chronyd为隔离网络设置时间同步

参考链接：https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/configuring_basic_system_settings/using-chrony_configuring-basic-system-settings

1. 在选定为主节点的系统上，使用运行方式的文本编辑器进行如下编辑：root/etc/chrony.conf

   [root@controller1 ~]# vi /etc/chrony.conf
   
   driftfile /var/lib/chrony/drift
   commandkey 1
   keyfile /etc/chrony.keys
   initstepslew 10 controller1 controller2 controller3
   local stratum 8
   manual
   allow all

   其中 allow * 是允许客户端从中连接的网络或子网地址。

   controller1 controller2 controller3是时间同步的客户端节点，经实验，可以不用写入配置文件，一旦写入每重启一次服务都会有一个延迟，客户节点越多，延迟越大。猜测是给手动校准使用（manual）

2. 在选定为主服务器的直接客户端的系统上，使用运行方式的文本编辑器，按 如下方式编辑：root/etc/chrony.conf　　

server controller1
driftfile /var/lib/chrony/drift
logdir /var/log/chrony
log measurements statistics tracking
keyfile /etc/chrony.keys
commandkey 24
local stratum 10
initstepslew 20 controller1
allow 192.168.116.151

　　 3. 验证：chronyc sources

[root@controller3 ~]# chronyc sources
210 Number of sources = 1
MS Name/IP address         Stratum Poll Reach LastRx Last sample
===============================================================================
^* controller1                   8   6   377    33    -37us[  -48us] +/-  184us
[root@controller3 ~]# chronyc sources -v
210 Number of sources = 1

  .-- Source mode  '^' = server, '=' = peer, '#' = local clock.
 / .- Source state '*' = current synced, '+' = combined , '-' = not combined,
| /   '?' = unreachable, 'x' = time may be in error, '~' = time too variable.
||                                                 .- xxxx [ yyyy ] +/- zzzz
||      Reachability register (octal) -.           |  xxxx = adjusted offset,
||      Log2(Polling interval) --.      |          |  yyyy = measured offset,
||                                \     |          |  zzzz = estimated error.
||                                 |    |           \
MS Name/IP address         Stratum Poll Reach LastRx Last sample
===============================================================================
^* controller1                   8   6   377    45    -37us[  -48us] +/-  184us
[root@controller3 ~]# 

提示：如果未成功，请检查防火墙配置