Single Login for LAMP applications

I have the following LAMP application installations. Drupal Moodle OrangeHRM OpenDocMan * 2 installations Some work has been done but the functionality has not been achieved.? There is an admin section within Drupal created, there have been some code modifications within the other LAMP applications to work with the Admin functionality. I want two functionalities: Administrator: From within Drupal admin must be able to go in and select which users can get a single login to which LAMP app.? The admin must be able to grant and deny access as needed. User: User registers with Drupal first, then with the other LAMP applications.? Once they have registered, and the admin has setup the single login access, they will not need to login seperately in the future.? Once they login to Drupal, they can then access any applications that they have created the login for and that the Admin has given them access to.