LDAP support libraries
http://www.openldap.org/

OpenLDAP is an open source suite of LDAP (Lightweight Directory Access
Protocol) applications and development tools. LDAP is a set of
protocols for accessing directory services (usually phone book style
information, but other information is possible) over the Internet,
similar to the way DNS (Domain Name System) information is propagated
over the Internet. The openldap package contains configuration files,
libraries, and documentation for OpenLDAP.