My company is growing fast. I'm getting new servers and user accounts everyday. I need a good way to manage all these users across multiple servers fast(single sign-on would be nice). I looked into LDAP, Kerberos, IPA from redhat and even openID, there are just so many tools out there that i'm not sure which one to spend my time on.
Can somebody tell me what they use for their company or maybe some kind of suggestions?