OpenLDAP is the open source implementation of the Lightweight Directory Access Protocol. The project is hosted at http://www.openldap.org and it counts Symas and Suretec as two of its main contributors.
OpenLDAP is a very flexible and powerful package, that requires much dedication to understand and implement. Although the documents on http://wiki.servergeeks.org may be a useful resource, we recommend you sign up to the OpenLDAP mailing lists, and follow the latest development. Due to the fast paced nature of Open Source development, many of the advanced features are enhanced in the most recent releases. Please also note that many of the distributions provide packages designed for client-side implementations of OpenLDAP, and are rarely suitable for running as a server.