The enterprise-class Open Source LDAP server for Linux. It is
hardened by real-world use, is full-featured, supports multi-master
replication, and already handles many of the largest LDAP
deployments in the world.

Key Features

* 4-Way Multi-Master Replication, to provide fault tolerance and
high write performance.

* Scalability: thousands of operations per second, tens of
thousands of concurrent users, tens of millions of entries,
hundreds of gigabytes of data.

* The code base has been developed and deployed continuously by
the same team for more than a decade.

* Extensive documentation, including helpful Installation and
Deployment guides.

* Active Directory user and group synchronization.

* Secure authentication and transport (SSLv3, TLSv1, and SASL)

* Support for LDAPv3

* On-line, zero downtime, LDAP-based update of schema,
configuration, management and in-tree Access Control Information
(ACIs).

* Graphical console for all facets of user, group, and server
management.