Connecting to a specific port on an Airconsole.

I have a number of get console Airconsoles - these are nice, simple, small, and cheap terminal servers. 

Unfortunately(?) I don't use them often enough to always remember how to connect to a specific serial port -- what is the ssh port offset? 3000? 4000? What if I have a firewall that only allows port 22? 

This is my cheat-sheet:

Connecting to port 4:

ssh <ip> -p 4004

or

ssh <username>:4@<ip>

E.g:

ssh admin:4@192.0.2.1