1 基本原理描述

1.1 原理

在离线的局域网内，存在不少于2台服务器。

选择一台服务器作为时间基准,配置为NTP Server;

其他服务器向时间基准服务器同步，配置为NTP Client。

1.2 描述

2 配置方法

2.1 NTP Server配置方法

1) 首先，确保操作系统防火墙关闭。

通过执行sudo systemctl status firewalld命令查看；

若未关闭，则执行

sudo systemctl stop firewalld

sudo systemctl disable firewalld

进行防火墙关闭。

2) 检查chronyd服务是否安装和激活

通过执行sudo systemctl status chronyd命令查看；

若未安装和激活，则执行以下命令

安装命令： sudo yum install chronyd

激活命令： sudo systemclt start chronyd

sudo systemctl enable chronyd

3) 更改配置文件，配置为server模式

编辑文件/etc/chrony.conf

内容如下：

# Use public servers from the pool.ntp.org project.# Please consider joining the pool (http://www.pool.ntp.org/join.html).#pool pool.ntp.org iburstserver ntp.ntsc.ac.cn iburstserver ntp1.aliyun.com iburst#server cn.pool.ntp.org iburst# 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.注意下面是允许的网段allow 192.168.0.0/16# Serve time even if not synchronized to a time source.允许离线校时local stratum 10# 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# Specify directory for log files.logdir /var/log/chrony# Select which information is logged.#log measurements statistics tracking

4) 重新运行服务，自动加载更新的配置文件

sudo systemctl restart chronyd

5) 激活服务

运行命令： chronyc activity

应有类似如下返回

200 OK

0 sources online

0 sources offline

0 sources doing burst (return to online)

0 sources doing burst (return to offline)

2 sources with unknown address

6) 查看同步源

执行命令 chronyc sources

因为离线，返回如下

210 Number of sources = 0

MS Name/IP address Stratum Poll Reach LastRx Last sample

7) 查看同步情况

执行命令 chronyc tracking

返回如下：

Reference ID : 7F7F0101 ()

Stratum : 10

Ref time (UTC) : Sat Sep 13 03:05:36 2025

System time : 0.000000000 seconds fast of NTP time

Last offset : +0.000000000 seconds

RMS offset : 0.000000000 seconds

Frequency : 0.000 ppm slow

Residual freq : +0.000 ppm

Skew : 0.000 ppm

Root delay : 0.000000000 seconds

Root dispersion : 0.000000000 seconds

Update interval : 0.0 seconds

Leap status : Normal

2.2 NTP Client配置方法