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RHEL7: NTP

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feichashao

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参考文档

http://www.ntp.org/rfc.html
http://linux.vbird.org/linux_server/0440ntp.php

查看日期时间及NTP概况

[root@rhel7-0 ~]# timedatectl
      Local time: Wed 2014-12-31 12:47:07 EST
  Universal time: Wed 2014-12-31 17:47:07 UTC
        RTC time: Sun 2015-01-04 08:51:13
        Timezone: America/New_York (EST, -0500)
     NTP enabled: n/a
NTP synchronized: no
 RTC in local TZ: no
      DST active: no
 Last DST change: DST ended at
                  Sun 2014-11-02 01:59:59 EDT
                  Sun 2014-11-02 01:00:00 EST
 Next DST change: DST begins (the clock jumps one hour forward) at
                  Sun 2015-03-08 01:59:59 EST
                  Sun 2015-03-08 03:00:00 EDT

查看和设置时区

[root@rhel7-0 ~]# timedatectl list-timezones
[root@rhel7-0 ~]# timedatectl set-timezone Asia/Hong_Kong

修改日期时间

格式”YYYY-MM-DD hh:mm:ss” 可以只改日期或者时间

[root@rhel7-0 ~]# timedatectl set-time "2015-01-04 16:55:00"

开启NTP服务

[root@rhel7-0 ~]# timedatectl set-ntp true

配置chrony

chrony提供NTP时间校正服务。

[root@rhel7-0 ~]# yum install chrony

配置文件在 /etc/chrony.conf
可以按如下方式配置NTP Server.

server 0.rhel.pool.ntp.org iburst
server 1.rhel.pool.ntp.org iburst
server 2.rhel.pool.ntp.org iburst
server 3.rhel.pool.ntp.org iburst

修改配置后重启chronyd服务

[root@rhel7-0 ~]# systemctl restart chronyd

可以用chronyc sources -v 查看同步时钟源。

[root@rhel7-0 ~]# chronyc sources -v
210 Number of sources = 3

  .-- 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
||                                                /   xxxx = adjusted offset,
||         Log2(Polling interval) -.             |    yyyy = measured offset,
||                                  \            |    zzzz = estimated error.
||                                   |           |                         
MS Name/IP address         Stratum Poll Reach LastRx Last sample
===============================================================================
^? dns.sjtu.edu.cn               0   6     0   10y     +0ns[   +0ns] +/-    0ns
^? gus.buptnet.edu.cn            0   6     0   10y     +0ns[   +0ns] +/-    0ns
^? dns1.synet.edu.cn             0   6     0   10y     +0ns[   +0ns] +/-    0ns

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