drahkar

This plugin allows WordPress to authenticate users against an Active Directory. 
Developed to be compatible with current Active Directory releases as well as allow 
for Enterprise level Forest Deployments by allowing you to enter custom BaseDNs.
If you have bugs, suggestions, desires or requirements that you would like to see added 
to this, please come to the plugin page and submit them there so I can keep track 
of them as they are found and resolved.
This plugin is redeveloped off of <a href="https://wordpress.org/extend/plugins/simple-ldap-authentication/" rel="ugc">Simple LDAP 
Authentication</a>.
<h4>How to use</h4>
You can use this plugin in a few different ways.
<ol>
<li>
You can create WordPress accounts which match the names of your Active Directory accounts, and create these users from within the WordPress Users panel. Only the users you create in WordPress will be able to log in.
</li>
<li>
You can tick a checkbox so that anyone who can authenticate via Active Directory can log on. A WordPress account will be automatically created for the user if one does not already exist, with the default user role.
</li>
<li>
You can list the names of Active Directory groups who you want to allow to log on to WordPress. For each group in Active Directory, you can specify a corresponding WordPress user role.
</li>
</ol>
You can also combine the above however you like.

Simple AD Authentication

Authenticates users through Active Directory.

Clifton Griffin

Having a single login for every service is a must in large organizations. This plugin allows you to integrate WordPress with LDAP quickly and easily. Like, really really easy.
Contributing 
This is a community project now. Most development is done by users like you who find bugs and fix them, or find new ways to make the plugin more powerful for everyone.
The easiest way to contribute to this plugin is to submit a GitHub pull request. Here’s the repo: 
https://github.com/clifgriffin/simple-ldap-login
Support
If you need support, file an issue here: 
https://github.com/clifgriffin/simple-ldap-login/issues
Special Requests
If you need a customization or change specific to your install, I am available for hire. Shoot me an e-mail: clifgriffin[at]gmail.com
<h4>Features</h4>
<ul>
<li>Supports Active Directory and OpenLDAP (and other directory systems which comply to the LDAP standard, such as OpenDS)</li>
<li>Supports TLS</li>
<li>Uses up-to-date methods for WordPress authentication routines.</li>
<li>Authenticates existing WordPress usernames against LDAP.</li>
<li>Can be configured to automatically create WordPress users for valid LDAP logins.</li>
<li>You can restrict logins based on one or more LDAP groups.</li>
<li>Intuitive control panel.</li>
</ul>
<h4>Architecture</h4>
Simple LDAP Login adds an authentication filter to WordPress that authentication requests must pass. In doing so, it makes several decisions.
<ul>
<li>Can the provided credentials be authenticated against LDAP?</li>
<li>
<ul>
<li>If so, is the LDAP user a member of the required LDAP groups (if any)?</li>
</ul>
</li>
<li>
<ul>
<li>
<ul>
<li>Does a matching WordPress user exist?</li>
</ul>
</li>
</ul>
</li>
<li>
<ul>
<li>
<ul>
<li>
<ul>
<li>If so, log the user in.</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
<li>
<ul>
<li>
<ul>
<li>
<ul>
<li>If not, is user creation enabled?</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
<li>
<ul>
<li>
<ul>
<li>
<ul>
<li>
<ul>
<li>Create the user and log them in.</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
</ul>
This is high level overview. This should answer the philosophical questions about how the plugin works. If the plugin is unable to authenticate the user, it should pass it down the chain to WordPress. (Unless LDAP Exclusive is turned on, in which case it won’t.)

Simple LDAP Login

Integrating WordPress with LDAP shouldn't be difficult. Now it isn't. Simple LDAP Login provides all of the features, none of the hassles.

Simple AD Authentication vs Simple LDAP Login