Shibboleth
Michael McNeill, Jonathan Champ, Michael Erlewine, Will Norris By Michael McNeill, Jonathan Champ, Michael Erlewine, Will Norris

October 31, 2023

Shibboleth Plugin

Allows WordPress to externalize user authentication and account creation to a Shibboleth Service Provider.

This plugin is designed to support integrating your WordPress site into your existing identity management infrastructure using a Shibboleth Service Provider.

WordPress can be configured so that all standard login requests will be sent to your configured Shibboleth Identity Provider or Discovery Service. Upon successful authentication, a new WordPress account will be automatically provisioned for the user if one does not already exist. User attributes (username, first name, last name, display name, nickname, and email address) can be synchronized with your enterprise’s system of record each time the user logs into WordPress.

Finally, the user’s role within WordPress can be automatically set (and continually updated) based on any attribute Shibboleth provides. For example, you may decide to give users with an eduPersonAffiliation value of faculty the WordPress role of editor, while the eduPersonAffiliation value of student maps to the WordPress role contributor. Or you may choose to limit access to WordPress altogether using a special eduPersonEntitlement value.

Contribute on GitHub

This plugin is actively maintained by michaelryanmcneill and the WordPress community, using GitHub. Contributions are welcome, via pull request, on GitHub. Issues can be submitted on the issue tracker.

Installation

Preface

First and foremost, this plugin requires you to have a Shibboleth Service Provider installed and functional on your web server. This can be done many ways, but that is outside the scope of this plugin. Once you’ve configured the Shibboleth Service Provider, you can proceed with installing the plugin.

This plugin supports both “lazy sessions” (where requireSession is set to false) and “required sessions” (where requireSession is set to true).

Upon activation, the plugin will attempt to set the appropriate directives in WordPress’s .htaccess file. You can prevent this from happening by defining the following wp-config.php constant:

define('SHIBBOLETH_DISALLOW_FILE_MODS', true);

Installation Process

Visit “Plugins > Add New”
Search for “Shibboleth”
Activate the Shibboleth plugin from your Plugins page.
Configure the plugin from the Shibboleth settings page.

OR

Upload the “shibboleth” folder to the /wp-content/plugins/ directory
Activate the Shibboleth plugin from your Plugins page.
Configure the plugin from the Shibboleth settings page.

Troubleshooting

If for some reason the plugin is unable to add the appropriate directives for Shibboleth, you can add the following to your .htaccess file.

AuthType shibboleth Require shibboleth

Screenshots

  1. Configure login, logout, and password management URLs

    Configure login, logout, and password management URLs

  2. Specify which Shibboleth headers map to user profile fields

    Specify which Shibboleth headers map to user profile fields

  3. Assign users into WordPress roles based on arbitrary data provided by Shibboleth

    Assign users into WordPress roles based on arbitrary data provided by Shibboleth

FAQ

What is Shibboleth?

From the Shibboleth Consortium:

Shibboleth is a standards based, open source software package for web single sign-on across or within organizational boundaries. It allows sites to make informed authorization decisions for individual access of protected online resources in a privacy-preserving manner.

How do I configure a Shibboleth Service Provider?

For more information on how to install the Native Shibboleth Service Provider on Linux, see this wiki article.

For more information on how to install the Native Shibboleth Service Provider on other operating systems, see this wiki article.

For more information on how to install Shibboleth on Nginx, see this GitHub repo.

Note, we cannot provide support for installation, configuration, or troubleshooting of Shibboleth Service Provider issues.

Can I extend the Shibboleth plugin to provide custom logic?

Yes, the plugin provides a number of new actions and filters that can be used to extend the functionality of the plugin. Search shibboleth.php for occurrences of the function calls apply_filters and do_action to find them all. Then write a new plugin that makes use of the hooks. If your require additional hooks to allow for extending other parts of the plugin, please notify the plugin authors via the support forum.

Before extending the plugin in this manner, please ensure that it is not actually more appropriate to add this logic to Shibboleth. It may make more sense to add a new attribute to your Shibboleth Identity Provider’s attribute store (e.g. LDAP directory), or a new attribute definition to the Identity Provider’s internal attribute resolver or the Shibboleth Service Provider’s internal attribute extractor. In the end, the Shibboleth administrator will have to make that call as to what is most appropriate.

Can I control the plugin settings with constants in wp-config.php?

Yes, the plugin allows for all settings to be controlled via constants in wp-config.php. If set, the constant will override the value that exists in the WordPress options table. The available constants are detailed (with their available options) below:

  • SHIBBOLETH_ATTRIBUTE_ACCESS_METHOD
    • Format: string
    • Available options: 'standard' for the default “Environment Variables” option, 'redirect' for the “Redirected Environment Variables” option, and 'http' for the “HTTP Headers” option.
    • Example: define('SHIBBOLETH_ATTRIBUTE_ACCESS_METHOD', 'standard');
  • SHIBBOLETH_ATTRIBUTE_ACCESS_METHOD_FALLBACK
    • Format: boolean
    • Available options: true to fallback to the standard “Environment Variables” options when the selected attribute access method does not return results or false to not fallback.
    • Example: define('SHIBBOLETH_ATTRIBUTE_ACCESS_METHOD_FALLBACK', true);
  • SHIBBOLETH_LOGIN_URL
    • Format: string
    • Available Options: none
    • Example: define('SHIBBOLETH_LOGIN_URL', 'https://example.com/Shibboleth.sso/Login');
  • SHIBBOLETH_LOGOUT_URL
    • Format: string
    • Available Options: none
    • Example: define('SHIBBOLETH_LOGOUT_URL', 'https://example.com/Shibboleth.sso/Logout');
  • SHIBBOLETH_PASSWORD_CHANGE_URL
    • Format: string
    • Available options: none
    • Example: define('SHIBBOLETH_PASSWORD_CHANGE_URL', 'https://sso.example.com/account/update');
  • SHIBBOLETH_PASSWORD_RESET_URL
    • Format: string
    • Available options: none
    • Example: define('SHIBBOLETH_PASSWORD_RESET_URL', 'https://sso.example.com/account/reset');
  • SHIBBOLETH_SPOOF_KEY
    • Format: string
    • Available options: none
    • Example: define('SHIBBOLETH_SPOOF_KEY', 'abcdefghijklmnopqrstuvwxyz');
  • SHIBBOLETH_DEFAULT_TO_SHIB_LOGIN
    • Format: boolean
    • Available options: true to automatically default to Shibboleth login or false to not default to Shibboleth login.
    • Example: define('SHIBBOLETH_DEFAULT_TO_SHIB_LOGIN', true);
  • SHIBBOLETH_AUTO_LOGIN
    • Format: boolean
    • Available options: true to automatically login users with an existing Shibboleth session or false to not check for an existing Shibboleth session.
    • Example: define('SHIBBOLETH_AUTO_LOGIN', true);
  • SHIBBOLETH_BUTTON_TEXT
    • Format: string
    • Available options: none
    • Example: define('SHIBBOLETH_BUTTON_TEXT', 'Login with Shibboleth');
  • SHIBBOLETH_DISABLE_LOCAL_AUTH
    • Format: boolean
    • Available options: true to prevent users logging in using WordPress local authentication or false allow WordPress local authentication AND Shibboleth authentication.
    • Example: define('SHIBBOLETH_DISABLE_LOCAL_AUTH', true);
  • SHIBBOLETH_HEADERS
    • Format: array (>= PHP 5.6) OR serialized string (< PHP 5.6)
    • Available options: none
    • PHP 5.5 (and earlier) example: define( 'SHIBBOLETH_HEADERS', serialize( array( 'username' => array( 'name' => 'eppn' ), 'first_name' => array( 'name' => 'givenName', 'managed' => 'on' ), 'last_name' => array( 'name' => 'sn', 'managed' => 'on' ), 'nickname' => array( 'name' => 'eppn', 'managed' => 'off' ), 'display_name' => array( 'name' => 'displayName', 'managed' => 'off' ), 'email' => array( 'name' => 'mail', 'managed' => 'on' ) ) ) );
    • PHP 5.6 (and above) example: const SHIBBOLETH_HEADERS = array( 'username' => array( 'name' => 'eppn' ), 'first_name' => array( 'name' => 'givenName', 'managed' => 'on' ), 'last_name' => array( 'name' => 'sn', 'managed' => 'on' ), 'nickname' => array( 'name' => 'eppn', 'managed' => 'off' ), 'display_name' => array( 'name' => 'displayName', 'managed' => 'off' ), 'email' => array( 'name' => 'mail', 'managed' => 'on' ) );
    • PHP 7.0 (and above) example: define('SHIBBOLETH_HEADERS', array( 'username' => array( 'name' => 'eppn' ), 'first_name' => array( 'name' => 'givenName', 'managed' => 'on' ), 'last_name' => array( 'name' => 'sn', 'managed' => 'on' ), 'nickname' => array( 'name' => 'eppn', 'managed' => 'off' ), 'display_name' => array( 'name' => 'displayName', 'managed' => 'off' ), 'email' => array( 'name' => 'mail', 'managed' => 'on' ) ) );
  • SHIBBOLETH_CREATE_ACCOUNTS
    • Format: boolean
    • Available options: true to automatically create new users if they do not exist in the WordPress database or false to only allow existing users to authenticate.
    • Example: define('SHIBBOLETH_CREATE_ACCOUNTS', true);
  • SHIBBOLETH_AUTO_COMBINE_ACCOUNTS
    • Format: string
    • Available options: 'disallow' for the default “Prevent Automatic Account Merging” option, 'allow' for the “Allow Automatic Account Merging” option, and 'bypass' for the “Allow Automatic Account Merging (Bypass Username Management)” option.
    • Example: define('SHIBBOLETH_AUTO_COMBINE_ACCOUNTS', 'disallow');
  • SHIBBOLETH_MANUALLY_COMBINE_ACCOUNTS
    • Format: string
    • Available options: 'disallow' for the default “Prevent Manual Account Merging” option, 'allow' for the “Allow Manual Account Merging” option, and 'bypass' for the “Allow Manual Account Merging (Bypass Username Management)” option.
    • Example: define('SHIBBOLETH_MANUALLY_COMBINE_ACCOUNTS', 'disallow');
  • SHIBBOLETH_ROLES
    • Format: array (>= PHP 5.6) OR serialized string (< PHP 5.6)
    • Available options: none
    • PHP 5.5 (and earlier) example: define( 'SHIBBOLETH_ROLES', serialize( array( 'administrator' => array( 'header' => 'entitlement', 'value' => 'urn:mace:example.edu:entitlement:wordpress:admin' ), 'author' => array( 'header' => 'affiliation', 'value' => 'faculty' ) ) ) );
    • PHP 5.6 (and above) example: const SHIBBOLETH_ROLES = array( 'administrator' => array( 'header' => 'entitlement', 'value' => 'urn:mace:example.edu:entitlement:wordpress:admin' ), 'author' => array( 'header' => 'affiliation', 'value' => 'faculty' ) );
    • PHP 7.0 (and above) example: define('SHIBBOLETH_ROLES', array( 'administrator' => array( 'header' => 'entitlement', 'value' => 'urn:mace:example.edu:entitlement:wordpress:admin' ), 'author' => array( 'header' => 'affiliation', 'value' => 'faculty' ) ) );
  • SHIBBOLETH_DEFAULT_ROLE
    • Format: string
    • Available options: All available WordPress roles. The defaults are 'administrator', 'subscriber', 'author', 'editor', and 'contributor'. Leave this constant empty '' to make the default no allowed access.
    • Example: define('SHIBBOLETH_DEFAULT_ROLE', 'subscriber');
  • SHIBBOLETH_UPDATE_ROLES
    • Format: boolean
    • Available options: true to automatically use Shibboleth data to update user role mappings each time the user logs in or false to only update role mappings when a user is initally created.
    • Example: define('SHIBBOLETH_UPDATE_ROLES', true);
  • SHIBBOLETH_LOGGING
    • Format: array (>= PHP 5.6) OR serialized string (< PHP 5.6)
    • Available options: account_merge, account_create, auth, role_update
    • PHP 5.5 (and earlier) example: define( 'SHIBBOLETH_LOGGING', serialize( array( 'account_merge', 'account_create', 'auth', 'role_update' ) ) );
    • PHP 5.6 (and above) example: const SHIBBOLETH_LOGGING = array( 'account_merge', 'account_create', 'auth', 'role_update' );
    • PHP 7.0 (and above) example: define('SHIBBOLETH_LOGGING', array( 'account_merge', 'account_create', 'auth', 'role_update' ) );
  • SHIBBOLETH_DISALLOW_FILE_MODS
    • Format: boolean
    • Available options: true to disable the Shibboleth plugin from attempting to add .htaccess directives or false to allow the Shibboleth plugin to add the necessary .htaccess directives.
    • Example: define('SHIBBOLETH_DISALLOW_FILE_MODS', true);

Changelog

version 2.4.3 (2023-10-31)

  • Compatibility: Check for Shibboleth username instead of Shib-Session-ID; thanks @spfncer #97
  • CI: Update GitHub Action workflows and code for WordPress coding standard v3 #94
  • Cleanup: Reduced duplication via a logging helper function #95

version 2.4.2 (2023-04-07)

  • Documentation: Updated Shibboleth documentation external links #92
  • Accessibility: Improve labels and heading structure on admin pages #92
  • Security: Improve input sanitization and use of nonces #92
  • CI: Switch GitHub Action workflows to check against WordPress coding standard #92

version 2.4.1 (2023-03-20)

  • Compatibility: Fix redirect_to issues on WordPress 6; thanks @masteradhoc, @caosborne89, @jakeparis #88
  • Accessibility: Improve color contrast on login page #89
  • Fix user profile to only show account link button to the user themself; thanks @jakeparis #90
  • CI: Add GitHub Action workflows to check against WordPress-Core coding standard #91

version 2.4 (2021-08-27)

  • Added hooks for hopefully rare cases where user overrides are necessary; thanks @dsXLII #74
  • Better login form support for WordPress 5.3; thanks @jakeparis #76
  • Spelling fixes; thanks @junaidkbr #72
  • General cleanup to better align with the WordPress Coding Standards #80

version 2.3 (2020-08-17)

  • Implementing a fallback option for the “Shibboleth Attribute Access Method”. For example, if your web server returns redirected environment variables, but occasionally returns standard environment variables, you would want to enable this option.
  • Removing deprecated create_function() from use.
  • Bumped minimum PHP and WordPress versions to 5.6 and 4.0 respectively.
  • Greatly improved the handling of managed fields and cleaned up options-user.php.

version 2.2.2 (2020-06-22)

  • Re-implementing conditional for .htaccess to protect against the Shibboleth Apache module not being installed; thanks to @jrchamp for reporting. This change includes conditionals for mod_shib, mod_shib.c, and mod_shib.cpp. If you run into issues related to this change, please open an issue on GitHub.

version 2.2.1 (2020-06-18)

version 2.2 (2020-06-17)

  • Implementing conditional for .htaccess to protect against the Shibboleth Apache module not being installed; thanks to @jrchamp for reporting.
  • Added an option to disable account creation if no mapped roles or default roles exist; props @dandalpiaz.
  • Improve the Shibboleth login link so that when it shows up on a normal request it will correctly still be a login link and will redirect back to the page that showed the login link; props @Alhrath.

version 2.1.1 (2018-05-16)

  • Minor code cleanup for disabling authentication and passsword resets; props @jrchamp.
  • Resolved a minor problem where setting the SHIBBOLETH_LOGGING constant on PHP 5.5 or below would not work in the administrative interface; props @jrchamp.
  • Resolved an issue with the default to shibboleth login option in the admin; thanks to @trandrew for reporting.

version 2.1 (2018-05-16)

version 2.0.2 (2018-01-17)

  • Resolved an issue that caused manual linking of accounts to fail if user’s didn’t have an existing Shibboleth session.

version 2.0.1 (2018-01-17)

  • Resolved a regression that prevented accounts from being created if they matched a group; thanks to @Androclese for reporting.
  • Resolved an issue where assets were not being properly included in the WordPress.org packaged plugin.

version 2.0 (2018-01-16)

  • Changed the way we check for Shibboleth attributes. Now, by default, we only check standard environment variables for Shibboleth attributes. For most users, no additional configuration will be necessary. If you are using a specialized server configuration, such as a Shibboleth Service Provider on a reverse proxy or a server configuration that results in environment variables being sent with the prefix REDIRECT_, you should instead select the option specific to your server configuration. Selecting the “Redirected Environment Variables” option will look for attributes in environment variables prefixed with REDIRECT_ while selecting the “HTTP Headers” option will look for attributes in environment variables (populated by HTTP Headers) prefixed with HTTP_. Most users should be fine leaving the default option selected; thanks to @jrchamp for reporting.
  • Changed the default behavior to not automatically update user roles.
  • Allow options to be defined via constants. Documentation has been added to the “FAQ” section of the WordPress.org plugins page.
  • Allow automatic and manual merging of local WordPress accounts with Shibboleth accounts. This prevents a collision from occurring if the Shibboleth email attribute matches an email that already exists in the wp_users table. This is configurable by an administrator.
  • Changed the options page to utilize a more modern design centered around tabs.
  • Added signifcant customizations to the login page to bring it more in-line with WordPress.com Single Sign On.
  • Disabled the sending of an email notifying user’s that their email had changed when the Shibboleth plugin updates user attributes to prevent user confusion; props @jrchamp.
  • Removed the shibboleth-mu.php file as it is no longer relevant.

version 1.8.1 (2017-09-08)

  • Use sanitize_title rather than sanitize_user to sanitize user_nicename; props @jrchamp.
  • Changed activation and deactivation hooks to use __FILE__; props @jrchamp.
  • Reverted to using $_SERVER in shibboleth_getenv() to handle use cases where getenv() doesn’t return data; thanks to @jmdemuth for reporting.

version 1.8 (2017-08-23)

The Shibboleth plugin is now being maintained by michaelryanmcneill. Contributions are welcome on GitHub!

  • Adding the ability to disable .htaccess modifications with a wp-config.php constant (SHIBBOLETH_DISALLOW_FILE_MODS).
  • Added shibboleth_getenv() to support various prefixed environment variables from Shibboleth, includingREDIRECT_ and HTTP_; props @cjbnc and @jrchamp.
  • Update various deprecated WordPress functions, including update_usermeta() and get_userdatabylogin(); props @skoranda.
  • Resolved undefined index when calling shibboleth_session_initiator_url(); props @skoranda.
  • Added support for PHP 7.x; props to many people.
  • Added shibboleth_authenticate_user filter; props @boonebgorges.
  • Resolved undefined index on admin-options.php; props @HirotoKagotani, @jrchamp, and @stepmeul.
  • Resolved HTML markup mistake; props @HirotoKagotani.
  • Adds an update success message to let user’s know their settings were saved, using the Settings API.

version 1.7 (2016-03-20)

version 1.6 (2014-04-07)

  • tested for compatibility with recent WordPress versions; now requires WordPress 3.3
  • options screen now limited to admins; props billjojo
  • new option to auto-login using Shibboleth; props billjojo
  • remove workaround for MU add_site_option; props billjojo

version 1.5 (2012-10-01)

  • Bugfix: check for Shib_Session_ID as well as Shib-Session-ID out of the box. Props David Smith

version 1.4 (2010-08-30)

  • tested for compatibility with WordPress 3.0
  • new hooks for developers to override the default user role mapping controls
  • now applies sanitize_name() to the Shibboleth user’s nicename column

version 1.3 (2009-10-02)

  • required WordPress version bumped to 2.8
  • much cleaner integration with WordPress authentication system
  • individual user profile fields can be designated as managed by Shibboleth
  • start of support for i18n. If anyone is willing to provide translations, please contact the plugin author

version 1.2 (2009-04-21)

  • fix bug where shibboleth users couldn’t update their profile. (props pchapman on bug report)
  • fix bug where local logins were being sent to shibboleth

version 1.1 (2009-03-16)

  • cleaner integration with WordPress login form (now uses a custom action instead of hijacking the standard login action)
  • add option for enterprise password change URL — shown on user profile page.
  • add option for enterprise password reset URL — Shibboleth users are auto-redirected here if attempt WP password reset.
  • add plugin deactivation hook to remove .htaccess rules
  • add option to specify Shibboleth header for user nickname
  • add filters for all user attributes and user role (allow other plugins to override these values)
  • much cleaner interface on user edit admin page
  • fix bug with options being overwritten in WordPress MU

version 1.0 (2009-03-14)

  • now works properly with WordPress MU
  • move Shibboleth menu to Site Admin for WordPress MU (props: Chris Bland)
  • lots of code cleanup and documentation

version 0.1

  • initial public release
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Details

  • Version: 2.4.3
  • Active installations: 3,000
  • WordPress Version: 4.0
  • Tested up to: 6.4.5
  • PHP Version: 5.6

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