I have several web servers in the LAN, addressable as http://serv1.lan/, http://serv2.lan/, etc.
To be addressed from outside the LAN, requests need to be passed through an authentication reverse proxy, such that https://proxy.com/serv1/ be translated into http://serv1.lan/ etc.
What are the regular expression rules needed to effect this conversion? The authentication server is IIS, but the proxy could also implemented in IsapiRewrite (which has a syntax similar to Apache).