just travel over to the developersite and find out what LDAP can do for you: bwong789 writes in the new article on PHP-Nuke.org "LDAP for PHP-Nuke provides user management via LDAP.
It includes a modified version of Usermanager, a web-based user management system, that can be used to synchronize PHP-Nuke user information with an LDAP database. The system also keeps synchronization with LDAP-based Samba support."