One login for many codeigniter webapps?

Hi,

I have at least 6, 7 codeigniter 3.x web apps to handle my company operations. I would like to incorporate it as an ERP, so that user can have only one login and use required apps based on the permissions given.

Right now i have different login windows and sessions for different apps.

Any suggestions to do this?
is it possible to retain the session in multiple codeigniter apps?