How to create an IE8 add-on that adds an X-Forwarded-For header

I have several users coming from different places into a terminal server and browsing my site from the server. The problem is that i need to log what ip-address the user is actually coming from, not the ip for terminal server. I have full control over the terminal-server so I was thinking that some sort of add-on to IE8 on th开发者_StackOverflow社区e server could add an X-Forwarded-For-header.

1. Is this possible?
2. If so, this should be a common problem, does anything like this exists already?
3. If I need to make the add-on myself, where should I start?

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1. yes
2. never heard about anything that implements your requirements
3. you should a) find a way to get original user ip, maybe using terminal server api b) find a way how to create addon for browser your users are using c) glue those a) and b) together ;)