Prevent Concurrent login of the same user in asp.net

Hello Team,

How do I prevent concurrent login of the same user from different browsers / tabs / devices ?

E.g. In my portal, say I have logged in with UserID - 123456 and password - 123.

Then, if same userid and password logs in on different tab or different browser, then system should give a message - user has already logged in.

Please guide. It is a but important and urgent.