Vi /etc/ssh/sshd_config, find port 22, then change port 22 to the port number you want, restart SSH service: /etc/init.d/sshd, and then test SSH connection: ssh localhost -p Your port number, the connection is successful. \x0d\ If you can't use ssh connection to be on the safe side, because one port can't be connected (for example, it is attacked), you can use multiple ssh connection ports, or modify it in the configuration file /etc/ssh/sshd_config, and run vi /etc/ssh/sshd_config to find the port number. Then add a line below: Port 23, thus adding a new connection port, restarting SSH service, \x0d\ testing ssh localhost -p 23, and the connection is successful. \x0d\ In addition, it should be noted that if there is no problem in the local test, but it is still impossible to use the third room tool for external SSH, you need to close the firewall \x0d\ and restart SSHD. That's good.