login to multiple domains on same IIS server with same ASPNETDB members database?

basically I am building two websites (2 IIS sites) on the same win2k3 server that are utilizing a shared ASPNETDB members database. this was auto generated by visual studio w开发者_StackOverflow中文版hen integrating a login control, I'm sure you all know what it is.

The problem is that these 2 sites are working together and want a login on either site to server as a login for both sites.

so for example, user1 logs in (with asp.net login control) to domain.com, then navigates over to domain2.com - instead of requiring the user re-log-in on this domain, they should already be logged in (shared Profile.username parameter, same user from ASPNETDB)

I am a novice and have no idea where to begin with this or even how to best phrase the question (hence my inability to find help on google)

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Read about Single Sign On:

http://msdn.microsoft.com/en-us/library/ms972971.aspx

http://msdn.microsoft.com/en-us/library/dd577079.aspx

http://www.codeproject.com/KB/aspnet/SingleSignon.aspx