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, feel free to navigate to the above URL.
What is Chrony client?
Chrony is a replacement of NTP client.
It can synchronize the system clock faster with better time accuracy and it is particularly useful for the systems which are not online all the time.
chronyd is smaller in size so 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 time stamping 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, 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 7Chrony 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, appended the same into all the client machines. Also, included 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 display 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 set 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
