52.2. How IdM incorporates logins via external IdPs
SSSD 2.7.0 contains the sssd-idp package, which implements the idp Kerberos pre-authentication method. This authentication method follows the OAuth 2.0 Device Authorization Grant flow to delegate authorization decisions to external IdPs:
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An IdM client user initiates OAuth 2.0 Device Authorization Grant flow, for example, by attempting to retrieve a Kerberos TGT with the
kinitutility at the command line. - A special code and website link are sent from the Authorization Server to the IdM KDC backend.
- The IdM client displays the link and the code to the user. In this example, the IdM client outputs the link and code on the command line.
The user opens the website link in a browser, which can be on another host, a mobile phone, and so on:
- The user enters the special code.
- If necessary, the user logs in to the OAuth 2.0-based IdP.
- The user is prompted to authorize the client to access information.
- The user confirms access at the original device prompt. In this example, the user hits the Enter key at the command line.
- The IdM KDC backend polls the OAuth 2.0 Authorization Server for access to user information.