Keith Roberts wrote: > So I guess I could configure my single NIC Centos 5.6 > machine connected to a 4 port ADSL router to act as the > external Gateway for other machine on the LAN side of the > router, possibly using NAPT on the Centos box? Yes, you can do that. You can also use it as a proxy server. When I said "firewall", I meant as firewall for the network, facing outside of the local network. There were people who would bring public (or semi-public, from ISP) IP to the switch and then hook up all PC's to that switch and use 2 subnets, one that ISP provided and one for the local LAN, all on the same switch, to save on hardware. That is not safe and not wise. Having firewall, as a software, running on the PC/server is good practice, sometimes even in the local environment, if you use it in the network that "external" people will hook up their PC's to and you have important data on it. Rare cases, but do exist. Better safe then sorry. Ljubomir