What Is Linux LDAP Authentication?

Lightweight Directory Access Protocol (LDAP) is a system that enables applications and programs to query user credentials or information rapidly. It is a client-server protocol often used for accessing directory services. Notably, this lightweight protocol is handy for accessing X.500-based directory services.

For example, someone within your systems wants to send mail to a new colleague and print the correspondences from a new printer. LDAP will only query the user identity and make the two services possible. The essence is that employees can use LDAP to verify passwords, connect to printers, or switch to Google for email services.

This article introduces you to Linux LDAP. So, it will define Linux LDAP and discuss the concept of Linux LDAP entries. The article will also provide a tutorial on how Linux LDAP works.

Let’s go!

What Is Linux LDAP?

LDAP comes in handy as an open, vendor-neutral protocol for storing, maintaining, and accessing directory data. It allows systems and users to access centrally-stored data or information over a network. LDAP also comes in handy in authenticating users and allowing users to access their system accounts from any machine within the network.

Organizations can, therefore, use LDAP to store and manage usernames, passwords, printer connections, email addresses, phone numbers, network services, authentication data, and an array of other static data in directories.

Lightweight Directory Access Protocol, as the name suggests, is a protocol. It is not an authentication protocol per se. Instead, you can use it to store and quickly search authentication operations.

So, rather than specifying how directory services and programs work, it functions as a form of language. Thus, allowing users to find the data and information they need instantly.

Linux LDAP Entries

Generally, directories are databases optimized to read, browse, and search. They contain various types of information and provide support for an array of sophisticated filtering capabilities.

LDAP is lightweight and does not support complicated rollback schemes or transactions synonymous with database management systems that handle high-volume and complex tasks. Directory updates are generally simple with no or very minimal changes.

The information model for Linux LDAP focuses on entries, a collection of attributes with a unique Distinguished Name (DN). Usually, a DN is often used to refer to entries unambiguously since each attribute of an entry has a type and at least one value.

Since it is a vendor-neutral protocol, LDAP is useable with various directory programs. A typical directory will often contain data/information of the following categories:

  • Descriptive Data – These are multiple points that collectively define an asset. They include names and locations.
  • Static Data – This is an information category that rarely changes. Even when they do, the deviations are pretty subtle.
  • Valuable Data – This category of data is integral to the functioning of a business or company. Often, this data should be accessible as it is useable repeatedly.

Ideally, the Lightweight Directory Access Protocol is not new. And despite having been published in 2003, LDAP remains widespread and useable across various platforms.

How Linux LDAP Works

Linux LDAP stands out as a querying mechanism. With Linux LDAP in your organization, an average employee will connect with the protocol dozens of times daily. And while the steps are pretty complex and can be taxing, an average employee will not know what it takes to make the connection.

An LDAP query involves the following processes:

  • Session Connection – This is the first step. It involves a user connecting to the server or system through an LDAP port.
  • Request – The user sends or submits a query to the server. A query could be a login request or an email lookup.
  • Response – The LDAP protocol does a search relating to the query in the directory, fetches the correct information, and gives feedback to the user.
  • Completion – The user ends the session by disconnecting from the LDAP port.

While the previous search process looks simple, a lot of coding is at stake to make it successful. Developers and system administrators have to determine the processing duration for the server, the size search limit, the variables worth including, and many other considerations. Thus, configuring your LDAP will determine how your search process responds.

Of course, Linux LDAP must authenticate the user before any search process to ensure that only authorized entities initiate searches. The two primary systems that LDAP uses to authenticate users include:

  • Simple Authentication Process – This involves a correct username and password.
  • Simple Authentication and Security Layer (SASL) – This is a secondary authenticating service like the Kerberos protocol. It performs a connection before a user gains a connection to the server.

Users can perform searches from the technological devices within the company. Yet, it is also possible to send queries from smartphones, laptops, or home computing devices. Ideally, LDAP communication happens without encryption or scrambling, which can cause a security threat. Many organizations use Transport Layer Security or TLS to prevent leakage or interception of LDAP messages.

Other operations you can accomplish with LDAP besides searching include adding, deleting, comparing, and modifying entries.


That brings us to the end of our introductory topic on LDAP. While this is an incredibly broad but essential area for system administrators, we compressed it to ensure that we address all the concerns. Still, the performance of your LDAP will depend on how you configure LDAP into your systems and how you use it.

About the author

Kennedy Brian

Brian is a computer scientist with a bias for software development, programming, and technical content development. He has been in the profession since 2015. He reads novels, jogs, or plays table tennis whenever not on gadgets. He is an expert in Python, SQL, Java, and data and network security.