### Install Chrony.
[root@testos ~]# yum -y install chrony
### Edit/Update Chrony Configuration file
[root@testos ~]# vi /etc/chrony.conf
### line 3: change servers for synchronization
#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 server <NTP1 SERVER ADDRESS> iburst server <NTP2 SERVER ADDRESS> iburst server <NTP3 SERVER ADDRESS> iburst
### line 25: add the network range you allow to receive requests
allow 10.0.0.0/24
### Start&Enable Chrony service
[root@testos ~]# systemctl start chronyd
[root@testos ~]# systemctl enable chronyd
### If Firewalld is running, allow NTP service. NTP uses 123/UDP.
[root@testos ~]# firewall-cmd –add-service=ntp –permanent
success
[root@testos ~]# firewall-cmd –reload
success
### Verify it works normally like follows.
[root@testos ~]# chronyc sources 170 Number of sources = 3 MS Name/IP address Stratum Poll Reach LastRx Last sample =============================================================================== ^+ ntp1.ntp.unixtest.com 2 6 17 8 -1028us[-1261us] +/- 14ms ^* ntp2.ntp.unixtest.com 2 6 17 8 -1241us[-1474us] +/- 15ms ^? ntp3.ntp.unixtest.com 0 6 0 10y +0ns[ +0ns] +/- 0ns