redirect webusers based on groups

I want to have a webservice which authenticates the user via Kerberos (already know how to do that) and then redirect to 2 different services based on a group membership. The group can either be an active directory or local group in a config file or something.
I found several instructions to forward to the userfolder, but nothing like "forward users from group a to port 1234 an users from group b to port 2345" Any ideas how to solve this?

Best regards, Peter