It is recommended to change default SSH port (22) of Linux Server as part of security measure to harden your server. You can accomplish this by following below steps:
1) Login to the server via SSH as root:
ssh root@hostname/IP
where hostname/IP should be the host name / IP address to connect to the server.
2) We will need to edit sshd_config file and hence it is recommended that you backup original file before proceeding:
cp /etc/ssh/sshd_config /etc/ssh/sshd_config_backup
3) Open sshd_config in your favorite text editor (vim / nano):
vi /etc/ssh/sshd_config
-OR-
nano /etc/ssh/sshd_config
4) Navigate to line mentioning #Port (which is currently commended out with a # sign). Remove # and replace port 22 with your preferred new port # (eg 2220).
#Port 22 should be replaced with
Port 2220
5) Save your changes and close the sshd_config file
6) Important - If you have firewall running on the server, you will need to edit the rules and allow newly entered port # in firewall exception list.
7) Restart sshd service by running /etc/init.d/sshd restart
