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I'm moving a program from a local server to a remote virtual private server. Our local server has a local IP address on our LAN of 10.x.y.z. Our router allows HTTP traffic to be forwarded to that computer on our network.

The new VPS that we are moving this program to is Windows Server 2008 R2 and it has 2 virtual NICs. One is connected and has a global IP address. The other is not connected to anything ("Network cable unplugged").

We have installed our program on the VPS and imported all our data from the old local installation. Our testing and subsequent search for the problem has revealed that the imported data will not work on this new server unless we can somehow find a way for this program to host itself on the same local IP address, 10.x.y.z.

Besides asking the datacenter to put a router between the Internet and this new VPS, is there anything I can do to host this program at 10.x.y.z? I've been looking into NAT - make the unused NIC 10.x.y.z and have the program host on that NIC (which would then communicate with the global NIC via NAT), but I'm not sure how to set it up. Is NAT the right solution? Is there a better solution? I'd rather this was all software based within the OS than asking for the router setup.

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What does that program do and why would that data be tied to a specific IP?? – squillman Feb 22 '11 at 18:04
up vote 0 down vote accepted

Add your private IP as a secondary IP address on your existing interface. And fix your code so it doesn't depend on having a specific fixed IP address.

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not our code - unfortunately. Its a 3rd party licensing product that we and our user base are tied to. Until this move, we had no idea that IP address was going to come into play. – user71738 Feb 22 '11 at 18:15
@user71738 Can you not contact the vender and ask to change the license for the new server? – squillman Feb 22 '11 at 18:18
That was one answer, a comma, and a sarky comment. Try adding your private IP as a secondary on your existing NIC. – mfinni Feb 22 '11 at 18:55
This easy answer seems to have been the fix we needed. I just went to the advanced properties for the global NIC IPv4 and added another IP address. Cool. Thanks for the pointer. – user71738 Feb 22 '11 at 23:29
That's the trick. Glad that worked. If you had needed it routed, you'd have to play with other things on the network, but it sounded like this is local-only. – mfinni Feb 22 '11 at 23:32

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