LDAP or Lightweight Directory Access Protocol is a type of application protocol used for accessing and maintaining distributed directory information services over an IP network. Being a directory service, LDAP is used in organizations to store set of records in a hierarchical manner representing the physical structure of organization in a logical manner. LDAP directory service has an advantage over other type of files is that information about users and groups can be stored on a single server which can be centrally administered. This principle eliminates the need of replicating the user information. Furthermore, LDAP can be used to other information apart from user data and is compatible with multiple platforms.
Active Directory is based on the LDAP protocol and can be set up to manage the authentication of Active Directory objects like users, groups and computers along with their session information and home directories.
Authentication is a must for the LDAP client to access the LDAP services. In LDAP authentication the client must provide information to the server about the objects who will be accessing the server data and the server must provide the client the access rights. Upon successful client authentication, the server would check the access rights of the client each time a request is send.
LDAP authentication is supplied by the ‘Bind’ operation. LDAPv3 supports three types authentication, viz., Anonymous, Simple and SASL.
- A client that sends a request without doing a Bind operation is treated as an anonymous client and the process is termed as Anonymous Authentication.
- In Simple Authentication, the client has to send a fully qualified DN along with its clear-text password to perform a Bind operation. Usually an encrypted channel, SSL, is used while sending the client password so that it is not deciphered anywhere in the network.
- In SASL (Simple Authentication and security Layer) Authentication is used during connection based protocols. For SASL authentication, a protocol includes a command which identifies and authenticates a user to a server. There is also an optional command for negotiating protection of subsequent protocol interactions that results in the insertion of a protocol layer between the protocol and the connection. Through this, LDAP client and server can negotiate the possible use of customized non-standard mechanisms for authentication such as Kerberos.
Other than the three types of authentication discussed above, there is also a Mutual Authentication, wherein, the LDAP server’s identity is verified. Certain applications require authentication of the LDAP server and participate in the process called mutual authentication where both the parties participates in the exchange authenticate.
Lepide Active Directory Management and Reporting tool makes use of LDAP authentication every time an AD user is being created or a mapped user account is being located. The security Identity Mapping functionality of LADMR enables administrators to map user account names in two networks with different identities in Windows-based and UNIX-based domains, by specifying the LDAP path. This functionality of user name mapping utilizes Active Directory LDAP authentication.
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