chrony

• yum install chrony

[root@HHDDC-P-NTP ~]# sed '/^$/d;/^#/d' /etc/chrony.conf
server 0.cn.pool.ntp.org offline
server 1.cn.pool.ntp.org offline
server 2.cn.pool.ntp.org offline
server 3.cn.pool.ntp.org offline
driftfile /var/lib/chrony/drift
makestep 1.0 3
rtcsync
allow all
local stratum 10
logdir /var/log/chrony

# systemctl start chronyd
# systemctl enable chronyd


# firewall-cmd --zone=public --add-port=323/udp --permanent 
# firewall-cmd --reload