Routing between subnets using Windows XP Pro

July 23, 2009 at 16:09:39
Specs: Windows XP Pro SP2
I'm looking to route data through an XP Pro machine with two network cards. A diagram of what I'm try to do can be seen here:

Someone else asked a similar question, but in two years, got no replys:

I think I need to make some route table edits. Just not sure which edits to make. Any suggestions would be appreciated.


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July 23, 2009 at 18:13:08
I've always considered dual homed windows machines a big pain in the butt & not worth the hassle, especially on a home network.

However, I'm glad you asked that question because I just learned something from the diagram that you posted. The caption showing the line ipenablerouter=1 is a registry change. I searched it on Google & there are a lot of hits. The registry key is:


(default is IPEnableRouter=0).

My guess that the registry change allows the NICs to communicate based on the routing tables you create using the route add command. I would have to actually try it to have a complete understanding of the procedure but it might be enough to get you started. Let me know how far you get.

How do you know when a politician is lying? His mouth is moving.

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July 23, 2009 at 18:56:06
I had already made that regedit, I only included the last part of the key for brevity.

The network is a model of one that exists in a plant. That pain you speak of would have me use different hardware could I.

My problem is that I don't know half what I should about routing. While waiting to see what others have to suggest I'm madly trying to teach myself to properly read a route table, a skill I wish I'd aquired sooner.

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July 23, 2009 at 19:57:10
Then the next step is understanding the route command. Looking at it, I see that you need to add routes for each NIC & the -p switch has to be used for windows to remember it after it reboots.

So far we have:
route -p add destination_IP netmask gateway metric

Let's say there are 2 NICs each on a different subnet, one is & the other is The way I understand it, if we were configuring we would use:
route -p add [metric] [if]

The metric is the number given to the NIC you are configuring which can be seen in the route print command.

[if] is the IP of the same interface. It's only used if you want to be sure that windows is using a particular interface.

That's my best guess. Change the command as you see fit & let me know what works.

How do you know when a politician is lying? His mouth is moving.

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Related Solutions

August 18, 2009 at 09:05:10
Well I came across your question while looking for an option to my own problem.
I came across the following link :

However, I you only want to restrict pc & to only sent emails, you might try (for the mean time) :
a. set all the computer in the same network (
b. use "Local Security Setting" (IPSec - I think) to only allow the pc to access only email server ip address.

I hope that can give some help

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