F5 Big-IP, X-Forwarded-For and IIS Logs

I published an ISAPI filter to work with our BIG-IP's and have just updated it with full x86 and x64 support. Check out the blog post I wrote on it a while ago. Just copy the enclosed F5XForwardedFor.dll to your server and reference it in the ISAPI section of your virtual site.

http://devcentral.f5.com/weblogs/joe/archive/2005/09/23/1492.aspx

This is discussed in this thread of the IIS Microsoft Community. It seems there is a helper to do that for IIS (Especifically stated to work with Microsoft ARR but it should work for any reverse proxy or load balancer).