By default only one port (port number 22) will be enabled as ssh/scp port in Linux
To enable multiple ssh ports we need to tweak /etc/ssh/sshd_config file.
Open /etc/ssh/sshd_config with any editor and search for line Port 22. Below this line add a new port which you want to use.
Example: I would like to use 12345 as another ssh port, add it as shown below.
Port 22 Port 12345
Save and exit from /etc/ssh/sshd_config file.
Restart sshd service with following command:
$ service sshd restart
After restarting sshd service test try to login/ssh with new port 12345, it should work.
You can also check list of ports opened for ssh using following command where you can see port 22 and 12345 in output:
$ netstat -anp | grep ssh
tcp 0 0 :::22 :::* LISTEN 3075/sshd tcp 0 0 :::12345 :::* LISTEN 3075/sshd