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This module provide single sign-on capability for your Drupal site by implementing the CAS protocol. CAS has quickly become the most popular single sign-on solution for universities. In its most simple use (CAS can also proxy single sign-on), a CAS server authenticates users and sends the user to the requested application (your Drupal site) with a special ticket. The application (your Drupal site) is then responsible for authenticating the ticket (behind the scenes, with a tool like cURL) and automatically logging the user in if the ticket is valid.

Here are some features of this module:

  • Configure the details of the CAS server to use for authentication
  • Supports CAS servers that implement protocol version 1.0 and 2.0, or a server implementing the SAML 1.1 protocol (D6 and D7 only)
  • Optionally enable the "CAS Gateway" feature to seamlessly log a user in if they have an active CAS server session
  • Optionally force users to authenticate (via CAS) for a specific set of pages
  • Optionally auto-register users that log in via CAS for the first time
  • Drupal 6/7 only: Optionally change appearance and behavior of Drupal's standard login form to instead provide a button to have users authenticate with CAS (standard Drupal authentication is always preserved). The Drupal 8 version provides a simple link on the existing login form.
  • Optionally use your Drupal site as a CAS proxy, allowing you to authenticate to other services on behalf of the user

Additionally, the Drupal 6 and 7 versions of this module ship with a sub-module that allows your Drupal site to instead act as a CAS server (allowing other websites to use it as the single sign-on source. The CAS server sub-module has been removed from this project in Drupal 8 in favor of the entirely separate cas_server module.


Please refer to the README file for specific installation and configuration instructions.


The Drupal 6 and Drupal 7 versions of this module depend on the phpCAS library. This library must be added to your Drupal site. Specific instructions exist in the README file for 6.x and 7.x versions. The Drupal 8 version depends on the External Auth module.

LDAP & CAS Attributes Integration

Integration with LDAP and CAS attributes is provided by a separate CAS Attributes module.

Upgrade notes

There is no upgrade path from major versions. You must manually re-configure the module when upgrading your site from Drupal 6 -> 7 -> 8. This is fairly painless, as the module only provides a single administration page with few fields to fill in for basic use cases.

Drupal 8 Version

The Drupal 8 version is under active development and now has a beta release.

Project information