chrony时钟源配置

#yum install chrony --RHEL7默认已安装chrony，而没有安装ntpd.

#systemctl status chronyd --查看chronyd服务状态
#systemctl enable chronyd --开机启动

#vi /etc/chrony.conf    --修改配置文件

#server 0.rhel.pool.ntp.org iburst   --注释这4行，由于是内网环境，所以无法跟外部时间服务器进行时间同步。
#server 1.rhel.pool.ntp.org iburst
#server 2.rhel.pool.ntp.org iburst
#server 3.rhel.pool.ntp.org iburst
  server 192.168.100.1 iburst    --添加这一行，表示与本机同步时间
 
local stratum 10    --该行取消注释

# Allow NTP client access from local network.
allow 192.168.100.0/24   --允许哪些服务器到这台服务器来同步时间

#systemctl restart chronyd --修改完配置文件后，重启chronyd服务

[root@rhel1 ~]# netstat -antulp | grep chronyd
udp        0      0 0.0.0.0:123             0.0.0.0:*                           705/chronyd         
udp        0      0 127.0.0.1:323           0.0.0.0:*                           705/chronyd         
udp6       0      0 ::1:323                 :::*                                705/chronyd     

timedatectl
# timedatectl status
# 两条命令效果等同

[root@rhel1 ~]# timedatectl 
       Local time: Sat 2017-10-07 10:55:22 CST
   Universal time: Sat 2017-10-07 02:55:22 UTC
         RTC time: Sat 2017-10-07 02:55:22
        Time zone: Asia/Shanghai (CST, +0800)
      NTP enabled: no
NTP synchronized: yes
  RTC in local TZ: no
       DST active: n/a

timedatectl set-time "YYYY-MM-DD HH:MM:SS"
timedatectl set-time "YYYY-MM-DD"
timedatectl set-time "HH:MM:SS"

timedatectl list-timezones
# 亚洲
timedatectl list-timezones |  grep  -E "Asia/S.*"

timedatectl set-timezone Asia/Shanghai

# 硬件时间默认为UTC
timedatectl set-local-rtc 1
# hwclock --systohc --localtime
# 两条命令效果等同

timedatectl set-ntp yes
# yes或no; 1或0也可以

[root@rhel1 ~]# chronyc sources
210 Number of sources = 1
MS Name/IP address         Stratum Poll Reach LastRx Last sample               
===============================================================================
^* rhel1.rusky.com              10   7   377   22m  -3603ns[  -19us] +/-   32us
[root@rhel1 ~]# 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               
===============================================================================
^* rhel1.rusky.com              10   7   377   22m  -3603ns[  -19us] +/-   32us
[root@rhel1 ~]#

[root@rhel2 ~]# vi /etc/chrony.conf 
# Use public servers from the pool.ntp.org project.
# Please consider joining the pool (http://www.pool.ntp.org/join.html).
#server 0.rhel.pool.ntp.org iburst  --注释这4行
#server 1.rhel.pool.ntp.org iburst
#server 2.rhel.pool.ntp.org iburst
#server 3.rhel.pool.ntp.org iburst
server 192.168.100.1 iburst    ---添加该行，表示到这台服务器去同步时间。

[root@rhel2 ~]# systemctl restart chronyd.service 
[root@rhel2 ~]# systemctl enable chronyd.service

[root@rhel2 ~]# timedatectl 
       Local time: Sat 2017-10-07 11:15:43 CST
   Universal time: Sat 2017-10-07 03:15:43 UTC
         RTC time: Sat 2017-10-07 03:02:26
        Time zone: Asia/Shanghai (CST, +0800)
      NTP enabled: no
NTP synchronized: yes   --为yes表示已同步
  RTC in local TZ: no
       DST active: n/a

#ntpdate 192.168.100.1   

[root@rhel1 ~]# date
Sun Oct  8 11:00:51 CST 2017
[root@rhel1 ~]# timedatectl
       Local time: Sat 2017-10-07 11:31:45 CST
   Universal time: Sat 2017-10-07 03:31:45 UTC
         RTC time: Sun 2017-10-08 03:01:57
        Time zone: Asia/Shanghai (CST, +0800)
      NTP enabled: no
NTP synchronized: no
  RTC in local TZ: no
       DST active: n/a

[root@rhel1 ~]# timedatectl set-ntp yes
[root@rhel1 ~]# timedatectl set-time "2017-10-08 11:00:50"
Failed to set time: Automatic time synchronization is enabled
[root@rhel1 ~]# timedatectl set-ntp no
[root@rhel1 ~]# timedatectl set-time "2017-10-08 11:00:50"
[root@rhel1 ~]# date
Sun Oct  8 11:00:51 CST 2017