Single Concurrent User Login - ASP.NET / Silverlight

I need to restrict users in my application to login from a one computer at a time (i.e. if they login from computer 2, computer 1 session will be ended). My application is cre开发者_如何学Goated in Silverlight and will be running in via an ASP.NET page inside IIS. This is an enterprise scale application so any solution has to be highly performant.

• I don't want to restrict the user to using a single computer.
• I can't rely on the IP address of the client to be unique.
• All server calls are made from the Silverlight application, so any solutions using SessionId needs to bear this in mind.

Are there any "standard" features available in Silverlight, ASP.NET or IIS that provide such a feature?

What other programming models can be used to acheive this?

Thanks, Mark

Session cookie ;) Simple. Basically if user logs into a new session, ask him to invalidate the old one (throw him out there), or close the new one (throw him out there).

OWA (Exchange 2010) has a mechanism like that.

Standard features: no. Needs programming.

Session Start event can be used to do the check.