How to allow specific Facebook sign up ?

Hey everyone !

I have a wordpress website and I’d like people to be able to sign up using their Facebook account, and then login with it afterwards. Now that was the easy part, even though I can’t figure out how to make SFC work, but that’s my problem.

The real problem is : how to allow people to sign in ONLY if they are part of a specific network on Facebook ?

(Why do I want to do that ? Well, this website will be a community website for my campus, which will display “public” posts as well as “private” posts, and I want only the people from my school, the ones who have a valid email adress, finishing by @myschool.com, to be able to enter the private part of my website)

I hope I’ll get some answers,

Thank you very much ! ??