I use multiple scripts, created by different companies, like Drupal and Vbulletin all on one domain. Can you share with me any ideas on how to make a universal login so that when someone creates an account on one script it works on the other (without them having to re-register)? It's kind of like Google's "Google Accounts," OpenID, and Facebook's "Facebook Connect" -- except it would be mine so no need to use any third party service. For example, one idea that I have found is to make a separate universal login script that all other scripts must access in order for any user to login. Any pro's and con's to this idea? Or do you have any other idea's that might be better than this idea? Thanks!
Janrain Engage is a good one and there is a plug-in for drupal for this as well as OpenID. Even if you created your own centralized authentication service you would need to manually modify all the login procedures on the scripts you have.
Check out Loginradius , a service enabling Social Login via 21 Openid and Oauth providers.And if you dont want their logo on the Login Interface you can opt for their Premium package for that.This service also provides Social Sharing via most popular Id providers like Facebook,Twitter and many more.
The easiest way is to learn how to write websites. Then you write whatever code is needed to ensure that all your scripts are accessing the same data, even if they use different databases. (Learn how a web app uses an AD login and you can apply the same techniques.) This isn't something that can be done unless you know how to read someone else's code, or at least decode their APIs.