使用阿里云镜像站NTP服务搭建NTP服务器（基于CentOS 7系统）

参考链接：
阿里巴巴开源镜像站
NTP下载安装教程

一、NTP服务器介绍

网络时间协议（Network Time Protocol，NTP）服务器，也就是日常所说的NTP服务器，用来提供同步时间服务。在生产环境中，很多人都会忽略时间问题，实际上服务器、网络设备等，特别是Linux操作系统和虚拟化平台的时间不同步会导致很多问题。那么搭建一台NTP服务器就非常重要，生产环境中的设备可以直接与NTP服务器进行时间同步，NTP服务器本身也可以访问互连的NTP服务器进行同步。NTP服务器可以是物理服务器，也可以是虚拟机。

二、安装NTP服务组件

在Linux服务器（如，CentOS、Ubuntu等操作系统）上，使用命令进行安装。
本实验以CentOS 7 Linux环境进行演示操作记录。

YUM源已更新成阿里云开源镜像站里的CentOS镜像，加速快捷访问。

[root@ntp ~]# yum clean allLoaded plugins: fastestmirrorCleaning repos: base extras updatesCleaning up list of fastest mirrors[root@ntp ~]# yum repolistLoaded plugins: fastestmirrorDetermining fastest mirrors * base: mirrors.aliyun.com * extras: mirrors.aliyun.com * updates: mirrors.aliyun.combase                                                                                      | 3.6 kB  00:00:00     extras                                                                                    | 2.9 kB  00:00:00     updates                                                                                   | 2.9 kB  00:00:00     (1/4): base/7/x86_64/group_gz                                                             | 153 kB  00:00:00     (2/4): extras/7/x86_64/primary_db                                                         | 243 kB  00:00:00     (3/4): updates/7/x86_64/primary_db                                                        |  12 MB  00:00:01     (4/4): base/7/x86_64/primary_db                                                           | 6.1 MB  00:00:03     repo id                                   repo name                                                        statusbase/7/x86_64                             CentOS-7 - Base - mirrors.aliyun.com                             10,072extras/7/x86_64                           CentOS-7 - Extras - mirrors.aliyun.com                              500updates/7/x86_64                          CentOS-7 - Updates - mirrors.aliyun.com                           2,963repolist: 13,535[root@ntp ~]#

执行yum install -y ntp命令，进行ntp组件安装。

[root@ntp ~]# yum install -y ntpLoaded plugins: fastestmirrorLoading mirror speeds from cached hostfile * base: mirrors.aliyun.com * extras: mirrors.aliyun.com * updates: mirrors.aliyun.comResolving Dependencies--> Running transaction check---> Package ntp.x86_64 0:4.2.6p5-29.el7.centos.2 will be installed--> Processing Dependency: ntpdate = 4.2.6p5-29.el7.centos.2 for package: ntp-4.2.6p5-29.el7.centos.2.x86_64--> Processing Dependency: libopts.so.25()(64bit) for package: ntp-4.2.6p5-29.el7.centos.2.x86_64--> Running transaction check---> Package autogen-libopts.x86_64 0:5.18-5.el7 will be installed---> Package ntpdate.x86_64 0:4.2.6p5-29.el7.centos.2 will be installed--> Finished Dependency ResolutionDependencies Resolved================================================================================================================= Package                      Arch                Version                                Repository         Size=================================================================================================================Installing: ntp                          x86_64              4.2.6p5-29.el7.centos.2                base              549 kInstalling for dependencies: autogen-libopts              x86_64              5.18-5.el7                             base               66 k ntpdate                      x86_64              4.2.6p5-29.el7.centos.2                base               87 kTransaction Summary=================================================================================================================Install  1 Package (+2 Dependent packages)Total download size: 701 kInstalled size: 1.6 MDownloading packages:(1/3): autogen-libopts-5.18-5.el7.x86_64.rpm                                              |  66 kB  00:00:00     (2/3): ntpdate-4.2.6p5-29.el7.centos.2.x86_64.rpm                                         |  87 kB  00:00:00     (3/3): ntp-4.2.6p5-29.el7.centos.2.x86_64.rpm                                             | 549 kB  00:00:00     -----------------------------------------------------------------------------------------------------------------Total                                                                            1.7 MB/s | 701 kB  00:00:00     Running transaction checkRunning transaction testTransaction test succeededRunning transaction  Installing : autogen-libopts-5.18-5.el7.x86_64                                                             1/3   Installing : ntpdate-4.2.6p5-29.el7.centos.2.x86_64                                                        2/3   Installing : ntp-4.2.6p5-29.el7.centos.2.x86_64                                                            3/3   Verifying  : ntpdate-4.2.6p5-29.el7.centos.2.x86_64                                                        1/3   Verifying  : ntp-4.2.6p5-29.el7.centos.2.x86_64                                                            2/3   Verifying  : autogen-libopts-5.18-5.el7.x86_64                                                             3/3 Installed:  ntp.x86_64 0:4.2.6p5-29.el7.centos.2                                                                           Dependency Installed:  autogen-libopts.x86_64 0:5.18-5.el7                  ntpdate.x86_64 0:4.2.6p5-29.el7.centos.2                 Complete![root@ntp ~]#

三、配置阿里云镜像站NTP服务

配置之前，测试服务器是否能够访问到阿里云NTP服务器。

ping ntp.aliyun.com -c 5

修改/etc/ntp.conf配置文件。

注释掉原来配置文件中的NTP服务器地址，添加阿里云NTP服务器地址。

[root@ntp ~]# vi /etc/ntp.conf[root@ntp ~]# cat /etc/ntp.conf# For more information about this file, see the man pages# ntp.conf(5), ntp_acc(5), ntp_auth(5), ntp_clock(5), ntp_misc(5), ntp_mon(5).driftfile /var/lib/ntp/drift# Permit time synchronization with our time source, but do not# permit the source to query or modify the service on this system.restrict default nomodify notrap nopeer noquery# Permit all access over the loopback interface.  This could# be tightened as well, but to do so would effect some of# the administrative functions.restrict 127.0.0.1 restrict ::1# Hosts on local network are less restricted.#restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap# 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#broadcast 192.168.1.255 autokey    # broadcast server#broadcastclient            # broadcast client#broadcast 224.0.1.1 autokey        # multicast server#multicastclient 224.0.1.1        # multicast client#manycastserver 239.255.254.254        # manycast server#manycastclient 239.255.254.254 autokey # manycast client# Enable public key cryptography.#cryptoincludefile /etc/ntp/crypto/pw# Key file containing the keys and key identifiers used when operating# with symmetric key cryptography. keys /etc/ntp/keys# Specify the key identifiers which are trusted.#trustedkey 4 8 42# Specify the key identifier to use with the ntpdc utility.#requestkey 8# Specify the key identifier to use with the ntpq utility.#controlkey 8# Enable writing of statistics records.#statistics clockstats cryptostats loopstats peerstats# Disable the monitoring facility to prevent amplification attacks using ntpdc# monlist command when default restrict does not include the noquery flag. See# CVE-2013-5211 for more details.# Note: Monitoring will not be disabled with the limited restriction flag.disable monitor[root@ntp ~]#

四、启动NTP服务

启动ntp服务
systemctl start ntpd
设置ntp服务开机自启动
systemctl enable ntpd
查看ntp服务是否正常
systemctl status ntpd

[root@ntp ~]# systemctl start ntpd[root@ntp ~]# systemctl enable ntpdCreated symlink from /etc/systemd/system/multi-user.target.wants/ntpd.service to /usr/lib/systemd/system/ntpd.service.[root@ntp ~]# systemctl status ntpd● ntpd.service - Network Time Service   Loaded: loaded (/usr/lib/systemd/system/ntpd.service; enabled; vendor preset: disabled)   Active: active (running) since Sun 2021-11-28 19:06:34 CST; 23h left Main PID: 1988 (ntpd)   CGroup: /system.slice/ntpd.service           └─1988 /usr/sbin/ntpd -u ntp:ntp -gNov 28 19:06:34 ntp ntpd[1988]: Listen normally on 3 ens32 192.168.1.50 UDP 123Nov 28 19:06:34 ntp ntpd[1988]: Listen normally on 4 lo ::1 UDP 123Nov 28 19:06:34 ntp ntpd[1988]: Listen normally on 5 ens32 fe80::e4b:3ef:613c:8741 UDP 123Nov 28 19:06:34 ntp ntpd[1988]: Listening on routing socket on fd #22 for interface updatesNov 28 19:06:34 ntp ntpd[1988]: 0.0.0.0 c016 06 restartNov 28 19:06:34 ntp ntpd[1988]: 0.0.0.0 c012 02 freq_set kernel 0.000 PPMNov 28 19:06:34 ntp ntpd[1988]: 0.0.0.0 c011 01 freq_not_setNov 28 19:09:51 ntp ntpd[1988]: 0.0.0.0 c61c 0c clock_step -86398.982768 sNov 27 19:09:52 ntp ntpd[1988]: 0.0.0.0 c614 04 freq_modeNov 27 19:09:53 ntp ntpd[1988]: 0.0.0.0 c618 08 no_sys_peer[root@ntp ~]#

五、查看NTP源

ntpq -p

即[203.107.6.88]地址为阿里云NTP服务器的IP地址。

[root@ntp ~]# ntpq -p

remote           refid      st t when poll reach   delay   offset  jitter

203.107.6.88    100.107.25.114   2 u   56   64    7   13.685   -0.002   0.415

六、查看NTP服务状态

# 输出如下内容，表示在同步中，需要耐心等待一下[root@ntp ~]# ntpstatunsynchronised  time server re-starting   polling server every 8 s# 输出如下内容，表示同步成功[root@ntp ~]# ntpstatsynchronised to NTP server (203.107.6.88) at stratum 3   time correct to within 958 ms   polling server every 64 s

七、将客户端与NTP服务器同步

[root@client ~]# ntpdate -d 192.168.1.5028 Nov 19:37:54 ntpdate[2880]: ntpdate 4.2.6p5@1.2349-o Tue Jun 23 15:38:19 UTC 2020 (1)Looking for host 192.168.1.50 and service ntphost found : 192.168.1.50transmit(192.168.1.50)receive(192.168.1.50)transmit(192.168.1.50)receive(192.168.1.50)transmit(192.168.1.50)receive(192.168.1.50)transmit(192.168.1.50)receive(192.168.1.50)server 192.168.1.50, port 123stratum 3, precision -25, leap 00, trust 000refid [192.168.1.50], delay 0.02652, dispersion 0.00000transmitted 4, in filter 4reference time:    e54c9534.6f868aa9  Sat, Nov 27 2021 19:29:56.435originate timestamp: e54c9719.4617ce7f  Sat, Nov 27 2021 19:38:01.273transmit timestamp:  e54de898.b45bc870  Sun, Nov 28 2021 19:38:00.704filter delay:  0.02658  0.02655  0.02652  0.02660          0.00000  0.00000  0.00000  0.00000 filter offset: -86399.4 -86399.4 -86399.4 -86399.4         0.000000 0.000000 0.000000 0.000000delay 0.02652, dispersion 0.00000offset -86399.43147928 Nov 19:38:00 ntpdate[2880]: step time server 192.168.1.50 offset -86399.431479 sec[root@client ~]#

八、将系统时间同步到硬件

[root@client ~]# hwclock -w[root@client ~]# dateSun Nov 28 19:39:10 CST 2021