Have a look at this link, it shows may different standard connectors found on systems. This may help you find the one you are looking for. The link -->http://www.nullmodem.com/NullModem.htm
RJ-45 can be used for many things. Ethernet is only one of them. You can set it up as a direct connection with a cross-over ethernet cable. You can buy them at a good PC hardware store, or wire your own. They are wired differently to the ones that connect to a hub or router.
For ssh you need some kind of connection, a null modem can work if the system you want to connect from is in the same room, over a short distance.