Originally posted by powadha
I'm just wondering how hard it would be to build something like that with debian.
Extremely easy do a basic install forget about X or anything else being installed then put your firewall/router (iptables) script in the /etc/init.d directory and use update-rc.d to create the startup/shutdown links then run your script for the first time and you have a working setup. If you use woody as the install you will want to install a new kernel the packaging system does not know about it and it has several security problems so you will never be informed of the update/upgrade you should be doing with the new Sarge installer you get an up to date kernel and the packaging system knows about it so there are no problems there.
Edit: You may want to install ssh if you want to remotely administer the machine eg. run it without a keyboard/monitor attached.