ntp和chronyd

立即同步时间的坏处，影响某些计划任务执行

一、立即同步时间

方法一：

ntpdate ntp.aliyun.com

方法二：重启ntp服务

方法三：重启chrony服务

二、查看ntp和chrony状态

[root@textbox ~]# 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               
===============================================================================
^* localhost                     3   6    17     2    +62us[ +661us] +/-   88ms
[root@textbox ~]# 

[root@textbox ~]# ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*localhost       119.28.206.193   3 u   41   64  177    0.784    1.195 3656236

三、ntp做服务端的设置

#注释原来的ntp服务器，原来的ntp服务器都是centos.org美国的
[root@textbox ~]# sed   '/^server/s/^/#/' /etc/ntp.conf -i
#添加两个aliyun的
[root@textbox ~]# sed '1a server ntp.aliyun.com iburst'  /etc/ntp.conf -i
[root@textbox ~]# sed '1a server ntp1.aliyun.com iburst'  /etc/ntp.conf -i
#重启服务
[root@textbox ~]# systemctl restart ntpd
#ntp就这么简单，就可以当服务器使用了
[root@textbox ~]# ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
+120.25.115.20   10.137.53.7      2 u    4   64   17   42.560   -8.795   6.944
*203.107.6.88    100.107.25.114   2 u    4   64   17   15.542   -7.021   6.460
#123端口，udp
[root@textbox ~]# ss -lutnp | grep ntp
udp    UNCONN     0      0      192.168.38.140:123                   *:*                   users:(("ntpd",pid=61668,fd=19))
udp    UNCONN     0      0      127.0.0.1:123                   *:*                   users:(("ntpd",pid=61668,fd=18))
udp    UNCONN     0      0         *:123                   *:*                   users:(("ntpd",pid=61668,fd=16))
udp    UNCONN     0      0      fe80::69d0:5288:fda9:93ae%ens33:123                  :::*                   users:(("ntpd",pid=61668,fd=21))
udp    UNCONN     0      0       ::1:123                  :::*                   users:(("ntpd",pid=61668,fd=20))
udp    UNCONN     0      0        :::123                  :::*                   users:(("ntpd",pid=61668,fd=17))
#用另一台服务器测试
[root@linux5 ~]# ntpdate 192.168.38.140
 5 Sep 09:17:25 ntpdate[28423]: adjust time server 192.168.38.140 offset -0.007790 sec

四、chrony服务端配置

设置项比ntp多

[root@imooc-nginx ~]# sed '/^server/s/^/#/' /etc/chrony.conf -i
[root@imooc-nginx ~]# sed '1a server ntp.aliyun.com iburst' /etc/chrony.conf -i
[root@imooc-nginx ~]# sed '1a server 0.cn.pool.ntp.org iburst' /etc/chrony.conf -i
[root@imooc-nginx ~]# sed '1a server ntp1.aliyun.com iburst' /etc/chrony.conf -i
#即使当前时服务器未与指定ntp完成时间同步，照样提供服务
[root@imooc-nginx ~]# sed '1a local stratum 10' /etc/chrony.conf -i
#允许哪些服务器同步
[root@imooc-nginx ~]# sed '1a allow 192.168.0.0/16' /etc/chrony.conf -i
[root@imooc-nginx ~]# systemctl restart chronyd
[root@imooc-nginx ~]# systemctl enable chronyd
#查看chronyd状态
[root@imooc-nginx ~]# 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
||      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               
===============================================================================
^+ 120.25.115.20                 2   6    17     4   +766us[ +591us] +/-   21ms
^- 111.230.189.174               2   6    17     4    +98us[  +98us] +/-   49ms
^* 203.107.6.88                  2   6    17     4   -187us[ -361us] +/-   16ms
#测试
[root@textbox ~]# ntpdate 192.168.38.154
 5 Sep 09:33:25 ntpdate[61810]: adjust time server 192.168.38.154 offset -0.010546 sec

五、自动同步时间两种方式

1、ntpdate ntp.aliyun.com写入计划任务，每小时同步一次

2、所有服务器chrony都开启，其中一台做时间服务器，其他服务器的server都指向它

六、设置时区

[root@textbox ~]# timedatectl set-timezone Asia/Shanghai