Modify SSH remote login port in Linux
SSH: short for Secure Shell, SSH (developed by SSH Communications Security Ltd.) is a secure protocol for remote logins. Using an SSH client, a user can connect to a server to transfer information in a more secure manner than other methods, such as telnet. The image to the right is an example of how an SSH session, which uses a command line interface, may look. SSH defaults to port 22.
Modify the SSH remote login port to 9999
The default iptables only open port 22 for ssh service, the use of additional ports such as 9999 need to add this port to a white list in iptables. If you don’t add this port, you will not connect to the SSH server.