1. Introduction to chrony

chrony is an open source software that follows the network time protocol ( ntp ), allowing the computer system time to be consistent with the time server time, chrony

It can also serve as a time server for other hosts.

ntp (network time protocol): port 123 of udp . Only one of chrony and ntp can exist in a computer.

2.chrony installation and configuration

2.1 chrony installation and configuration

VERY IMPORTANT: Before configuring, check that the firewall and selinux are turned off

yum install -y chrony
vim /etc/chrony.conf
[root@localhost ~]# cat /etc/chrony.conf
# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
server ntp.aliyun.com iburst （编写的网络时间服务器）
[root@localhost ~]# systemctl enable chronyd
[root@localhost ~]# systemctl enable chronyd
[root@localhost ~]# timedatectl status
Local time: Thu 2023-07-27 10:03:39 CST
Universal time: Thu 2023-07-27 02:03:39 UTC
RTC time: Thu 2023-07-27 02:03:39
Time zone: Asia/Shanghai (CST, +0800)
NTP enabled: yes （两个为yes即可）
NTP synchronized: yes
RTC in local TZ: no
DST active: n/a

3. Configure chrony as the time server of other hosts

3.1 Modify the chrony configuration file

在提供chrony时间服务器主机的chrony配置文件中修改以下地方
服务端
1.# Allow NTP client access from local network.
allow 192.168.27.0/24（开启指定ntp客户端）
2.# Serve time even if not synchronized to a time source.
local stratum 10
3.systemctl restart chronyd
客户端
1.下载安装chrony服务
2.编写chrony配置文件
vim /etc/chrony.conf
# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
server 192.168.27.120 iburst （ip是提供时间服务器的ip）
3.systemctl enable chronyd
systemctl start chronyd
检查是否同步成功
timedatectl status

4. chronyc command

View ntp services

Results view

^* : It means that the time synchronization is normal, and the synchronized time source is available

^- : represents an acceptable source

^? : The source of the time synchronization is unreachable

Check if ntp serveices is online

View ntp details

[root@localhost ~]# chronyc activity -v
200 OK

[root@localhost ~]# chronyc tracking -v

chrony-server