I need help changing settings (port forward?) after a physical server move

Question

Hi! I have a 10.6 server that I use at home. All is well and good there. The Airport Extreme assigns IP addresses for the network. I have www.mydomain.com that runs on the server -- I use it for testing web apps, etc. I use DynDNS with their client app that send the Comcast dynamic IP address back to DynDNS to keep the server on the grid.
My friend has a 10.6 server. He has www.hisdomain.com as a home business. He also uses DynDNS in a similar way. His landlord just informed him that his apartment is going to be sold from underneath him and he has to move ASAP. It looks like he won't have a permanent place for a month or two, so I offered to let him keep his server at my place.
We both run websites on port 443 and port 80.
After attaching his server to my network, his domain name updates, but typing www.hisdomain.com into a browser lands me on www.mydomain.com. I guess that the problem is port forwarding... the router sends all 443 and 80 requests to my server.
How do I configure this so that services for hisdomain.com are forwarded to his server while services for mydomain.com are forwarded to my server?

Answer 1

Short answer: you can't, although there are a couple of ways to sort-of kluge it.
Long answer: When your router gets an incoming connection, the only thing it has to go on is the IP address and port number (the domain name is sent much later, after TCP session with the server is established). So unless you have multiple public IP addresses (and a router that can handle them), or want to put the sites on different ports...
Speaking of which, here's kluge #1: run his server on different ports (e.g. 81 and 444, or maybe 8080 and 8043) and set the router to forward them to his server. Problem: the user has to include the port number in the URL when they connect, or they'll get your server.
Partial solution (and kluge #2): add a virtual site on your server, with the hostname www.hisdomain.com, go to its Aliases section, and add a rule in the URL Aliases & Redirects section, with these settings:
Type: RedirectMatch
Pattern: (.*)$
Path: http://www.hisdomain.com:81$1
Then build an SSL version that redirects to https://www.hisdomain.com:444$1. Problem: when the client connects, they'll get your SSL certificate instead of his (again, it happens before the client sends the domain name it's trying to reach), and get a cert error. No fix for this.
Kluge #3: instead of making the virtual site redirect clients to his server, add a reverse proxy so your server'll transparently forward requests to his server, and proxy the replies. I haven't done this, but I think what you need to do is make a virtual site (as above), and under its Proxy tab (the one under the virtual site, not the one under the Settings section), check the Enable Reverse Proxy box, leave the Proxy Path as "/" and the Sticky Session Identifier field blank, and add a Balancer member with the Server URL "http://hisinternalipaddress" and a blank Route. Or something like that. Again, you could do the same for https as well, but you'll have the same certificate problem.