I'm not sure that this is possible but I figure at worst, I'll be told you cannot do that.
Our organization has a report server that sits in a DMZ accessible by multiple units that have their own Active Directory Domains. There is no internet access to the DMZ (which is the only reason I'm even considering this solution as I realize that it is a big reduction in security). The server uses an authorization database to control what links and panels are visible and accessible to the viewer. No passwords are stored in the database, just Domain\Username combinations.
What we would like to happen is this. We want to rely on the fact that if the user had signed into their own system and had authenticated against their AD, then they are who they say they are. We would compare their user name against the authorization database and grant them access based on their roles.
We cannot use IIS Anonymous Authentication because we cannot access the viewer's logged on user name. Using any other Authentication doesn't work because the site then asks for user name and password which we cannot authenticate against multiple domains.
Essentially we want to short circuit Windows Authentication so that we automatically allow them to see the site but we can also retrieve the viewer's domain and user name.
I've looked at many SSO posts but all of them require the viewer to sign on once at the website level and/or deal with multiple sites across the domains. It seems to be a bit of overkill for this project to build out an SSO domain for one site that will only be accessed internally.