Moodle core allows admins to configure auth backends which provide SSO functionalities to the Moodle users. One of the most important auth backends with this SSO functionality is OAuth2.

If you add OAuth2 to your Moodle instance, an additional login button will appear on the login page which allows users to login via OAuth instead of logging in with the Moodle login form. By design, the URL of this OAuth button on the login form contains the Moodle sesskey which is bount to an active Moodle session.

Because of this design choice, admins who want to link from external websites (like corporation portals) to Moodle and want the users to be directly logged in via SSO, do not have a possibility to realize this goals with Moodle core tools. This tool solves this problem by providing such a persistent SSO URL within Moodle. Additionally, as the SSO login into Moodle will happen really transparently for the user, the tool makes sure that the users can't be maliciously redirected to any Moodle page / URL after the SSO login so that CSRF attacks are avoided.

Please see README file for details about the usage and features of this plugin.