Linux 时钟同步服务关于服务端器和客户端的设置

冷不防 2023-09-25 18:16 53阅读 0赞

#### 时钟同步服务端和客户端的设置 ####

*   *  1、背景
     *  2、简介
     *  3、环境
     *  4、安装及配置
     *  5、配置使用
     *   *  案例测试背景：
         *  5.1、服务端的配置
         *  5.2、客户端的配置
         *  5.3、客户端查看同步源信息
     *  6、chrony 命令

### 1、背景 ###

多台服务器集中化部署完毕后服务器时间的快慢，久而久之肆意变换，有几台服务器就产生几个时间，对业务系统的数据的时效产生了一定的影响。

我们都知道时钟同步可以使用外网服务器，但是在内网内不能连接外网的时候也需要时钟同步，那怎么进行呢？

很多项目中会使用内网时间服务器作为时钟源，然后让其他机器都来同步这台机器即可。

针对linux系统下`ntp`服务和`chrony`服务都是作为服务器时钟同步服务，他们之间都可以互相进行同步。但是NTP与chrony不能同时存在，只能用其中一个。

因为在日常工作中主要操作的系统环境为 RHEL7 ，RHEL7中默认使用`chrony`作为时间服务器，也支持`NTP`，需要额外安装。所以本文就以`chrony`为重点进行展开介绍。

### 2、简介 ###

**Chrony**是一个开源的自由软件，是网络时间协议 NTP 的客户端和服务器软件。它能让计算机保持系统时钟与时钟服务器（`NTP`）同步，因此让你的计算机时间保持精确，`Chrony` 也可以作为服务端软件为其他计算机提供时间同步服务。

--------------------

Chrony由两个程序组成，分别是`chronyd`和`chronyc`。

*  `chronyd` 是一个后台运行的守护进程，用于调整内核中运行的系统时钟和时钟服务器同步。它确定计算机增减时间的比率，并对此进行补偿。
 *  `chronyc`提供了一个用户界面，用于监控性能并进行多样化的配置。它可以在`chronyd`实例控制的计算机上工作，也可以在一台不同的远程计算机上工作。

***NTP*** 是网络时间协议（`Network Time Protocol`）的简称，通过 `udp 123` 端口进行网络时钟同步。

### 3、环境 ###

<table> 
 <thead> 
  <tr> 
   <th>项目</th> 
   <th>版本</th> 
   <th>说明</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>CentOS</td> 
   <td>7.6.1810</td> 
   <td>操作系统版本</td> 
  </tr> 
 </tbody> 
</table>

### 4、安装及配置 ###

使用管理员账号操作

yum -y install chrony

systemctl start chronyd

systemctl enable chronyd

查看 `chrony.conf` 默认配置

cat /etc/chrony.conf

配置文件详解：

# 以server开，理论上想添加多少时间服务器都可以
    # 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
    
    # 根据实际时间计算出服务器增减时间的比率，然后记录到一个文件中，在系统重启后为系统做出最佳时间补偿调整
    # Record the rate at which the system clock gains/losses time.
    driftfile /var/lib/chrony/drift
    
    # 如果系统时钟的偏移量大于1秒，则允许系统时钟在前三次更新中步进
    # Allow the system clock to be stepped in the first three updates
    # if its offset is larger than 1 second.
    makestep 1.0 3
    
    # 启用实时时钟（RTC）的内核同步
    # Enable kernel synchronization of the real-time clock (RTC).
    rtcsync
    
    # 通过使用 hwtimestamp 指令启用硬件时间戳
    # Enable hardware timestamping on all interfaces that support it.
    #hwtimestamp *
    
    # Increase the minimum number of selectable sources required to adjust
    # the system clock.
    #minsources 2
    
    # 指定 NTP 客户端地址，以允许或拒绝连接到扮演时钟服务器的机器
    # Allow NTP client access from local network.
    #allow 192.168.0.0/16
    
    # Serve time even if not synchronized to a time source.
    #local stratum 10
    
    # 指定包含 NTP 身份验证密钥的文件
    # Specify file containing keys for NTP authentication.
    #keyfile /etc/chrony.keys
    
    # Get TAI-UTC offset and leap seconds from the system tz database.
    #leapsectz right/UTC
    
    # 指定日志文件的目录
    # Specify directory for log files.
    logdir /var/log/chrony
    
    # 选择日志文件要记录的信息
    # Select which information is logged.
    #log measurements statistics tracking

### 5、配置使用 ###

#### 案例测试背景： ####

*  服务端：192.168.100.200
 *  客户端：192.168.100.10

*首先一般默认都是已安装在Linux系统中的 若没有安装 则执行安装*

yum install chrony* -y

这里我们就以服务端和客户端的配置讲解做一个详细的步骤说明，其实很简单，只需要修改配置项即可。

#### 5.1、服务端的配置 ####

*  修改配置文件

vi /etc/chrony.conf

# Use public servers from the pool.ntp.org project.
    # Please consider joining the pool (https://www.pool.ntp.org/join.html).
    #pool 2.pool.ntp.org iburst        //注释此行
    server 192.168.100.200 iburst      //添加此行 server+服务端ip+iburst
     
    # Use NTP servers from DHCP.
    sourcedir /run/chrony-dhcp
     
    # Record the rate at which the system clock gains/losses time.
    driftfile /var/lib/chrony/drift
     
    # Allow the system clock to be stepped in the first three updates
    # if its offset is larger than 1 second.
    makestep 1.0 3
     
    # Enable kernel synchronization of the real-time clock (RTC).
    rtcsync
     
    # Enable hardware timestamping on all interfaces that support it.
    #hwtimestamp *
     
    # Increase the minimum number of selectable sources required to adjust
    # the system clock.
    #minsources 2
     
    # Allow NTP client access from local network.
    allow 192.168.100.0/24        //要设置允许的网络段
     
    # Serve time even if not synchronized to a time source.
    local stratum 10                //取消注释此行
     
    # Require authentication (nts or key option) for all NTP sources.
    #authselectmode require
     
    # Specify file containing keys for NTP authentication.
    keyfile /etc/chrony.keys
     
    # Save NTS keys and cookies.
    ntsdumpdir /var/lib/chrony
     
    # Insert/delete leap seconds by slewing instead of stepping.
    #leapsecmode slew
     
    # Get TAI-UTC offset and leap seconds from the system tz database.
    leapsectz right/UTC
     
    # Specify directory for log files.
    logdir /var/log/chrony
     
    # Select which information is logged.
    #log measurements statistics tracking

*  设置开机自启

systemctl enable chronyd

*  重启 chronyd 服务

systemctl restart chronyd

*  查看时间同步状态

timedatectl status

![在这里插入图片描述][090926424c554c8fbcab532c55e19c75.jpeg]

*  开启网络时间同步

timedatectl set-ntp true

*  如果有防火墙，则需要开放端口 udp 123

# 开启防火墙
    firewall-cmd --zone=public --add-port=123/udp --permanent
    #或者
    firewall-cmd --zone=public --add-service=ntp --permanent
    firewall-cmd --reload

#### 5.2、客户端的配置 ####

*  同样编辑文件

vim /etc/chrony.conf

*  修改如下配置项

# Use public servers from the pool.ntp.org project.
    # Please consider joining the pool (https://www.pool.ntp.org/join.html).
    #pool 2.pool.ntp.org iburst        //注释此行
    server 192.168.100.200 iburst      //添加此行 server+服务端ip+iburst
     
    # Use NTP servers from DHCP.
    sourcedir /run/chrony-dhcp
     
    # Record the rate at which the system clock gains/losses time.
    driftfile /var/lib/chrony/drift
     
    # Allow the system clock to be stepped in the first three updates
    # if its offset is larger than 1 second.
    makestep 1.0 3
     
    # Enable kernel synchronization of the real-time clock (RTC).
    rtcsync
     
    # Enable hardware timestamping on all interfaces that support it.
    #hwtimestamp *
     
    # Increase the minimum number of selectable sources required to adjust
    # the system clock.
    #minsources 2
     
    # Allow NTP client access from local network.
    #allow 192.168.0.0/16
     
    # Serve time even if not synchronized to a time source.
    #local stratum 10
     
    # Require authentication (nts or key option) for all NTP sources.
    #authselectmode require
     
    # Specify file containing keys for NTP authentication.
    keyfile /etc/chrony.keys
     
    # Save NTS keys and cookies.
    ntsdumpdir /var/lib/chrony
     
    # Insert/delete leap seconds by slewing instead of stepping.
    #leapsecmode slew
     
    # Get TAI-UTC offset and leap seconds from the system tz database.
    leapsectz right/UTC
     
    # Specify directory for log files.
    logdir /var/log/chrony
     
    # Select which information is logged.
    #log measurements statistics tracking

*  设置开机自启

systemctl enable chronyd

*  重启 chronyd 服务

systemctl restart chronyd

*  查看时间同步状态

timedatectl status

![在这里插入图片描述][ff0daa29c0c94cc5987c5b41b1175b39.png]  
如果 `NTP enabled` 这里是 no，则需要开启 NTP

timedatectl set-ntp true

#### 5.3、客户端查看同步源信息 ####

chronyc sources					#客户机查看同步源

可以看到如下输出

210 Number of sources = 1
    MS Name/IP address         Stratum Poll Reach LastRx Last sample               
    ===============================================================================
    ^* 10.0.244.1                    8   7   377    49    -17us[  -11us] +/-   12ms

到此，说明时钟服务器设置已经同步成功了，如果同步失败检查是否关闭了`selinux`和`firewalld`。

### 6、chrony 命令 ###

*  查看 ntp\_servers

chronyc sources -v

输出如下：

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               
    ===============================================================================
    ^* 10.0.244.1                    8   7   377    71    -29us[  -25us] +/-   12ms

*  查看 ntp\_servers 状态

chronyc sourcestats -v

输出如下：

210 Number of sources = 1
                                 .- Number of sample points in measurement set.
                                /    .- Number of residual runs with same sign.
                               |    /    .- Length of measurement set (time).
                               |   |    /      .- Est. clock freq error (ppm).
                               |   |   |      /           .- Est. error in freq.
                               |   |   |     |           /         .- Est. offset.
                               |   |   |     |          |          |   On the -.
                               |   |   |     |          |          |   samples. \
                               |   |   |     |          |          |             |
    Name/IP Address            NP  NR  Span  Frequency  Freq Skew  Offset  Std Dev
    ==============================================================================
    10.0.244.1                 12   7   23m     +0.004      0.087    +94ns    26us

*  查看 ntp\_servers 是否在线

chronyc activity -v

输出如下：

200 OK
    1 sources online
    0 sources offline
    0 sources doing burst (return to online)
    0 sources doing burst (return to offline)
    4 sources with unknown address

*  查看 ntp 详细信息

chronyc tracking -v

输出信息如下：

Reference ID    : 0A00F401 (10.0.244.1)
    Stratum         : 9
    Ref time (UTC)  : Wed Mar 22 12:36:46 2023
    System time     : 0.000011087 seconds fast of NTP time
    Last offset     : +0.000013647 seconds
    RMS offset      : 0.000166242 seconds
    Frequency       : 25.694 ppm fast
    Residual freq   : +0.003 ppm
    Skew            : 0.090 ppm
    Root delay      : 0.002177232 seconds
    Root dispersion : 0.011265529 seconds
    Update interval : 129.3 seconds
    Leap status     : Normal

[090926424c554c8fbcab532c55e19c75.jpeg]: https://img-blog.csdnimg.cn/090926424c554c8fbcab532c55e19c75.jpeg
[ff0daa29c0c94cc5987c5b41b1175b39.png]: https://img-blog.csdnimg.cn/ff0daa29c0c94cc5987c5b41b1175b39.png