Set up a time server

1、 Environmental requirements （ Both client and server should be installed chrony）

Two or more virtual machines are needed to act as servers and clients , All must have yum Source , Then install them separately ntp, Because I used it CentOS8, So the download command is ：yum install -y chrony
** Be careful ：** I am installing yum There are many problems with the source , I am persistent and use a way to install yum Source thus wasted a lot of time and failed to install , Later, I succeeded in borrowing the method of my classmates , Record the successful installation process here ：
a. First cd /etc/yum.repos.d/ Take a look at the configuration file ：

b. Delete these original yum Source ：rm -rf *

c. Check your own mirrored version , Go to relevant websites to download matching yum Source

The website here is ：https://developer.aliyun.com/mirror/?spm=a2c6h.25603864.0.0.50154ccaMggZGI, Just copy the corresponding command

d. install yum Source , The order is ：

curl -o /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-vault-8.5.2111.repo

If your mirror version is centos8, You can directly copy my commands

e. Test and install ntp（CentOS7 In the future, it will basically be chrony）, see yum Source installed successfully .

here yum The source is finally available

2、 Find a reliable time server address

This step is to search on Baidu , What I use here is ntp1.aliyun.com,
After you find the right address , Start with the virtual machine ping See if it can connect , It can be used if it can be connected .

3、 Edit the of the server chrony The configuration file

The order is ：vim chrony.conf
At this time, the first line of white text , It's a time server address he gave you , But we need to use our own virtual machine to test whether it can ping through , Can be used

My result is that Ping through , But it's slower , Because he is a foreign website .

Turn on chronyd service , Verification time