Aaron Axelsen

LDAP authentication is configured on a site-wide (as opposed to per-blog) level, so only Network Admin accounts have access to the configuration to LDAP connection information.
Please make sure you have PHP compiled with LDAP support. This will show up as an LDAP section in your phpinfo() if it is correct.
Remember – all the code for the plugin was contributed by volunteers, and you can show your gratitude by giving back to the community!
<h3>How It Works</h3>
When enabled, this plugin can automatically create WordPress user accounts and blogs for LDAP-authenticated users. Assuming user credentials authenticate against the LDAP server, creating local accounts and blogs follows this 
algorithm:
Create a new WPMU User, with LDAP username and a randomly generated password. 
Some user information, such as first and last name, is extracted from the 
 information returned from the LDAP server. 
Actions for user creation and activation are triggered. 
The user’s domain / URL are created depending on plugin configuration (i.e., 
 VHost vs SubDir). 
If the option is set, a blog is created, with path and name based on the LDAP 
 username and the blog is activated with the user being Administrator, and 
 appropriate actions are triggered.
It should be noted that even though a random password is created for a user (for WPMU accounts), it is never displayed to the user. This is intentional so that there is no confusion as to which password should be used; it will always be using LDAP credentials. As a result, though, if ever LDAP is disabled or if the server is unavailable, users created with LDAP authentication will be unable to log in unless their passwords are reset.

WPMU Ldap Authentication

A plugin to override the core WordPress authentication method in order to use a LDAP server for authentication.  Currently only supported on MultiSite …

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.

WPMU Ldap Authentication vs Simple LDAP Login