Lightweight Directory Access Protocol (LDAP)
LDAP, which stands for Lightweight Directory Access Protocol, is an open, vendor-neutral, industry standard application protocol. It is a client-server protocol that provides a way for authorized users to access and manage distributed directory information, such as email addresses, phone numbers, and the like.
LDAP started as a protocol based on X.500, a directory service standard. It was developed to make it easier and more efficient to access directory information over TCP/IP networks, which were rapidly becoming more prevalent than traditional X.25 networks.
LDAP is widely used in enterprise environments for managing user authentication and authorization, as well as for storing and retrieving contact information for employees, customers, and partners. It is also used in many other scenarios where distributed directory information needs to be accessed and managed, such as in online address books, email clients, and instant messaging applications.
How LDAP Works
LDAP is built around the concept of a directory, which is a hierarchical structure of entries that contain attribute-value pairs. Each entry corresponds to an object, such as a user, a group, an organizational unit, or a resource, and has a unique identifier called a distinguished name (DN).
The LDAP protocol defines a set of operations that can be used to perform various actions on directory entries, such as adding, modifying, deleting, and searching for entries. These operations are sent by LDAP clients to LDAP servers, which process the requests and return the results.
LDAP clients and servers communicate over a TCP/IP network using a binary format. LDAP messages are sent over a connection-oriented transport protocol, such as TCP, and are encoded using the Basic Encoding Rules (BER) of the Abstract Syntax Notation One (ASN.1) standard.
LDAP provides a simple and flexible authentication mechanism based on a bind operation, which allows clients to authenticate themselves to servers using various authentication methods, such as simple authentication, SASL, or SSL/TLS.
LDAP Implementations
LDAP is implemented by many vendors, including Microsoft, IBM, Oracle, Novell, and OpenLDAP, which is an open-source implementation of LDAP. These implementations provide LDAP server and client software that can be used to create and manage LDAP directories, as well as to access directory information.
LDAP directories can be integrated with other directory services, such as Active Directory, to provide a single sign-on (SSO) solution for users in heterogeneous environments. LDAP can also be used with various security protocols, such as Kerberos and SSL/TLS, to provide secure access and transmission of directory information.
Conclusion
LDAP is a powerful and flexible protocol for managing distributed directory information. It provides a standardized way of accessing and managing directory information over TCP/IP networks, and is widely used in enterprise environments for managing user authentication and authorization, as well as for storing and retrieving contact information for employees, customers, and partners.
LDAP implementations are available from many vendors, and can be integrated with other directory services to provide a single sign-on solution for users in heterogeneous environments. If you need to manage directory information in your organization, LDAP is definitely worth considering.