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How to install chrony in Linux

To install Chrony on CentOS, you can use the package manager yum. Here are the steps to install Chrony:

  1. Open a terminal on your CentOS system.
  2. Make sure your system is updated by running the following command:bashCopy codesudo yum update
  3. Install Chrony using the following command:bashCopy codesudo yum install chrony
  4. Once the installation is complete, you can start and enable the Chrony service to ensure it starts automatically on boot:bashCopy codesudo systemctl start chronyd sudo systemctl enable chronyd
  5. Check the status of the Chrony service to ensure it is running:bashCopy codesudo systemctl status chronyd If everything is set up correctly, you should see output indicating that the service is active and running.

Now, Chrony is installed and running on your CentOS system. You can configure Chrony by editing its configuration file located at /etc/chrony.conf. After making any changes to the configuration file, remember to restart the Chrony service:

bashCopy code

sudo systemctl restart chronyd

Make sure to adjust any firewall settings if necessary to allow NTP (Network Time Protocol) traffic if you want your system to synchronize its time with remote NTP servers.

How to configure NTP Server in RedHat / CentOS / Fedora

Introduction

Network Time Protocol (NTP) is a networking protocol for clock synchronization between computer systems over packet-switched, variable-latency data networks. NTP is a protocol designed to synchronize the clocks of computers over a network.

By Default Port # 123

Step 1: Install ntp Package

To configure NTP Server, firstly we need to install the ntp package:

# yum -y install ntp
Loaded plugins: amazon-id, rhui-lb
Resolving Dependencies
--> Running transaction check
---> Package ntp.x86_64 0:4.2.6p5-19.el7_0 will be installed
--> Processing Dependency: ntpdate = 4.2.6p5-19.el7_0 for package: ntp-4.2.6p5-19.el7_0.x86_64
--> Processing Dependency: libopts.so.25()(64bit) for package: ntp-4.2.6p5-19.el7_0.x86_64
--> Running transaction check
---> Package autogen-libopts.x86_64 0:5.18-5.el7 will be installed
---> Package ntpdate.x86_64 0:4.2.6p5-19.el7_0 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

================================================================================================================
 Package                 Arch           Version                  Repository                                Size
================================================================================================================
Installing:
 ntp                     x86_64         4.2.6p5-19.el7_0         rhui-REGION-rhel-server-releases         540 k
Installing for dependencies:
 autogen-libopts         x86_64         5.18-5.el7               rhui-REGION-rhel-server-releases          66 k
 ntpdate                 x86_64         4.2.6p5-19.el7_0         rhui-REGION-rhel-server-releases          82 k

Transaction Summary
================================================================================================================
Install  1 Package (+2 Dependent packages)

Total download size: 689 k
Installed size: 1.6 M
Downloading packages:
(1/3): autogen-libopts-5.18-5.el7.x86_64.rpm                                             |  66 kB  00:00:00
(2/3): ntp-4.2.6p5-19.el7_0.x86_64.rpm                                                   | 540 kB  00:00:00
(3/3): ntpdate-4.2.6p5-19.el7_0.x86_64.rpm                                               |  82 kB  00:00:00
----------------------------------------------------------------------------------------------------------------
Total                                                                           1.3 MB/s | 689 kB  00:00:00
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
  Installing : ntpdate-4.2.6p5-19.el7_0.x86_64                                                              1/3
  Installing : autogen-libopts-5.18-5.el7.x86_64                                                            2/3
  Installing : ntp-4.2.6p5-19.el7_0.x86_64                                                                  3/3
  Verifying  : autogen-libopts-5.18-5.el7.x86_64                                                            1/3
  Verifying  : ntp-4.2.6p5-19.el7_0.x86_64                                                                  2/3
  Verifying  : ntpdate-4.2.6p5-19.el7_0.x86_64                                                              3/3

Installed:
  ntp.x86_64 0:4.2.6p5-19.el7_0

Dependency Installed:
  autogen-libopts.x86_64 0:5.18-5.el7                     ntpdate.x86_64 0:4.2.6p5-19.el7_0

Step 2: Configuration

Make changes in ntp.conf file

# vi /etc/ntp.conf

restrict 10.0.0.0 mask 255.255.255.0 nomodify notrap
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

Now start the ntpd service

# /etc/rc.d/init.d/ntpd start
Starting ntpd:            [ OK ]

Enable ntpd in multi-user levels.

# chkconfig ntpd on

To verify NTP peers synchronization status, delay, offset, jitter use the following command:

# ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*natasha.netwurx 209.242.224.11   2 u    -   64    1   67.464    6.336   0.038
 static-72-87-88 192.5.41.209     2 u    1   64    1   89.650   -3.463   0.000
 96.44.142.5     204.123.2.5      2 u    -   64    1   56.794    0.794   0.000
 ns.tx.primate.n .INIT.          16 u    -   64    0    0.000    0.000   0.000