Can you prevent a user logging in multiple times with Janrain, or similar social network logins?

Question

I would like to enable logging in from multiple services on my site, but would not like users to login with, say, facebook and then logout and then back in with, say, Google+.

I am not sure if there is a practical way to detect that someone has done this?

I saw Janrain mentions account linking, is this provide this kind of service?

Security doesn't have to be watertight, but would like to make it hard to login multiple times and post from different accounts. At the same time, having multiple providers would be desirable to as not everyone uses Facebook.

Thanks for any help/info/suggestions.

Answer 1

Unfortunately there is no one point where you can check if a give account on one service is the same person as an account on another service.

One way is to drop a cookie on their browser when they log in with Service A, this cookie would indicate te service the user used to log in the last time. Then the next time they arrive on your site you can check for your cookie and then only show the login service they previously used.

Another option to make it more difficult to log in from multiple services is to request the email address of the user from the service and see if it already exists in your Database under a different account?