[定义，from wikipedia]
The Lightweight Directory Access Protocol, or LDAP (IPA: [ˈɛl dæp]), is an application protocol for querying and modifying directory services running over TCP/IP.[1]
A directory is a set of objects with similar attributes organized in a logical and hierarchical manner. The most common example is the telephone directory, which consists of a series of names (either of persons or organizations) organized alphabetically, with each name having an address and phone number attached. Due to this basic design (among other factors) LDAP is often used by other services for authentication.
An LDAP directory tree often reflects various political, geographic, and/or organizational boundaries, depending on the model chosen. LDAP deployments today tend to use Domain name system (DNS) names for structuring the topmost levels of the hierarchy. Deeper inside the directory might appear entries representing people, organizational units, printers, documents, groups of people or anything else which represents a given tree entry (or multiple entries).
Its current version is LDAPv3, which is specified in a series of Internet Engineering Task Force Standard Track Requests for comments (RFCs) as detailed in RFC 4510
[平台及软件]
再fedora 7上，从openldap.org下载目前stable的版本，从源代码安装。耗时约40分钟。
http://www.openldap.org/software/download/
[安装参考]
强烈建议先看官方的文档：http://www.openldap.org/doc/admin24/quickstart.html
[OpenLDAP学习资料]
LDAP for Rocket Scientists：http://www.zytrax.com/books/ldap/
[应用介绍]
LDAP Implementation HOWTO：http://www.faqs.org/docs/Linux-HOWTO/LDAP-Implementation-HOWTO.html
[附加软件]
GUI 的管理软件 Webmin：http://www.webmin.com/