网络时间服务和chrony

⽹络时间服务和chrony

实验练习:

  1. 准备实验环境:
    可用的centos6、7系统。  
    centos6 :192.168.37.6      
    centos7 :192.168.37.7
    关闭selinux
    关闭防火墙:cetos6 systemctl disable firewalld
               centos7 chkconfig iptables off
  1. 时间同步(centos6)
【例1】date命令查看系统时间
[root@Magedu ~]# date
Tue Jan 29 14:32:00 CST 2019

【例2】查看硬件时钟
[root@Magedu ~]# clock
Tue 29 Jan 2019 02:49:13 PM CST -0.334741 seconds

【例3】修改系统时间为2018年
[root@Magedu ~]# date -s '-1 year'
[root@Magedu ~]# date
Tue Jan 29 14:33:00 CST 2019

但此时硬件时间依然没修改,若要修改硬件时间则:
[root@Magedu ~]# clock -w
  1. ntp软件实现时间同步(centos6)
    centos6上默认安装了ntp软件包(包括客户端和服务器端),但是ntp同步需要⼀定时间才能完全同步时间的,⽽chrony同步时间⽐ntp快。centos7默认安装了chronyd服务。
【例4】在 centos6上查看ntp软件、修改配置⽂件  
[root@centos6 ~]$rpm -ql ntp
/etc/dhcp/dhclient.d
/etc/dhcp/dhclient.d/ntp.sh
/etc/ntp.conf
/etc/ntp/crypto
/etc/ntp/crypto/pw
/etc/rc.d/init.d/ntpd
/etc/sysconfig/ntpd
/usr/bin/ntpstat
/usr/sbin/ntp-keygen
/usr/sbin/ntpd
/usr/sbin/ntpdc
/usr/sbin/ntpq
/usr/sbin/ntptime
/usr/sbin/tickadj
(查看ntp包)

[root@centos6 ~]$vim /etc/ntp.conf 
#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
(以上都注释掉)
server ntp.aliyun.com iburst(这里加这一行作为同步时间服务器)

[root@centos6 ~]$service ntpd start   (启动ntpd服务)
Starting ntpd:                                             [  OK  ]

[root@centos6 ~]$chkconfig ntpd on    (开机启动)

[root@centos6 ~]$ss -nul   (监听了udp的123端口;)
State       Recv-Q Send-Q                                              Local Address:Port                                                Peer Address:Port 
UNCONN      0      0                                                               *:870                                                            *:*     
UNCONN      0      0                                                               *:111                                                            *:*     
UNCONN      0      0                                                               *:631                                                            *:*     
UNCONN      0      0                                                    192.168.39.6:123                                                            *:*     
UNCONN      0      0                                                       127.0.0.1:123                                                            *:*     
UNCONN      0      0                                                               *:123                                                            *:*     
UNCONN      0      0                                                       127.0.0.1:928                                                            *:*     
UNCONN      0      0                                                               *:34866                                                          *:*     
UNCONN      0      0                                                              :::46157                                                         :::*     
UNCONN      0      0                                                              :::870                                                           :::*     
UNCONN      0      0                                                              :::111                                                           :::*     
UNCONN      0      0                                        fe80::20c:29ff:fed0:823c:123                                                           :::*     
UNCONN      0      0                                                             ::1:123                                                           :::*     
UNCONN      0      0                                                              :::123                                                           :::*   

[root@centos6 ~]$ntpq -p   (查看同步状态)
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*203.107.6.88    100.107.25.114   2 u   62   64    7   14.783  -14.752   1.787   (前面为*时同步成功)

说明:ntp.aliyun.com 是时间服务器的ip地址;iburst是加速同步时间。如果时间相差较⼤,是不能完成实时同步的。
【例5】ntpdate命令,⽴即同步
[root@centos6 ~]$date
Mon Nov 11 22:02:55 CST 2019

[root@centos6 ~]$date -s '-1 day'
Sun Nov 10 22:03:10 CST 2019

[root@centos6 ~]$ntpdate ntp.aliyun.com
10 Nov 22:03:13 ntpdate[4232]: the NTP socket is in use, exiting

[root@centos6 ~]$date
Sun Nov 10 22:03:16 CST 2019

[root@centos6 ~]$service ntpd stop
Shutting down ntpd:                                        [  OK  ]

[root@centos6 ~]$ntpdate ntp.aliyun.com
11 Nov 22:04:06 ntpdate[4253]: step time server 203.107.6.88 offset 86399.986747 sec

[root@centos6 ~]$date
Mon Nov 11 22:04:08 CST 2019
  ntp时间相差较⼤,是不能完成实时同步,那么可以⽤ntpdate命令来完成:
(注意:如果按上述实验操作的话,切记关闭ntpd服务,在使用ntpdate同步时间,之前是为了查看同步状态才开启,这两个服务不可以同时启用。)
【例6】根据上例,centos6开启了ntpd服务,也可当做时间服务器被它⼈使⽤
[root@centos6 ~]$service ntpd start
Starting ntpd:                                             [  OK  ]
[root@centos7 ~]#date -s '-1 day'
Mon Nov 11 09:56:26 CST 2019
[root@centos7 ~]#ntpdate 192.168.39.6
12 Nov 09:56:33 ntpdate[12472]: step time server 192.168.39.6 offset 86397.761731 sec
[root@centos7 ~]#date
Tue Nov 12 09:56:35 CST 2019

(同上例使用ntpdate时不可以开启ntpd服务)
[root@centos7 ~]#date -s '-1 year'
Mon Nov 12 10:01:33 CST 2018
[root@centos7 ~]#systemctl start ntpd
[root@centos7 ~]#ntpdate 192.168.39.6
12 Nov 10:01:37 ntpdate[12561]: the NTP socket is in use, exiting
[root@centos7 ~]#date
Mon Nov 12 10:01:42 CST 2018
[root@centos7 ~]#date 
Mon Nov 12 10:01:44 CST 2018
[root@centos7 ~]#date 
Mon Nov 12 10:01:52 CST 2018
[root@centos7 ~]#date
Mon Nov 12 10:02:02 CST 2018

(关闭ntpd同步时间)
[root@centos7 ~]#systemctl stop ntpd
[root@centos7 ~]#ntpdate 192.168.39.6
12 Nov 10:04:16 ntpdate[12603]: step time server 192.168.39.6 offset 31536000.031123 sec
[root@centos7 ~]#date
Tue Nov 12 10:04:19 CST 2019

注意:(如果你的centos7配置了/etc/chrony.conf文件的上游服务器,时间会自动同步)
【例】更改centos7时间为一天以前,开启ntpd服务同步时间,同时实验chrony.conf配置文件设置上游服务器和不设置的区别。
[root@centos7 ~]#vim /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.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 ntp.aliyun.com iburst(开启服务并配置chrony.conf文件上游服务器)

(显示是ntpd正在使用无法同步但是之后会把时间自动同步回来)
[root@centos7 ~]#date -s '-1 day'
Mon Nov 11 10:05:40 CST 2019
[root@centos7 ~]#systemctl start ntpd
[root@centos7 ~]#ntpdate 192.168.39.6
11 Nov 10:06:07 ntpdate[12644]: the NTP socket is in use, exiting
[root@centos7 ~]#date
Mon Nov 11 10:06:09 CST 2019
[root@centos7 ~]#date
Tue Nov 12 10:06:12 CST 2019
You have new mail in /var/spool/mail/root

(注释掉配置的上游服务器)
[root@centos7 ~]#vim /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.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 ntp.aliyun.com iburst

(这里我做实验时发现注释掉chrony.conf文件的服务器还会自动同步,找到原因是ntp.conf文件还有时间服务器会自动同步所有都注释掉之后不会自动同步。)
[root@centos7 ~]#vim /etc/ntp.conf 
# 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

[root@centos7 ~]#date -s '-1 day'
Mon Nov 11 10:25:47 CST 2019
[root@centos7 ~]#systemctl start ntpd
[root@centos7 ~]#ntpdate 192.168.39.6
11 Nov 10:26:00 ntpdate[13032]: the NTP socket is in use, exiting
[root@centos7 ~]#date
Mon Nov 11 10:26:02 CST 2019
[root@centos7 ~]#date
Mon Nov 11 10:26:03 CST 2019
[root@centos7 ~]#date
Mon Nov 11 10:26:05 CST 2019
[root@centos7 ~]#daet
bash: daet: command not found...
Similar command is: 'date'
[root@centos7 ~]#date
Mon Nov 11 10:26:09 CST 2019
[root@centos7 ~]#date
Mon Nov 11 10:26:11 CST 2019
[root@centos7 ~]#date
Mon Nov 11 10:26:13 CST 2019

(这里关闭ntpd服务之后时间同步就可以用了,当然只是做实验做成这样的环境,正常可以自动同步时间,就不用调了,只是证明一下这个ntpd和ntpdate不可以同时使用。)
[root@centos7 ~]#systemctl stop ntpd
[root@centos7 ~]#ntpdate 192.168.39.6
12 Nov 10:30:39 ntpdate[13126]: step time server 192.168.39.6 offset 86400.017498 sec
[root@centos7 ~]#date
Tue Nov 12 10:30:42 CST 2019
【例7】ntp充当服务器(最好在centos6做这个实验,centos7的话要更改chrony的配置文件或者禁用服务。)
[root@centos6 ~]#vim /etc/ntp.conf
# 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 ntp.aliyun.com iburst     (以上都注释掉使用自己配置的时间服务器)
[root@centos6 ~]$service ntpd start (开启ntpd服务)
Starting ntpd:                                             [  OK  ]
[root@centos6 ~]$chkconfig ntpd on  (开机启动ntpd)
[root@centos6 ~]$ss -nul  (查看监听123端口)
State       Recv-Q Send-Q                                              Local Address:Port                                                Peer Address:Port 
UNCONN      0      0                                                               *:870                                                            *:*     
UNCONN      0      0                                                               *:111                                                            *:*     
UNCONN      0      0                                                               *:631                                                            *:*     
UNCONN      0      0                                                    192.168.39.6:123                                                            *:*     
UNCONN      0      0                                                       127.0.0.1:123                                                            *:*     
UNCONN      0      0                                                               *:123                                                            *:*     
UNCONN      0      0                                                       127.0.0.1:928                                                            *:*     
UNCONN      0      0                                                               *:34866                                                          *:*     
UNCONN      0      0                                                              :::46157                                                         :::*     
UNCONN      0      0                                                              :::870                                                           :::*     
UNCONN      0      0                                                              :::111                                                           :::*     
UNCONN      0      0                                        fe80::20c:29ff:fed0:823c:123                                                           :::*     
UNCONN      0      0                                                             ::1:123                                                           :::*     
UNCONN      0      0                                                              :::123                                                           :::*     

(这样就可以作为时间服务器使用了,但是只能在NAT内网环境使用。)
  1. 在centos7上chrony软件实现时间同步
    说明: /usr/bin/chronyc是客户端程序; /usr/sbin/chronyd是服务器端查询;
    /usr/lib/systemd/system/chronyd.service是服务控制⽂件。
【例8】配置chrony为客户端,配置3个时间服务器地址
[root@centos7 ~]#date -s '-1 day'
Mon Nov 11 11:07:57 CST 2019

[root@centos7 ~]#vim /etc/chrony.conf (添加三个时间服务器地址,把之前的注释掉。)
server ntp.aliyun.com iburst
server 172.16.0.1 iburst
server ntp1.aliyun.com iburst
[root@centos7 ~]#systemctl start chronyd   (开启服务)
[root@centos7 ~]#systemctl enable chronyd   (开机自启动)
Created symlink from /etc/systemd/system/multi-user.target.wants/chronyd.service to /usr/lib/systemd/system/chronyd.service.
[root@centos7 ~]#ss -nul (查看udp监听323端口)
State       Recv-Q Send-Q                                 Local Address:Port                                                Peer Address:Port              
UNCONN      0      0                                                  *:39900                                                          *:*                  
UNCONN      0      0                                      192.168.122.1:53                                                             *:*                  
UNCONN      0      0                                           *%virbr0:67                                                             *:*                  
UNCONN      0      0                                                  *:111                                                            *:*                  
UNCONN      0      0                                                  *:123                                                            *:*                  
UNCONN      0      0                                                  *:5353                                                           *:*                  
UNCONN      0      0                                                  *:34053                                                          *:*                  
UNCONN      0      0                                          127.0.0.1:323                                                            *:*                  
UNCONN      0      0                                                  *:929                                                            *:*                  
UNCONN      0      0                                          127.0.0.1:930                                                            *:*                  
UNCONN      0      0                                                 :::111                                                           :::*                  
UNCONN      0      0                                                ::1:323                                                           :::*                  
UNCONN      0      0                                                 :::37213                                                         :::*                  
UNCONN      0      0                                                 :::929                                                           :::*                  

[root@centos7 ~]#date
Tue Nov 12 11:07:40 CST 2019

(但是注意要是在启动服务之后在更改时间不会自动同步,需要重新启动服务立即同步时间。)
[root@centos7 ~]#date -s '-1 day'
Mon Nov 11 11:07:57 CST 2019
[root@centos7 ~]#date
Mon Nov 11 11:07:59 CST 2019
[root@centos7 ~]#date
Mon Nov 11 11:08:01 CST 2019
[root@centos7 ~]#date
Mon Nov 11 11:08:02 CST 2019
[root@centos7 ~]#date
Mon Nov 11 11:08:03 CST 2019
[root@centos7 ~]#systemctl start chronyd
[root@centos7 ~]#date
Tue Nov 12 11:07:40 CST 2019

【例9】chronyc客户端⼯具
[root@centos6 ~]# chronyc (进入交互式命令行)
chronyc> help (查看帮助子命令)
chronyc> sources -v (同步时钟)
chronyc> quit (退出)

[root@centos7 ~]#chronyc sources -v  (非交互式命令查看同步时钟)
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               
===============================================================================
^? 172.16.0.1                    0   8     0     -     +0ns[   +0ns] +/-    0ns
^* 203.107.6.88                  2   7   377    79  -1017us[-1218us] +/-   17ms
^+ 120.25.115.20                 2   7   377    78   -304us[ -304us] +/-   23ms

[root@centos7 ~]#systemctl status chronyd(查看开机是否启动)
[root@centos7 ~]#systemctl enable chronyd(设置开机自启动)
在centos6上安装chrony软件包:
[root@centos ~]# yum -y install chrony
[root@centos ~]# service ntpd stop

查看ntpd是否开机启动:
[root@centos ~]# chkconfig --list ntpd

把centos7当中时间服务器:
[root@centos ~]# vim /etc/chorny.conf
其中:
server 192.168.37.7 iburst

[root@centos ~]# service chornyd start
[root@centos ~]# chronyc sources -v
在centos7上配置,充当时间同步服务器:

[root@centos ~]# vim /etc/chrony.conf
其中:
server 172.16.0.1 iburst
allow 192.168.37.0/24
local stratum 10

[root@centos ~]# systemctl restart chronyd
说明:
 allow 192.168.37.0/24表示哪些主机可以向该主机同步时间;
 allow 0.0.0.0/0表示允许所有主机向该主机同步时间;
 local stratum 10表示当互联网不能访问时间服务器时,仍然使用本机时间提供时间服务。
再回到centos6,同步:

[root@centos ~]# chronyc sources -v 同步时间较慢。
显示:^* 192.168.37.7 即为成功。
总结:实现了使⽤⼀台主机向互联⽹上的时间服务器同步时间,在局域⽹内部,由其他主机向该主机同步时间即可。
在初始化脚本里,修改chrony配置文件。
sed 's/^server.*/#&/' /etc/chrony.conf
echo server 172.16.0.1 iburst >> /etc/chrony.conf
  1. timedatectl命令
【例10】列出所有时区
[root@centos ~]# timedatectl list-timezones
【例11】查看当前时区状态
[root@centos ~]# timedatectl status
【例12】修改时区
[root@centos ~]# timedatectl set-timezone Asia/Shanghai
[root@centos ~]# date
【例13】查看有效的配置⽂件
[root@centos ~]# grep -Ev "^(#.*|)$" /etc/chrony.conf
或:
[root@centos ~]# grep -Ev "^#|^$" /etc/chrony.conf

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