I have been researching different linux firewall software and I am trying to find out if zeroshell can be ran with only one network card or does it require two? Being that the internet connection is less than 100mbit, I’m guessing that it should be able to be run with only one without a performance hit.
Zeroshell needs at least an ethernet interface to work. You can connect this interface to a switch to which you can attach a cable or xDSL modem to obtain the WAN connection and the hosts of your LAN.
But in any case, I think that a firewall with only one interface is not very secure.