How To Install And Configure Chrony As NTP Client?

The NTP server and NTP client allow us to sync the clock across the network.

We had written an article about NTP server and NTP client installation and configuration in the past.

If you would like to check these, navigate to the above URL.

What Is Chrony Client?

Chrony is replacement of NTP client.

It can synchronize the system clock faster with better time accuracy and it can be particularly useful for the systems which are not online all the time.

chronyd is smaller, it uses less memory and it wakes up the CPU only when necessary, which is better for power saving.

It can perform well even when the network is congested for longer periods of time.

It supports hardware timestamping on Linux, which allows extremely accurate synchronization on local networks.

It offers following two services.

  • chronyc: Command line interface for chrony.
  • chronyd: Chrony daemon service.

How To Install And Configure Chrony In Linux?

Since the package is available in most of the distributions official repository. So, use the package manager to install it.

For Fedora system, use DNF Command to install chrony.

$ sudo dnf install chrony

For Debian/Ubuntu systems, use APT-GET Command or APT Command to install chrony.

$ sudo apt install chrony

For Arch Linux based systems, use Pacman Command to install chrony.

$ sudo pacman -S chrony

For RHEL/CentOS systems, use YUM Command to install chrony.

$ sudo yum install chrony

For openSUSE Leap system, use Zypper Command to install chrony.

$ sudo zypper install chrony

In this article, we are going to use the following setup to test this.

  • NTP Server: HostName: CentOS7.2daygeek.com, IP:192.168.1.5, OS:CentOS 7
  • Chrony Client: HostName: Ubuntu18.2daygeek.com, IP:192.168.1.3, OS:Ubuntu 18.04

Navigate to the following URL for NTP server installation and configuration in Linux.

I have installed and configured the NTP server on CentOS7.2daygeek.com so, append the same into all the client machines. Also, include the other required information on it.

The chrony.conf file will be placed in the different locations based on your distribution.

For RHEL based systems, it’s located at /etc/chrony.conf.

For Debian based systems, it’s located at /etc/chrony/chrony.conf.

# vi /etc/chrony/chrony.conf

server CentOS7.2daygeek.com prefer iburst
keyfile /etc/chrony/chrony.keys
driftfile /var/lib/chrony/chrony.drift
logdir /var/log/chrony
maxupdateskew 100.0
makestep 1 3
cmdallow 192.168.1.0/24

Bounce the Chrony service once you update the configuration.

For sysvinit systems. For RHEL based system we need to run chronyd instead of chrony.

# service chrony restart

# chkconfig chrony on

For systemctl systems. For RHEL based system we need to run chronyd instead of chrony.

# systemctl restart chrony

# systemctl enable chrony

Use the following commands like tacking, sources and sourcestats to check chrony synchronization details.

To check chrony tracking status.

# chronyc tracking
Reference ID    : C0A80105 (CentOS7.2daygeek.com)
Stratum         : 3
Ref time (UTC)  : Thu Mar 28 05:57:27 2019
System time     : 0.000002545 seconds slow of NTP time
Last offset     : +0.001194361 seconds
RMS offset      : 0.001194361 seconds
Frequency       : 1.650 ppm fast
Residual freq   : +184.101 ppm
Skew            : 2.962 ppm
Root delay      : 0.107966967 seconds
Root dispersion : 1.060455322 seconds
Update interval : 2.0 seconds
Leap status     : Normal

Run the sources command to displays information about the current time sources.

# chronyc sources
210 Number of sources = 1
MS Name/IP address         Stratum Poll Reach LastRx Last sample               
===============================================================================
^* CentOS7.2daygeek.com          2   6    17    62    +36us[+1230us] +/- 1111ms

The sourcestats command displays information about the drift rate and offset estimation process for each of the sources currently being examined by chronyd.

# chronyc sourcestats
210 Number of sources = 1
Name/IP Address            NP  NR  Span  Frequency  Freq Skew  Offset  Std Dev
==============================================================================
CentOS7.2daygeek.com        5   3    71    -97.314     78.754   -469us   441us

When chronyd is configured as an NTP client or peer, you can have the transmit and receive timestamping modes and the interleaved mode reported for each NTP source by the chronyc ntpdata command.

# chronyc ntpdata

Remote address  : 192.168.1.5 (C0A80105)
Remote port     : 123
Local address   : 192.168.1.3 (C0A80103)
Leap status     : Normal
Version         : 4
Mode            : Server
Stratum         : 2
Poll interval   : 6 (64 seconds)
Precision       : -23 (0.000000119 seconds)
Root delay      : 0.108994 seconds
Root dispersion : 0.076523 seconds
Reference ID    : 85F3EEF4 ()
Reference time  : Thu Mar 28 06:43:35 2019
Offset          : +0.000160221 seconds
Peer delay      : 0.000664478 seconds
Peer dispersion : 0.000000178 seconds
Response time   : 0.000243252 seconds
Jitter asymmetry: +0.00
NTP tests       : 111 111 1111
Interleaved     : No
Authenticated   : No
TX timestamping : Kernel
RX timestamping : Kernel
Total TX        : 46
Total RX        : 46
Total valid RX  : 46

Finally run the date command.

# date
Thu Mar 28 03:08:11 CDT 2019

To step the system clock immediately, bypassing any adjustments in progress by slewing, issue the following command as root (To adjust the system clock manually).

# chronyc makestep

Magesh Maruthamuthu

Love to play with all Linux distribution

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