A dumb terminal is the best bet; poke around and you're likely to score a perfectly usable box for free. If you want to emulate a dumb terminal on your Mac, the hitch is in hardware (USB to serial), not the softare--Terminal.app is excellent. Cisco also makes a web-based version of the Cisco Broadband Operating System (CBOS). All the software for this, including the web server, is already inside the router, but you'll need to get/purchase a username and password from Cisco. Additionally, you should be able to telnet (not SSH, to the best of my knowledge) in through the ethernet port as long as the two machines are connected with the appropriate cable and turned on. If you don't know the username and password for the router, you may need to blank it, i.e., restore all the default settings. CBOS, once you're in, is (1) really good, and (2), remarkably UNIX-like--you'll get the hang of it right away. Good luck!