Help with access to shell in Airlink MP70 to set up firewall

I have an Airlink MP70 and what I want to do is set up a more specific firewall than the web manager allows. Specifically, I want to filter outgoing traffic by source, and not by destination. I also want to be able to set up rules for ranges of addresses and not 1 by 1. Neither of these thing seem possible from the security tab of the manager (please correct me if I am wrong, or if i’m looking in the wrong place).

It seems to me that the easiest way to set something like this up would be to SSH into the modem and set rules directly, but I’ve had no luck SSHing into the device. I have SSH enabled in port 2332, but when I try to SSH, all I get is an “OK” after authentication, and then it gets stuck, and I can’t send any commands or do anything. The same happens with telnet. I’ve tried the “sconsole” user as suggested in other posts, but that didn’t work for me either.

Any advice on how to solve this problem would be appreciated!