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OpenID Connect Single Log Out (SLO)#

The Gluu Server uses OpenID Connect to end sessions for logout. Usually a logout link is provided to the connected SP and the session is killed inside the IDP.

When using OpenID Connect Logout, it is recommeneded to use Front-Channel Logout. In Front-Channel Logout the browser receives a page with a list of application logout urls within an iframe. This prompts the browser to call each application logout individually and the OpenID Connect end-session endpoint via Javascript.

The workflow for single logout for two applications using OpenID Connect Front-Channel Logout would be the following:

  1. App-A - registers frontchannel_logout_uri_1

  2. App-B - registers frontchannel_logout_uri_2

  3. App-A - login to the Authorization Server (AS), in this case the Gluu Server.

  4. App-B - login to AS (SSO)

  5. App-A - calls /end_session

  6. AS - returns back HTML with iframes where each iframe points to all frontchannel_logout_uris within this session, in our case it is frontchannel_logout_uri_1 and frontchannel_logout_uri_2

  7. Browser loads HTML (with all iframes, so it calls frontchannel_logout_uri_1 and frontchannel_logout_uri_2)

  8. App-A does not know anything about frontchannel_logout_uri_2, it just calls /end_session endpoint and it's the responsibility of the AS to track it and return the correct HTML page with iframes (once iframe is loaded, it means that frontchannel_logout_uri_2 is called and app-B must log itself out).

There are a few important points to note:

  1. post_logout_redirect_uri is not mandatory in the OpenID Connect Session Management specification, but the spec also says The value MUST have been previously registered with the OP. We have dual behavior description directly in specification. oxAuth ends session successfully (if session is present in OP) independently from whether post_logout_redirect_uri is valid or not. If it's not valid (or not provided) oxauth will NOT perform redirect. If redirect is required, post_logout_redirect_uri MUST be provided. If it is not provided then the server returns 400 with message Session is ended successfully but redirect to post logout redirect uri is not performed because it fails validation, and error post_logout_uri_not_associated_with_client. oxAuth considers end session without redirect as not proper behavior, however it's still up to each RP whether or not to use a redirect.

  2. id_token_hint and session_id parameters are optional. Therefore OP will end session successfully if these parameters are missed. However from other side if RP included them in request OP validates them and if any of those are invalid OP returns 400 (Bad Request) http code.

  3. id_token_hint and session_id parameters are optional. Therefore OP will end session successfully even if these parameters are not present. However, from if the RP includes them in the request and the OP validates them, and if any of those are invalid, the OP will return a 400 (Bad Request) http code. post_logout_redirect_uri is validated against the client which takes part in SSO. If a session does not exist, or can not be identified, then an error page is shown. However it is possible to allow a redirect to the RP without validation if allowPostLogoutRedirectWithoutValidation is set to true, and it is white listed via clientWhiteList (by default * wildcard is used which makes it white listed).

Read the OpenID Connect Front-Channel Logout Specifications to learn more.

SAML Logout#

Gluu Server now supports SAML2 Single Logout. Once it's enabled by the adminstrator, the logout URL is https://[hostname]/idp/Authn/oxAuth/logout. This logout link of IDP must have to be called from SP side.

The user will be directed to the following confirmation page.

SAML2 SLO Confirmation Page

CAS Logout#

CAS Logout can be performed by allowing CAS apps to participate in Gluu Server's SLO. If you want to make your CAS apps appear in SLO area, you have to add p:singleLogoutParticipant="true" while registering your CAS app in Gluu Server. As for example the bean of test CAS app ( ) can be registered like below.

                <bean class="net.shibboleth.idp.cas.service.ServiceDefinition"
                      p:singleLogoutParticipant="true" />

After that, CAS app logout can be called with same Gluu Server's SLO link which is https://[hostname]/idp/Authn/oxAuth/logout

Customizing Logout#

It is possible to use a custom authentication script to call individual logout methods for both SAML and OpenID Connect and log out of the desired SP/RPs when the user logs out of the Gluu Server. Please see the Custom Script Guide to start writing your own custom scripts.