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I have multiple IP addresses configured to a NIC in Windows 2003/2008 Servers. This is done to get unique internal IPs to IIS websites, and there is a static NAT from each of these internal website addresses to corresponding public addresses. Each internal IP has a unique public IP.

Windows cmd and other applications use primary IP as a source IP by default.

But now I have a problem in that I would need to initiate HTTP/HTTPS requests from one of the secondary addresses to an external website that has allowed incoming traffic from only this secondary address.

Is it possible to assign source IPs to windows applications in a less intrusive way than setting the secondary IP as a primary IP in Windows, or switching public addresses in the NAT configuration? I don't want to hassle with NAT or IP settings in a production server with remote connections only.

What I'm looking for is an easier way to test this external url than developing and deploying a web application running on the site with this secondary IP assigned.

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up vote 2 down vote accepted

The short answer is no, unless the application specifically supports it. Otherwise it's up to the IP stack to determine how things get sent out so doing something like putting a weight on one interface is what you have to do.

A workaround for a browser would be to install a local proxy. WebScarab will allow you to do this, if you don't mind installing it on a server. You can set up a local proxy bound to a specific IP and then set your browser to use the local proxy. Thus the request will be sent to the remote server using the IP that the proxy is bound to.

If you use an internal proxy follow this guide to chain WebScarab to that proxy.

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You can't do it from the web browser, but you can add a default route for a particular IP/subnet that uses the secondary IP.

I know how to do this on Linux; no idea about windows, but I assume it will just be some call to "route add something"

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