How to manage users and access to the different sites in intranet from a main server?

[zjrzovajz]

I have more than four sites on my intranet. Now what i want to do is to manage all these sites from the main site. I need to manage that main site which can give access to the users to go to these sites and do the thing that can be done by logging to the individual sites.I read about OpenID on this link http://devzone.zend.com/article/3581Now I want to know that if I can manage this using OpenID or is there any other way to do.Any suggestion will be appreciated.Thanks in advance