Curtiss Grymala

This plugin allows WordPress to authenticate, authorize, create and update against an Active Directory domain. This plugin is based heavily on the <a href="https://wordpress.org/extend/plugins/active-directory-integration/" rel="ugc">Active Directory Integration</a> plugin, but has been modified to work with Multi Site and even Multi Network installations of WordPress.
Some of the features included in this plugin are:
<ul>
<li>authenticate against more than one AD Server (for balanced load)</li>
<li>authorize users by Active Directory group memberships</li>
<li>auto create and update users that can authenticate against AD 
mapping of AD groups to WordPress roles</li>
<li>use TLS (or LDAPS) for secure communication to AD Servers (recommended)</li>
<li>use non standard port for communication to AD Servers</li>
<li>protection against brute force attacks</li>
<li>user and/or admin e-mail notification on failed login attempts</li>
<li>determine WP display name from AD attributes (sAMAccountName, displayName, description, SN, CN, givenName or mail)</li>
<li>enable/disable password changes for local (non AD) WP users</li>
<li>WordPress 3.0/3.1 compatibility, including Multi Site and Multi Network</li>
</ul>
This plugin is based on <a href="https://wordpress.org/extend/plugins/active-directory-integration/" rel="ugc">glatze’s Active Directory Integration</a> plugin, which is based upon <a href="https://wordpress.org/extend/plugins/active-directory-authentication/" rel="ugc">Jonathan Marc Bearak’s Active Directory Authentication</a> plugin and <a href="http://adldap.sourceforge.net/" rel="nofollow ugc">Scott Barnett’s adLDAP</a>, a very useful PHP class.
Aside from the changes to make this plugin work more effectively with WordPress Multi Site, this version of the plugin also encrypts the password used to connect to the AD server when it is stored in the database.
This plugin was developed by <a href="https://wordpress.org/extend/plugins/profile/cgrymala" rel="ugc">Curtiss Grymala</a> for the <a href="http://umw.edu/" rel="nofollow ugc">University of Mary Washington</a>. It is licensed under the GPL2, which basically means you can take it, break it and change it any way you want, as long as the original credit and license information remains somewhere in the package.
<h3>Important Notice</h3>
Since I don’t currently have access to multiple AD servers, this plugin has only been tested on a single installation of WordPress with a single AD server. Therefore, it is entirely possible that there are major bugs.
At this time, I am seeking people to test the plugin, so please report any issues you encounter.
<h3>Requirements</h3>
<ul>
<li>
This plugin requires WordPress. It might work with versions older than 3.0, but it has not been tested with those.
</li>
<li>
This plugin also requires PHP5. Some attempt has been made to make it compatible with PHP4, but it has not been tested in that environment.
</li>
<li>
This plugin requires LDAP support to be compiled into PHP. If the <code>ldap_connect()</code> function is not available, this plugin will output an error message and will not do anything.
</li>
</ul>
<h3>To Do</h3>
<ul>
<li>Add ability to validate against multiple AD servers (check one, then the other – rather than just load-balancing as the plugin currently does)</li>
<li>DONE as of 0.4a – Update admin interface to utilize native meta box interface rather than custom layout</li>
<li>DONE as of 0.3a – Separate the profile information from the role equivalent groups in the “auto update user” setting</li>
</ul>

Active Directory Authentication Integration

Allows WordPress to authenticate, authorize, create and update users through Active Directory

onelogin

This SAML plugin eliminates passwords and allows you to authenticate WordPress users (typically editors) against your existing Active Directory or LDAP server as well increase security using YubiKeys or VeriSign VIP Access via OneLogin. OneLogin is pre-integrated with thousands of apps and handles all of your SSO needs in the cloud and behind the firewall.
<ul>
<li>Eliminate passwords in WordPress</li>
<li>Allow users to sign into WordPress with their Active Directory or LDAP credentials</li>
<li>Give users one-click access from your intranet</li>
<li>Increase security using browser PKI certificates or two-factor authentication from Yubico or VeriSign</li>
<li>Easily prevent access from former employees and contractors</li>
</ul>
If you used this plugin before 2.2.0 with just-in-time provision active, Read: https://wpvulndb.com/vulnerabilities/8508 
To mitigate that bug, place the script at the root of wordpress and execute it (later remove it) https://gist.github.com/pitbulk/a8223c90a3534e9a7d5e0a93009a094f

OneLogin SAML SSO

This plugin provides single sign-on via SAML and gives users one-click access to their WordPress accounts from identity providers like OneLogin.

Active Directory Authentication Integration vs OneLogin SAML SSO