Lably
Skip to content

Lightweight Directory Access Protocol

Network protocol supporting distributed directory information services

  • 21 min read
  • 10 chapters

Related on Lably

Through Email, Information technology and Computer network

Lab · Class 10–11NLP PipelinesLab · Class 12Networking Basics

Directory services play an important role in developing intranet and Internet applications by allowing the sharing of information about users, systems, networks, services, and applications throughout the network. As examples, directory services may provide any organized set of records, often with a hierarchical structure, such as a corporate email directory. Similarly, a telephone directory is a list of subscribers with an address and a phone number.

A common use of LDAP is to provide a central place to store usernames and passwords. This allows many different applications and services to connect to the LDAP server to validate users.

LDAP is a simpler (lightweight) subset of the standards in the X.500 series, particularly the X.511 Directory Access Protocol. Because of this relationship, LDAP is sometimes called X.500 Lite.

The main components of LDAP are:

  • Protocol (RFC 4511): An application protocol that runs over an Internet Protocol (IP) network used to communicate with a directory service
  • Directory Information Models (RFC 4512): A specification for systems that implement directory services, i.e., "a collection of open systems cooperating to provide directory services"
  • Schema for User Applications (RFC 4519): A standard and extensible data schema for information to be help in a directory service - a "specification of attribute types and object classes intended for use by LDAP"

History

Telecommunication companies' understanding of directory requirements was well developed after some 70 years of producing and managing telephone directories. These companies introduced the concept of directory services to information technology and computer networking, their input culminating in the comprehensive X.500 specification, a suite of protocols produced by the International Telecommunication Union (ITU) in the 1980s.

X.500 directory services were traditionally accessed via the X.511 Directory Access Protocol (DAP), which required the Open Systems Interconnection (OSI) protocol stack. LDAP was originally intended to be a lightweight alternative protocol for accessing X.500 directory services through the simpler (and now widespread) TCP/IP protocol stack. This model of directory access was borrowed from the DIXIE and Directory Assistance Service protocols.

The protocol was originally created by Tim Howes of the University of Michigan, Steve Kille of Isode Limited, Colin Robbins of Nexor and Wengyik Yeong of Performance Systems International, circa 1993, as a successor to DIXIE and DAS. Mark Wahl of Critical Angle Inc., Tim Howes, and Steve Kille started work in 1996 on a new version of LDAP, LDAPv3, under the aegis of the Internet Engineering Task Force (IETF). LDAPv3, first published in 1997, superseded LDAPv2 and added support for extensibility, integrated the Simple Authentication and Security Layer, and better aligned the protocol to the 1993 edition of X.500. Further development of the LDAPv3 specifications themselves and of numerous extensions adding features to LDAPv3 has come through the IETF.

In the early engineering stages of LDAP, it was known as Lightweight Directory Browsing Protocol, or LDBP. It was renamed with the expansion of the scope of the protocol beyond directory browsing and searching, to include directory update functions. It was given its Lightweight name because it was not as network intensive as its DAP predecessor and thus was more easily implemented over the Internet due to its relatively modest bandwidth usage.

LDAP has influenced subsequent Internet protocols, including later versions of X.500, XML Enabled Directory (XED), Directory Service Markup Language (DSML), Service Provisioning Markup Language (SPML), and the Service Location Protocol (SLP). It is also used as the basis for Microsoft's Active Directory.

Sign in to keep reading

9 more chapters are free with a Lably account.

More in Computing and communication

ISBNUnique numeric book identifier since 1970X (social network)American social networking serviceWayback MachineDigital archive by the Internet ArchivePython (programming language)General-purpose programming languageMacOSOperating system for Apple computersUnicodeCharacter encoding standard