Issue the following command:

sudo netstat -na|grep tcp

…which should show something like:

tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN
tcp        0      0 192.168.0.11:22         192.168.0.184:39662     ESTABLISHED
tcp6       0      0 :::22                   :::*                    LISTEN

The 0.0.0.0 in the first line indictes that SSH is listing on all ports.

The 2nd line can be ignored. This is simply the current connection.

Similarly, the ::: in the 3rd line indicates that SSH is listing on all ports with IPV6.