Set up enterprise NTP time server

One 、 brief introduction ：

NTP（NetworkTime Protocol, Network time protocol ） It's for Distributed Time The server Time synchronization with the client .NTP be based on UDP Message transmission , The use of UDP The port number is 123.

Use NTP The purpose of is to synchronize the clock of all devices with clock in the network , Keep the clocks of all devices in the network consistent , So that the device can provide a variety of applications based on a unified time .

For time errors The server Downtime , So run NTP Local system of , It can accept synchronization from other clock sources , It can also be used as a clock source to synchronize other clocks , And can synchronize with other devices .

Two 、 Build time server （ Server side ）

1. Set up the environment

Environmental Science ：CentOS6.4

Server192.168.126.1

Client192.168.126.2

2. install NTP yum –yinstall ntp

3. Modify the configuration file to add this line vim /etc/ntp.conf

restrict 192.168.126.0255.255.255.0 nomodify notrap

4. Find these two lines and remove the comments vi /etc/ntp.conf

#server127.127.1.0

#fudge127.127.1.0stratum 10

5. Start up the service

Chkconfig --level 345 ntpon

6. Start the service

/etc/init.d/ntpd start

7. The firewall needs to be turned on 123 Port or turn off the firewall

-A INPUT -m state --state NEW -m tcp -p tcp --dport 123 -jACCEPT

3、 ... and 、 client

1. Synchronize the time with the server and execute the following command

To perform manually or with crontab To execute

manual ：ntpdate 192.168.126.1

crontab –e

0 21 * * * ntpdate 192.168.126.1 >> /root/ntpdate.log 2>&1

2. View synchronization status ntpq –p

3. The firewall needs to be turned on 123 Port or turn off the firewall

-A INPUT -m state --state NEW -m tcp -p tcp --dport 123 -jACCEPT