[ -15ms] +/- 140ms
^? 2605:6400:d814::ad18 2 6 1 4 -2515us[-2515us] +/- 111ms
^? ns1.backplanedns.org 2 6 1 7 +7127us[+7127us] +/- 140ms

At this point, you need to allow NTP service through the AlmaLinux 8 firewall:

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

Reload the firewall to apply the changes:

sudo firewall-cmd --reload

Configure NTP Client

At this point, you need to install the NTP client on a client machine and configure it with the Chrony.

First, you need to set the correct timezone on your client machine:

sudo timedatectl set-timezone America/New_York

Then, install Chrony on your client machine:

sudo dnf install chrony -y

Edit the configuration file /etc/chrony.conf and point to your NTP server.

sudo vi /etc/chrony.conf

#pool 2.fedora.pool.ntp.org iburst 
server your-server-ip-address

When you are done, save and close the file.

Restart your Chrony service to apply the changes:

sudo systemctl restart chronyd

Next, set NTP synchronization:

sudo timedatectl set-ntp true

Enable your Chrony service to start on boot:

sudo systemctl enable chronyd

Now verify your time synchronization:

chronyc sources

Output
MS Name/IP address Stratum Poll Reach LastRx Last sample 
=============================================================================== 
^* server-ip-address  4 6 37 29 +14us[ +30us] +/- 11ms

Finally, you can check on NTP clients. To do this, log in to your AlmaLinux 8 server and run the command below:

sudo chronyc clients

Output
Hostname NTP Drop Int IntL Last Cmd Drop Int Last
 =============================================================================== 
localhost 0 0 - - - 5 0 10 13 
client-machine-ip  19 0 6 - 67 0 0 - -