A server will use the Network Time Protocol (NTP) to synchronize its time with internet standard reference clocks via a hierarchy of NTP servers. The two common NTP daemon server implementations are ntpd and chronyd. Chrony is known to be much faster in time synchronization in comparison to the traditional NTP. Chrony can also handle intermittent network connections and bandwidth saturation.
The Chrony RPM package is available from the standard Amazon Linux 2 repositories. You can quickly install the package by running the following commands:
sudo yum -y install chronydThere is a daemon for Chrony called chronyd, which runs in the background to monitor system time and status of the time server specified in the chrony.conf file.
Configure Chrony NTP Server on Amazon Linux 2
The server configuration file is /etc/chrony.conf. Edit this file to set NTP Servers where time synchronization reference will happen.
sudo vim /etc/chrony.confSet the NTP servers to synchronize. Please replace the values here with your own timezone NTP servers.
pool 0.africa.pool.ntp.org iburst
pool 1.africa.pool.ntp.org iburst
pool 2.africa.pool.ntp.org iburstUse public servers from the pool.ntp.org project. You can get all zonal Pool Servers.
Once the file is updated with servers to reference for time updates, restart chronyd service.
sudo systemctl restart chronyd
sudo systemctl enable chronydCheck service status:
$ systemctl status chronyd
● chronyd.service - NTP client/server
Loaded: loaded (/usr/lib/systemd/system/chronyd.service; enabled; vendor preset: enabled)
Active: active (running) since Mon 2025-02-03 05:17:16 UTC; 23s ago
Docs: man:chronyd(8)
man:chrony.conf(5)
Main PID: 29890 (chronyd)
CGroup: /system.slice/chronyd.service
└─29890 /usr/sbin/chronyd
Feb 03 05:17:16 ip-172-31-39-10.eu-west-1.compute.internal systemd[1]: Starting NTP client/server...
Feb 03 05:17:16 ip-172-31-39-10.eu-west-1.compute.internal chronyd[29890]: chronyd version 3.2 starting (+CMDMON +NTP +REFCLOCK +RTC +PRIVDROP +SCFILTER ...DEBUG)
Feb 03 05:17:16 ip-172-31-39-10.eu-west-1.compute.internal chronyd[29890]: Frequency 13.093 +/- 0.052 ppm read from /var/lib/chrony/drift
Feb 03 05:17:16 ip-172-31-39-10.eu-west-1.compute.internal systemd[1]: Started NTP client/server.
Feb 03 05:17:25 ip-172-31-39-10.eu-west-1.compute.internal chronyd[29890]: Selected source 156.38.0.155If you have a running firewalld service and the server will serve as NTP Server to other clients, you may have to allow in the firewall.
sudo firewall-cmd --add-service=ntp --permanent
sudo firewall-cmd --reloadIf you prefer allowing from specific subnet.
sudo firewall-cmd --remove-service=ntp --permanent
sudo firewall-cmd --add-rich-rule 'rule family="ipv4" service name="ssh" source address="172.31.0.0/16" accept' --permanent
sudo firewall-cmd --reloadWhere 172.31.0.0/16 is the source address where NTP protocol is allowed for incoming traffic.
$ firewall-cmd --list-rich-rules
rule family="ipv4" source address="172.31.0.0/16" service name="ssh" acceptVerify Chrony is working by pulling correct time.
$ sudo chronyc sources
210 Number of sources = 12
MS Name/IP address Stratum Poll Reach LastRx Last sample
===============================================================================
^+ ntp1.inx.net.za 2 6 377 64 +1643us[+1379us] +/- 119ms
^+ mail.saasta.ac.za 2 6 377 64 +3552us[+3288us] +/- 112ms
^+ cpt-ntp.mweb.co.za 2 6 377 65 +665us[ +401us] +/- 195ms
^+ 156.38.0.219 2 6 375 1 +1074us[+1074us] +/- 126ms
^+ ntp.cd.net.za 2 6 377 64 +827us[ +827us] +/- 134ms
^+ ntp1.za.hypr.digital 2 6 377 1 +2071us[+2071us] +/- 129ms
^+ ntp3.inx.net.za 2 6 377 4 +3273us[+3273us] +/- 121ms
^+ ntp.dts.mg 2 6 377 64 +706us[ +706us] +/- 148ms
^- repository.habari.co.tz 2 6 377 66 +24ms[ +24ms] +/- 277ms
^- ns2.botsnet.bw 2 6 377 1 +7376us[+7557us] +/- 267ms
^* 196.200.160.123 2 6 377 1 -3843us[-3661us] +/- 96ms
^+ apollo.slash.tech 2 6 377 68 -2247us[-2321us] +/- 94msChrony Client Configurations
On your client machines install chrony package:
sudo yum -y install chronyModify configuration file and add your NTP Server.
$ sudo vim /etc/chrony.conf
pool 172.31.20.11 iburstSet your machine timezone:
sudo timedatectl set-timezone Africa/NairobiStart and enable Chronyd Service.
sudo systemctl enable --now chronydTest with the command below.
sudo chronyc sourcesCheck your system date to confirm if it is correct:
$ date
Mon Feb 03 08:34:54 EAT 2025More articles on Amazon Linux:
