Just a simple question; this question is not meant to attack Windows or start a flame war in anyway. I want a viable solution to the way authentication is done in Windows DC environment (LDAP) on *nix. I just want to know if OpenLDAP can be that solution?
Microsoft Active Directory is (mainly) just an LDAP server, some pre-cooked schemas and some tools for interacting with it and Kerberos. OpenLDAP is pretty much a drop-in replacement for the former.
While you could design your own AD compatible schemas (or if you already have an AD schema, just import it into openLDAP) and write your own tools for managing the datasets there are solutions runing on top of openLDAP available, e.g. GoSA, freeIPA see the samba wiki for more stuff
Not sure where Samba 4 has got to (its expected to add drop-in replacement functnioality for MSAD).