1、需要配置的计算机IP
192.168.0.131 bznode1
192.168.0.134 bznode2
192.168.0.135 bznode3
192.168.0.136 bznode4
设置IP=192.168.0.131为时钟服务器
IP=192.168.0.134服务器为需要同步机器
IP=192.168.0.135服务器为需要同步机器
IP=192.168.0.136服务器为需要同步机器
2、查看每个机器是否安装了ntp
[root@bznode1 ~]# rpm -qa | grep ntp
ntp-4.2.6p5-25.el7.centos.2.x86_64
ntpdate-4.2.6p5-25.el7.centos.2.x86_64
[root@bznode1 ~]#
这样的输出证明已经安装好了，其中包就是" ntp-4.2.6p5-25.el7.centos.2.x86_64"
如果已经安装则略过此步，如果没有安装则先安装ntp，安装ntp有两种方式
1.使用yum进行安装，并设置系统开机自动启动并启动服务
[root@ bznode1 ~]# yum -y install ntp
[root@ bznode1 ~]# systemctl enable ntpd
[root@ bznode1 ~]# systemctl start ntpd
2.离线安装
首先需要下载ntp的rpm包，把下载好的包放到/home文件夹下面
下载地址https://pkgs.org/
安装ntp可能会遇到下面的问题，缺少依赖
[root@ bznode1 home]# rpm -ivh ntp-4.2.6p5-25.el7.centos.2.x86_64
错误：依赖检测失败：
Libopts.so.25()(64bit) 被 ntp-4.2.6p5-22.el7.centos.x86_64 需要
ntpdate = 4.2.6p5-22.el7.centos 被 ntp-4.2.6p5-22.el7.centos.x86_64 需要
[root@ bznode1 home]#
上面给出的截图里面已经下载到了需要的rpm包，下面就依次进行安装即可
[root@bznode1 home]# rpm -ivh autogen-libopts-5.18-5.el7.x86_64.rpm
警告：autogen-libopts-5.18-5.el7.x86_64.rpm: 头V3 RSA/SHA256 Signature, 密钥 ID f4a80eb5: NOKEY
准备中... ################################# [100%]
正在升级/安装...
1:autogen-libopts-5.18-5.el7 ################################# [100%]
[root@bznode1 home]# rpm -ivh ntpdate-4.2.6p5-25.el7.centos.2.x86_64.rpm
警告：ntpdate-4.2.6p5-25.el7.centos.2.x86_64.rpm: 头V3 RSA/SHA256 Signature, 密钥 ID f4a80eb5: NOKEY
准备中... ################################# [100%]
正在升级/安装...
1:ntpdate-4.2.6p5-25.el7.centos.2 ################################# [100%]
[root@bznode1 home]# rpm -ivh ntp-4.2.6p5-25.el7.centos.2.x86_64.rpm
警告：ntp-4.2.6p5-25.el7.centos.2.x86_64.rpm: 头V3 RSA/SHA256 Signature, 密钥 ID f4a80eb5: NOKEY
准备中... ################################# [100%]
正在升级/安装...
1:ntp-4.2.6p5-25.el7.centos.2 ################################# [100%]
[root@bznode2 home]#
3、配置ntp.conf文件
配置NTP服务器的关键是需要配置这个文件
[root@ bznode1 ~]# vi /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
# 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 1.centos.pool.ntp.org iburst
#server 2.centos.pool.ntp.org iburst
#server 3.centos.pool.ntp.org iburst
#restrict 192.168.195.0 mask 255.255.0.0 nomodify
server 127.127.1.0
fudge 127.127.1.0 stratum 11
下面的省略了....
这是要改变的地方，server 0-3 注释掉， 加入本地时间服务器，主要是 127.127.1.0，由于是顶层服务，也就是说没有上级时间服务器 了，这里就是使用192.168.0.131的时间为准。接着，重启或者启动ntpd服务：
[root@ceph-node1 ~]# systemctl restart ntpd.service
此时，ntpd服务器已经配置好了。再执行：
[root@ceph-node1 ~]# systemctl enable ntpd.service
使服务在系统启动后就开启。
4、在客户端机器上进行配置
[root@ bznode2 ~]# vi /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
# 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 1.centos.pool.ntp.org iburst
#server 2.centos.pool.ntp.org iburst
#server 3.centos.pool.ntp.org iburst
#server 127.127.1.0 iburst local clock
#fudge 127.127.1.0 stratum 11
#restrict 192.168.195.0 mask 255.255.0.0 nomodify
server 192.168.0.131
fudge 127.127.1.0 stratum 11
下面省略....
主要是添加下面两行：
server 192.168.0.131
fudge 127.127.1.0 stratum 11
#这个是需要11，因为不是顶级的
配置好保存，重启ntp服务并设置跟随系统启动
[root@bznode2 home]# systemctl restart ntpd.service
[root@bznode2 home]# systemctl enable ntpd.service
Created symlink from /etc/systemd/system/multi-user.target.wants/ntpd.service to /usr/lib/systemd/system/ntpd.service.
查看ntp服务状态：
[root@bznode2 /]# ntpq -p
remote refid st t when poll reach delay offset jitter
=====================================================
*192.168.0.131 LOCAL(0) 6 u 66 64 377 0.094 -6.614 2.241
[root@bznode2 /]#
refid为LOCAL(0)为准确。
其他需要同步的服务器同样按照上面步骤进行操作即可
5、实时同步时间
执行命令 ntpdate 192.168.0.131可能会遇到下面的问题
[root@bznode2 home]# ntpdate 192.168.0.131
11 Jan 16:31:32 ntpdate[5723]: the NTP socket is in use, exiting
然后使用lsof –i:123命令
[root@bznode2 home]# lsof -i:123
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
ntpd 5670 ntp 16u IPv4 12173 0t0 UDP *:ntp
ntpd 5670 ntp 17u IPv6 12174 0t0 UDP *:ntp
ntpd 5670 ntp 18u IPv4 12179 0t0 UDP localhost:ntp
ntpd 5670 ntp 19u IPv4 12180 0t0 UDP bznode3:ntp
ntpd 5670 ntp 20u IPv6 12181 0t0 UDP bznode3:ntp
ntpd 5670 ntp 21u IPv6 12182 0t0 UDP localhost:ntp
[root@bznode2 home]# kill -9 5670
此后，再使用ntpdate 192.168.0.131就成功了！
[root@bznode2 home]# ntpdate 192.168.0.131
11 Jan 16:32:43 ntpdate[5753]: adjust time server 192.168.0.131 offset 0.150170 sec
[root@bznode2 home]#
如果lsof –i:123命令出现下面问题
[root@bznode2 /]# lsof -i:123
-bash: lsof: 未找到命令
[root@bznode2 /]#
则只需要安装上面截图中的lsof-4.87-4.el7.x86_64 (1).rpm就可以了
[root@bznode2 home]# rpm -ivh lsof-4.87-4.el7.x86_64\ \(1\).rpm
警告：lsof-4.87-4.el7.x86_64 (1).rpm: 头V3 RSA/SHA256 Signature, 密钥 ID f4a80eb5: NOKEY
准备中... ################################# [100%]
正在升级/安装...
1:lsof-4.87-4.el7 ################################# [100%]
[root@bznode2 home]#