Blocking a program's net access with ICS intact?

November 5, 2005 7:47 AM

Is there anything I can use to block a specific program's Internet access without screwing up Internet Connection Sharing in XP?

I've a program installed that intermittently attempts to access the Internet, for intrusive copy-protection purposes. I really, really want it to stop doing this. I'm using the basic Windows Firewall in XP, since I've got a second computer connecting through this one with Internet Connection Sharing, which apparently doesn't coexist happily with separate firewall software (I've tried Zonealarm Pro, which causes no end of trouble with the second PC loading Web pages). The program works fine when its 'net access is blocked with Zonealarm, and this stops the intermittent cd-key checking, albeit at the cost of reliable browsing on the second computer. Even with the program off its exceptions list, Windows Firewall seems incapable of blocking its access to the Internet. Does anyone know of any software (ideally free) that I can use to block this one program's access to my connection, without messing up ICS?

posted by terpsichoria to Computers & Internet (9 answers total)

Windows Firewall doesn't do what you want it to do because it isn't meant to do that. Its only purpose is to prevent intrusions, so it only blocks incoming access, not outgoing.

I have to think there's some way to configure Zonealarm so that it will block the offending program but not affect the ICS. Can't you set it so it allows all outgoing requests except those from specific software?

If not, I don't know of any free software that'll do what you want. I use Norton Internet Security, which does it very nicely, but it's not free.
posted by cerebus19 at 7:58 AM on November 5, 2005

a different firewall program to try is kerio. it will certainly do what you want and i believe it works with internet connection sharing.
posted by andrew cooke at 8:08 AM on November 5, 2005

You can indeed block a program's access with ZoneAlarm; I don't know how it plays with ICS, though.
posted by mookieproof at 8:21 AM on November 5, 2005

You are indeed going to need a better software firewall, at the very least. I have heard plenty of bad things about Zonealarm, however. You may want to try Sygate's personal firewall.
posted by Dipsomaniac at 11:03 AM on November 5, 2005

You could block the port it operates on through the router. Although, I think a firewall lke ZoneAlarm makes more sense.
posted by phr4gmonk3y at 11:35 AM on November 5, 2005

As the previous commenter said, one easy and pretty secure way to do this is to block the ports it's using at your router/nat. Here's a screenshot of what it looks like on my netgear router:


posted by Ethereal Bligh at 1:05 PM on November 5, 2005

that's only going to work if it's using some non-standard port. if i was writing software to check for licence abuse, i'd use port 80 (or 443). wouldn't you?
posted by andrew cooke at 1:31 PM on November 5, 2005

Easy. Add an entry to your hosts file, something along the lines of:

127.0.0.1 intrusive.copy-protection.com

It's pretty easy to figure out which site your program is connecting to. Just snag yourself a copy of TcpView from sysinternals.com.
posted by shinybeast at 4:01 PM on November 5, 2005

Or you could fix the application so it no longer tries to phone home. Check on bittorrent for a crack, er, update for the program. I've used cracks on almost every PC game I've ever owned (and legally purchased) to disable CD checks or other annoying behavior.

Possibly downside: It's in theory possible that the crack contains some sort of malware or would introduce a bug into the program.
posted by cactus at 5:31 PM on November 5, 2005