Integrated security and form based login

[HG]

Hi group.

I am in the middle of defining the overall system architecture for a new
project, and I am facing some security issues. It is an intranet web
application accessed through web clients (ASP.NET)

This is what I want:
Use integrated security, which will automatically login the user to the web
app, if the user is logged in on the client.
In case the user is not logged in or the web app is accessed from a remote
client security should fall back to form based security, requesting a login.

Is it possible...and how do I do it?

Thanx in advance..

Best regards

Henrik