Here is some more information.  Maybe someone can help me on this?

The external sign-in mechanism is company wide.  Everyone uses it and it works great.  It functions like a web service, basically, user enters ID and password, after authentication, a string is returned and any application can then grab that string and do whatever it wants from that point.  Of course, if the authentication fails, the string will contain some error message.  All communication is done through https and part of what is returned is the authenticated user ID.  Password is never returned. 

What I need to for DNN to 1. receive the authenticated string, 2. parse it, 3. get the user ID, and 4.use that ID to log into DNN.  I can easily do 1 thru 3 by writing my own page in DNN but I have no idea how to do 4.

What I am willing to do is to create matching IDs in DNN and assign these IDs to groups in DNN for autherization.  But how do I trick DNN into allowing these IDs in?

I appreciate any suggestions,

Thanks,

Thanks a lot for your reply. 

Exactly what I was looking for. 

Based on what you told me, I was able to automatically log in a user by using the userController class!

I think instead of recreating users in DNN to match up the external authentication source, I will just automatically create the authenticated users in DNN when and if they try to log in to DNN.  Then leave the role assignment job to whoever is maintaining DNN. 

Thanks again for your insight!