How do I implement port redirecting/mapping on windows?

Question

I am programming a web proxy that is installed on client machines (same machine as the web browser).

I would like for all traffic that is web traffic to get redirected into my proxy server.

I am using a windows operating system (XP, Windows 2003, Windows 2008, Vista, Windows 7).

What would I need to do, to redirect all internet traffic on port 80 to my web proxy?

I noticed this software allows you to create port mappings in windows. And I can get my proxy to work in that way. One of the components they install is called NDIS and I assume they use that technology to be able to port redirect.

So my question is... what is the best (best as in easiest to implement) API or technology to use to program a port redirector in Windows?

Answer 1

Your options are Application Layer Proxy (= browser proxy settings), Layered Service Provider; TDI driver (or more modern equivalent?); NDIS driver. There is no simple answer to what is best or easiest. You need to take your own skill set into account, as well as the potential compatibility issues. Lots of other programs use each of these methods and you need to be compatible with them, or at least not break them.