Check whether semanager is installed and execute the following command: rpm -qa | grep semanager.

If it is not already installed, execute the following command: yum-y install policy cores-python.

2 modify ssh configuration file

vi /etc/ssh/sshd_config

(1) Remove the comment of Port=22 first, and then change port 22 to the port you want to change.

3 modify SELinux

Semanageport-l | grepsh// Use the following command to view the currently allowed ssh ports in SElinux:

? (if there is no samanager command, yum installation: yum-y install policy cores-python)

4 add 20000 ports to? SELinux

semanage port-a-t ssh _ port _ t-p TCP？ 20000

semanage port -l | grep ssh？ //Then confirm whether to add.

If successful, the output will be:

ssh_port_t tcp 20000，22

5 restart the ssh service and execute the following command: service sshd restart or systemctl restart sshd.service

6. Add the firewall port number