Master Linux Time Sync with Chrony: Install, Configure, and Command Guide

Installation and Configuration

Install chrony, enable and start the daemon, then edit /etc/chrony.conf with the default settings shown.

yum -y install chrony
systemctl enable chronyd
systemctl start chronyd
vim /etc/chrony.conf

Default chrony.conf includes public pool servers, driftfile, makestep, rtcsync, and other common options.

# Use public servers from the pool.ntp.org project.
server 0.centos.pool.ntp.org iburst
server 1.centos.pool.ntp.org iburst
server 2.centos.pool.ntp.org iburst
server 3.centos.pool.ntp.org iburst

driftfile /var/lib/chrony/drift
makestep 1.0 3
rtcsync
#hwtimestamp *
#minsources 2
#allow 192.168.0.0/16
#local stratum 10
#keyfile /etc/chrony.keys
logdir /var/log/chrony
#log measurements statistics tracking

Usage

Server configuration

Modify chrony.conf to use internal NTP servers and allow the local network.

# Use public servers from the pool.ntp.org project.
server s1a.time.edu.cn iburst
server ntp.aliyun.com iburst
allow 192.168.8.0/24

Enable synchronization:

systemctl enable chronyd
systemctl restart chronyd
timedatectl status
timedatectl set-ntp true

Client configuration

Set the client to use a local NTP server and allow its address.

# Use public servers from the pool.ntp.org project.
server 192.168.8.5 iburst
allow 192.168.8.5

Enable synchronization (same commands as server).

systemctl enable chronyd
systemctl restart chronyd
timedatectl status
timedatectl set-ntp true

Commands

Common chronyc commands for monitoring:

# Show NTP sources
chronyc sources -v
# Show source statistics
chronyc sourcestats -v
# Show activity
chronyc activity -v
# Show tracking information
chronyc tracking -v

Timezone management with timedatectl:

timedatectl
timedatectl list-timezones
timedatectl set-timezone Asia/Shanghai
timedatectl set-time "2019-09-19 15:50:20"
timedatectl set-ntp true