Internet connection sharing: firewall on both machines?

we have an internet connection sharing setup between 2 machines here, both running windows 2000. machine A is the one connected directly to the internet via a USB modem. machine B is connected to machine A via an ethernet cable. used to be machine B was a mac laptop and everything wroked fine. now though machine B is another PC running windows 2000 with comodo installed and neither firefox or internet explorer can access the internet, despite being enabled in the application monitor. if we switch off comodo on machine B everything’s fine, so that seems to be where the problem lies. should we even be running firewalls on both machines or would it be relative safe to just have it running on the host (machine A)?

Okay. I presume that ICS is working, without CFP installed (ie, before you installed CFP); you say that if you disable CFP it works fine. So we can extrapolate that everything’s fine on the Windows ICS end…

To address on CFP’s end, do the following:

On the CFP machine, go to (in CFP) Security/Tasks/Create a Zone. You will entire an IP range to encompass both computers. Give it a memorable name.

Then go to Security/Tasks/Define a New Trusted Network. Use the Zone you just created. This will add two rules to the Network Monitor, in positions Rule ID 0 & 1. The first will Allow IP Out from Any to Zone. The second will Allow IP In from Zone to Any. This will enable unimpeded communication/traffic between the two machines, thus allowing the internet connection to occur as normal. For good measure, reboot the client machine (this will clear out the memory cache and reset the new rules).

That should be all you need to do.

As far as the host machine goes - if it’s a Windows 32bit machine, then I recommend using CFP there as well. You will do the same thing with the Zone and Trusted Network.