网络时间服务和chrony
⽹络时间服务和chrony
实验练习：
- 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- 时间同步(centos6)
【例1】date命令查看系统时间[root@Magedu ~]# dateTue Jan 29 14:32:00 CST 2019【例2】查看硬件时钟[root@Magedu ~]# clockTue 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 ~]# dateTue 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- 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 ~]$dateMon Nov 11 22:02:55 CST 2019[root@centos6 ~]$date -s '-1 day'Sun Nov 10 22:03:10 CST 2019[root@centos6 ~]$ntpdate ntp.aliyun.com10 Nov 22:03:13 ntpdate[4232]: the NTP socket is in use, exiting[root@centos6 ~]$dateSun Nov 10 22:03:16 CST 2019[root@centos6 ~]$service ntpd stopShutting down ntpd: [ OK ][root@centos6 ~]$ntpdate ntp.aliyun.com11 Nov 22:04:06 ntpdate[4253]: step time server 203.107.6.88 offset 86399.986747 sec[root@centos6 ~]$dateMon Nov 11 22:04:08 CST 2019 ntp时间相差较⼤，是不能完成实时同步，那么可以⽤ntpdate命令来完成：(注意：如果按上述实验操作的话，切记关闭ntpd服务，在使用ntpdate同步时间，之前是为了查看同步状态才开启，这两个服务不可以同时启用。)【例6】根据上例，centos6开启了ntpd服务，也可当做时间服务器被它⼈使⽤[root@centos6 ~]$service ntpd startStarting ntpd: [ OK ][root@centos7 ~]#date -s '-1 day'Mon Nov 11 09:56:26 CST 2019[root@centos7 ~]#ntpdate 192.168.39.612 Nov 09:56:33 ntpdate[12472]: step time server 192.168.39.6 offset 86397.761731 sec[root@centos7 ~]#dateTue 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 192.168.39.612 Nov 10:01:37 ntpdate[12561]: the NTP socket is in use, exiting[root@centos7 ~]#dateMon 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 ~]#dateMon Nov 12 10:02:02 CST 2018（关闭ntpd同步时间）[root@centos7 ~]#systemctl stop ntpd[root@centos7 ~]#ntpdate 192.168.39.612 Nov 10:04:16 ntpdate[12603]: step time server 192.168.39.6 offset 31536000.031123 sec[root@centos7 ~]#dateTue 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 iburstserver 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 192.168.39.611 Nov 10:06:07 ntpdate[12644]: the NTP socket is in use, exiting[root@centos7 ~]#dateMon Nov 11 10:06:09 CST 2019[root@centos7 ~]#dateTue Nov 12 10:06:12 CST 2019You 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 iburstserver 1.centos.pool.ntp.org iburstserver 2.centos.pool.ntp.org iburstserver 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 192.168.39.611 Nov 10:26:00 ntpdate[13032]: the NTP socket is in use, exiting[root@centos7 ~]#dateMon Nov 11 10:26:02 CST 2019[root@centos7 ~]#dateMon Nov 11 10:26:03 CST 2019[root@centos7 ~]#dateMon Nov 11 10:26:05 CST 2019[root@centos7 ~]#daetbash: daet: command not found...Similar command is: 'date'[root@centos7 ~]#dateMon Nov 11 10:26:09 CST 2019[root@centos7 ~]#dateMon Nov 11 10:26:11 CST 2019[root@centos7 ~]#dateMon 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 192.168.39.612 Nov 10:30:39 ntpdate[13126]: step time server 192.168.39.6 offset 86400.017498 sec[root@centos7 ~]#dateTue 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 iburstserver 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。）- 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 iburstserver 172.16.0.1 iburstserver 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 ~]#dateTue 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 ~]#dateMon Nov 11 11:07:59 CST 2019[root@centos7 ~]#dateMon Nov 11 11:08:01 CST 2019[root@centos7 ~]#dateMon Nov 11 11:08:02 CST 2019[root@centos7 ~]#dateMon Nov 11 11:08:03 CST 2019[root@centos7 ~]#systemctl start chronyd[root@centos7 ~]#dateTue 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 iburstallow 192.168.37.0/24local 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.confecho server 172.16.0.1 iburst >> /etc/chrony.conf- 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 赞 (0)