XP - Firewalls - Cable Router

My friend ask me if a firewall can protect TWO computers simultaneously. He wants to monitor all ISP / Web traffic at the cable router IP port. Since both computers have a unique IP (shielded from the net) the cable router being the gate keeper with it's unique IP displayed to the net, I could not see a problem. This allows him to manage both computers (his and kids) with his XP and one firewall program installed on his computer. If yes, most popular firewalls can do this? Is there a downside? Thanks for any suggestions.

 

A router is a firewall. Why the need for a second software one?
If he want's monitoring software, get that, but it will only monitor the activity on the computer that it's installed on. There are some that will monitor LAN traffic, and monitor other systems on the LAN, but they're either very expensive (corporate use), or you need to have a server to run it on, with the clients access going through it.

 

Well, the home/small business broadband router/switch devices do contain a firewall. But it is a simple one with either open/close on ports and inbound monitoring only unless he got one of the really fancy ones like the SMC Barrier (which cost a bundle).

So as reboot mentioned, further protection would require software on each PC. The firewall that ships with XP isn't any fancier than the one with the router so if your friend wants to monitor outbound packets or set ports to only accept certain types of packets, he will need a different application.

A Google search for free firewall will give links to several good, no cost firewalls available for download.

 

Thank you very kindly for the fast answers. Friend now can make an informed decision.