Single-Sign-On into Moodle using Admidio as a SAML 2.0 Identity Provider

Starting with version 5.0, Admidio can be used by other applications to authenticate users against Admidios user base. These instructions will guide you through the process of connecting Moodle to Admidio to use Admidio's login. For general instructions, and other apps, please visit the general Single-Sign-On overview page.

There are several SAML plugins for Moodle. We will describe SAML login via the “SAML2 Single sign on” plugin. Unfortunately, that app does not (yet) use rule mapping (i.e. using Admidio groups to grant permission in Moodle).

There is also the SAML2 SSO Auth plugin, which depends on an separate installation of simpleSAMLphp. If you prefer this pugin, follow the instructions to set up SimpleSAMLphp with Admidio. Once SimpleSAMLphp is working, connecting the Moodle installation to SimpleSAMLphp using the SAML2 SSO Auth is rather straightforward.

Throughout the document we will assume you have both Admidio and Moodle already set up properly at https://admidio.local/ and https://moodle.local/. Please modify these URLs to your actual installation.

As a first step, one needs to configure Admidio to act as an SAML 2.0 Identity Provider (IdP). This has to be done once and is not specific to any client. Please follow this guide: #a_basic_setup_for_admidio_as_a_saml_id_provider

Basically, one (1) needs to create a cryptographic key to sign message and choose a unique EntityID. The page preferences https://admidio.local/modules/preferences.php?panel=sso also provides the link to the metadata xml, and the individual settings in case a client does not support auto-configuration via metadata.

Setting up a client (SAML “Service Provider” - short SP) to use Admidio's user accounts for logging in consists of two steps. If both the IdP (Admidio in our case) and the SP (Moodle in this document) support metadata loading, the setup is very straightforward and easy. Otherwise, one has to copy URLs manually to the client, but Admidio already provides these in a single place, so this situation is not as bad, either.

• At the Service Provider (SP) - Moodle in our case - install the extension to support SAML login.
• Configure it either with Admidio's XML metadata file, or enter the EntityID, the Single-Sign-On Endpoint, the SLO Endpoint and the public certificate manually (Admidio provides a simple table to copy these values from).
• Choose whether sent messages should be signed and/or encrypted (these features require an additional private key and certificate for the SP!), and whether received messages are checked for signatures or encryption is expected.
• In Admidio, create a new SAML client. If the SP provides a metadata URL, paste it and let Admidio automatically load the configuration from the SP. One can also manually paste these settings.
  • Choose an easily understood label for the client (only used in Admidio's list of clients, but has no technical use)
  • Enter the ClientID from the SP, as well as the ACS URL and the SLO response URL. These values must be provided by the client.
• In Admidio, also choose whether sent messages should be signed or encrypted. The crypto key generated in the general SAML setup will be used.
• Optionally select which profile fields should be mapped to SAML attributes and sent to the client, and configure which group memberships should be transmitted.

• Install the “SAML2 Single sign on” plugin from Moodle's plugin directory:

• After installing this plugin, go to the plugin list and scroll down to the “Authentication” section (or alternatively, use the URL https://[YOUR_MOODLE]/admin/settings.php?section=manageauths). The SAML plugin should be shown together with a link to the settings.

• Go to the plugin's settings (either via the link in the plugins page, or in the menu item “Plugins” → “Authentication” → “SAML2”.
  • The plugin supports auto-loading of Admidio's IdP settings. In particular, one only needs to copy the Metadata URL from Admidio to Moodle's plugin configuration, and the plugin will retrieve all endpoint URLs, the key and the signing/encryption settings automatically.
  • The “IdP label override” only governs the text displayed on the login button.
  • If one wants more than one SAML IdP as user backend, it is possible to configure each IdP with an alias to provide direct login links or tweak the display. Typically, this is not needed, except for special cases.
  • The plugin configuration allows the explicit generation of cryptographic certificates / keys for signing and encrypt. Usually the default is sufficient (a key is generated and used by moodle in any case).
• The next section in the Moodle plugin configuration screen provides a link to the SP metadata, which (after the plugin config is saved) provides Admidio with all relevant information to configure its connection with Moodle as a SAML2.0 IdP.
  • The Entity ID is the most relevant identifier that needs to match in Moodle's and Admidio's configuration, otherwise login to Moodle with SAML using Admidio as login backend will not be possible. If the field is left blank, the plugin will generate a unique identifier. One can also choose any other unique string, typically the URL of the Moodle installation.
  • The link to the SP metadata can be copied from the link using the right mouse button. Typically it is of the form https://[YOUR_MOODLE]/auth/saml2/sp/metadata.php. This URL will lalter be inserted into Admidio's configuration.
• SAVE the plugin configuration.

Once these basic SAML settings are done, I would recommend saving the plugin configuration and to set up the SP in Admidio. The remaining settings (transmitted fields, as well as signing/encryption requirements) are best done in parallel in Moodle and Admidio.

Now, return to Admidio's SSO preferences page, go to the “Single-Sign-On Client Administration” (the button right above the “Save” button), and create a new client.

Paste the metadata URL copied from Moodle into the corresponding input field at the top and click “Load Client Metadata”. This should load all settings from Moodle and pre-fill the following fields correctly. Only the Client Name needs to be entered. Choose any name to clearly identify the client in the list of SAML clients. There is no functionality depending on the name, but it will be displayed to the end user in the login form.

• If the Moodle config does not override the “Entity ID”, it will be the Metadata URL, which uniquely identifies the SAML client.
• The plugin config contains also several settings that tweak signing settings. Since the keys and certificates are automatically generated, one can choose whatever level of security is desired, but clearly the Moodle and Admidio settings need to be consistent for the login to work.
• The “Allow create” setting determines whether new users should be generated in Moodle when an unknown user successfully logs in through SAML.

The configuration of both Moodle and Admidio's SAML provides settings to want / require messages to be cryptographically signed to prevent security attacks. Choose your desired level of security, but make sure that the settings are consistent:

The plugin's configuration page also provides a mapping of SAML attributes to Moodle fields. Again, Admidio provides a similar mapping. Whatever information should be transferred from Admidio to Moodle should be configured. The actual SAML / IdP field name is not relevant, only the source Admidio field and the target Moodle field:

Moodle's SAML app only allows connecting existing users to a SAML account from Admidio. It does not have any functionality to create new users when an unknown account successfully logs in via SAML.

This means that one has to manually create all users that should have access to Moodle first, and then assign each one their proper SAML username. Only after that, single-sign-on via Admidio is possible.

First, you have to configure Admidio to use the “Login name - usr_login_name” as the “User ID field”.

Create each user, and in in the “Edit user” form, switch to the “SAML” tab, where you can create a new connection to a SAML account (click “Add a line”, select the Admidio IdP on the left and enter the Admidio username on the right).

Admidio and Moodle should now be set up to use Admidio for logging in to Moodle. If you log out of Moodle (or open Moodle in an incognito browser window) and go to the Moodle admin location, you should see the login screen with the choice of logging in with password or via SAML.

After choosing SAML login and loggin in with a user from Admidio, you should be logged in to Nextcloud.

• Moodle does NOT automatically create a new user account if a successful login from an unknown Admidio account occurs. Instead, one first has to create a new user (or connect an existing user) and connect that user with the proper Admidio user account name. In Admidio's SAML client config, you can select whether to use the numeric user ID, the login name or the email as “User ID field”. Whatever you choose determines which value must be entered in Moodle's user connection field.
• To install the SAML plugin, moodle needs the “pysaml2” library installed first. It can for example be installed from the shell with

  php3 install pysaml2

• If moodle is behind a reverse proxy (e.g. Nginx Proxy Manager), correct proxy settings both in Moodle and the proxy itself is vital to make sure that the SAML endpoints in the metadata file and the actually called endpoints actually use https. Otherwise, login will fail without a helpful error message.
  • In `moodle.conf` set

    proxy_mode = 1

  • Make sure the reverse proxy sends all proper proxy headers, including X-FORWARDED-HOST, which is used by moodle to detect a reverse proxy setup. Nginx Proxy Manager by default does not send this header. It is also not easily possible to add this header in the “Advanced” tab of the Proxy Host in NPM. Instead, one has to add Custom Location for “/” and set the X-Forwarded-Host header there via

    proxy_set_header X-Forwarded-Host $host;

    You need to duplicate the forwarding host information from the main host: