Question Bridging in Win10Pro, let traffic pass through software firewall

Nov 19, 2022
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I would like to add a secondary NIC to my Windows 10 Pro machine that functions as a server on a subnet, to let traffic from another subnet pass through the server software firewall. If I bridge the NIC, will the traffic pass through the firewall - or simply be routed from eth1 > eth0 > inet? If so, what would a good approach be to let the traffic go through the firewall?

Thanks for taking your time.

edit: software fw is Norton 360
 
Windows is not really designed to do this but you might be able to hack it to run as a router. Next almost all firewall stuff for windows assumes the source it the pc and it is sending to external ip addresses. Not sure your firewall software has the ability to filter traffic where both the input ip and the output IP are both external IP addresses. In addition even if you get this all to work if your goal is then to send the traffic to the internet the internet router would have to know how to send the traffic back through your pc to the other subnet.

You can not just bridge the ports. That would pretty much be the same as hooking both networks to a switch. Although you could run them overlapped like this they will not actually communicate. This is the function of a router.

In addition to all these problems if you use your pc as a router you now have to be very careful what you are doing on the pc. Running something that causes a spike in cpu usage will impact the network traffic passing through it.

Pretty much you would want to use a actual router to do this. Maybe you could load third party firmware on your router. You could also build a small router type of pc. If this is just something to play around with you can use a raspberry pi and add a second nic to it.
 

palladin9479

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You can do this, but I wouldn't recommand it. What you do is configure the second interface with a different IP range then your first interface, then configure the other computer to the IP address of that interface. On the main Windows computer you have to enable Internet Connection Sharing so that it'll properly do routing and NAPT.

https://answers.microsoft.com/en-us/windows/forum/all/internet-connection-sharing-in-windows-10/f6dcac4b-5203-4c98-8cf2-dcac86d98fb9

Is much easier to just buy a cheap SOHO router instead of trying to make Windows do something it's really designed to do.
 

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