I'm writing a web application that I want many portals to have access to. Basically I want to front this application with DNN so that the portal owners can configure their home page. But the core application lives outside DNN.

Most of my questions are hovering around authentication and authorization.  Can you easily pass credentials from DNN to an external application? Should I write a custom login module that uses my external application's profiles and roles?

It seems like DNN can do this but I can't seem to find information on just how to architect something like this.

Is this external application architecture the best approach or should I try to write my application as DNN modules or is there some other way?

Any direction, opinions, tutorials, links, etc would be helpful.