1、服务器（ip:192.168.56.118）

安装ntp

# yum install ntp -y

编辑配置文件

[root@localhost ansible-k8s]# cat /etc/ntp.conf 
# For more information about this file, see the man pages
# ntp.conf(5), ntp_acc(5), ntp_auth(5), ntp_clock(5), ntp_misc(5), ntp_mon(5).

driftfile /var/lib/ntp/drift

# Permit time synchronization with our time source, but do not
# permit the source to query or modify the service on this system.
restrict default nomodify notrap nopeer noquery

# Permit all access over the loopback interface.  This could
# be tightened as well, but to do so would effect some of
# the administrative functions.
restrict 127.0.0.1 
restrict ::1

# Hosts on local network are less restricted.
#restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap        # 注释
restrict 192.168.56.0 mask 255.255.255.0 nomodify notrap        # 新增:添加可以同步时间的网段

# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
#server 0.centos.pool.ntp.org iburst        # server 0,1,2,3 注释掉网络服务器
#server 1.centos.pool.ntp.org iburst
#server 2.centos.pool.ntp.org iburst
#server 3.centos.pool.ntp.org iburst

#指明局域网中作为NTP服务器的IP
#service 192.168.56.118

server 127.127.1.0                      # 新增：外部时间服务器不可用时，以本地时间作为时间服务
fudge 127.127.1.0 stratum 10            # 新增

#broadcast 192.168.1.255 autokey        # broadcast server
#broadcastclient                        # broadcast client
#broadcast 224.0.1.1 autokey            # multicast server
#multicastclient 224.0.1.1              # multicast client
#manycastserver 239.255.254.254         # manycast server
#manycastclient 239.255.254.254 autokey # manycast client

# Enable public key cryptography.
#crypto

includefile /etc/ntp/crypto/pw

# Key file containing the keys and key identifiers used when operating
# with symmetric key cryptography. 
keys /etc/ntp/keys

# Specify the key identifiers which are trusted.
#trustedkey 4 8 42

# Specify the key identifier to use with the ntpdc utility.
#requestkey 8

# Specify the key identifier to use with the ntpq utility.
#controlkey 8

# Enable writing of statistics records.
#statistics clockstats cryptostats loopstats peerstats

# Disable the monitoring facility to prevent amplification attacks using ntpdc
# monlist command when default restrict does not include the noquery flag. See
# CVE-2013-5211 for more details.
# Note: Monitoring will not be disabled with the limited restriction flag.
disable monitor

修改/etc/sysconfig/ntpd 文件

# vim /etc/sysconfig/ntpd
// 增加内容如下（让硬件时间与系统时间一起同步）
SYNC_HWCLOCK=yes

启动服务

# systemctl start ntpd

查看服务

[root@localhost ansible-k8s]# netstat -anput | grep ntpd
udp        0      0 172.18.0.1:123          0.0.0.0:*                           20525/ntpd          
udp        0      0 172.17.0.1:123          0.0.0.0:*                           20525/ntpd          
udp        0      0 192.168.56.118:123      0.0.0.0:*                           20525/ntpd          
udp        0      0 10.4.7.132:123          0.0.0.0:*                           20525/ntpd          
udp        0      0 127.0.0.1:123           0.0.0.0:*                           20525/ntpd          
udp        0      0 0.0.0.0:123             0.0.0.0:*                           20525/ntpd

2、客户端(IP: 192.168.56.11)

安装ntpdate

# yum install ntpdate -y

测试

# ntpdate 192.168.56.118
15 Jun 15:35:12 ntpdate[16461]: step time server 192.168.56.118 offset 0.710982 sec

3、注意事项

• 对于centos7系统有默认的时间服务chronyd，他会默认开机自启，系统就会略过ntpd的开机自启，就会出现ntpd虽然加入开机自启，但是服务并未启动，此时关闭chronyd的开机自启即可

• 如果出现端口不通的情况，需要关闭防火墙