First, let’s define a couple of terms that are important to this setup.
SP – Service Provider – This is the system that users are trying to log into, which in this setup is Drupal. The Drupal site is providing a ‘service’ and as such users want to authenticate with it. Service providers will generally create a local user to track the user within the site, although that’s not always the case.
IdP – Identity Provider – The SimpleSAMLphp system holds the information about the users and is therefore called an identity provider as it provides the identity of the user. This is used by the Service Provider to authenticate the user.
What we need to do here is setup SimpleSAMLphp so that it has information about users and be the IdP. Then setup Drupal so that users can authenticate against SimpleSAMLphp and log into the site as a SP. You will see the terms SP and IdP thrown about a lot when people talk about SAML and other authentication systems, but this is essentially what we are trying to achieve here.
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