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.

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.
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<li>Can the provided credentials be authenticated against LDAP?</li>
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<li>If so, is the LDAP user a member of the required LDAP groups (if any)?</li>
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<li>Does a matching WordPress user exist?</li>
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</ul>
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<li>If so, log the user in.</li>
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<li>If not, is user creation enabled?</li>
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<li>Create the user and log them in.</li>
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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.

OneLogin SAML SSO vs Simple LDAP Login