I know there isn't anything standard like Active Directory in the Linux world, but I'm assuming there's some way (or multiple ways) to implement a similar type of system. What options are out there? I've done some searching but so far I've just come up with stuff for integrating Linux into an Active Directory environment.
The primary need is single sign on and centralized account management. A Group Policy type setup would be useful too.
The reason I'm asking is because I'm doing research into what it would take to setup and maintain an all Linux environment for a new business. I'm trying to figure out the costs, downsides, and benefits of such an environment.