Port Forwarding ssh using -R option

[Our Pal Al]

At least I think the -R option is what I want.

I've already got my home Mac listening to ssh on 22 as normal but moved it
behind a wireless router last night (doing ddns so I can still always reach
it from outside) and want to be able to ssh into my mac and my Xandros linux
box at will. I want to map port 22 on the router to the linux box and then
change the mac to listen to another port and I'll append that port # when I
ssh to it. 

Or maybe I'll do it the other way around once I figure out how to get ssh to
listen on another port. Once I've got the right syntax down I should be able
to change either but I can't get -R to work. Or is this even really the
option I want? How can I get ssh to listen on another port? Right now I hop
from the mac to the linux box but I'd like to eliminate a second step in
getting to either.

- opa