Open the SSH config file:
sudo vim /etc/ssh/sshd_config
find the line with default port 22. In vim normal-mode (once you opened the vim, it is under normal-mode), find 22, and change it to the port that you want. Remember, don't use the common port, use the port number from 10000~60000.
After that, save the file. and restart the ssh service.
service ssh restart