AD, OpenLDAP
 

Out of curiosity because I am trying to set it up, is there a an opensource solution for single signons. If I have users sign onto an AD domain, but I want to give them shell access is there a way to authenticate shell access with LDAP?
For example, I authenticate wireless users via WPA to a freeradius server that collects user credentials from an AD Domain Controller. If they want to get access to a shell by opening putty or something like that, can it authenticate via LDAP?

Yes, I think it is possible...we run LDAP Authentication for our shell server at work but as far as the details I will have to get back to you. Right now I am on spring break, so gimme a week til' I get back!