Since Citrix XenApp / XenDesktop 7.9 the Federated Authentication Service (FAS) is available. Via Citrix FAS it is possible to authenticate a user via SAML and thus connect Citrix as a service provider to existing identity providers, such as Azure-AD.
Sequence of SAML authentication
- The user browse the FQDN (e.g. citrix.deyda.net) of the Citrix Gateway vServer (Service Provider) to start his VA / VD resources
- The Citrix Gateway vServer directs the unauthenticated user directly to the Identity Provider (Azure-AD) to authenticate itself (saml: authnRequest)
- The Identity Provider points to its SingleSignOnService URL (e.g. login.microsoftonline.com) and the user must authenticate
- The user enters his AD credentials and these are checked by the Identity Provider against the user database
- Upon successful verification in the user database, the IdP is informed
- The IdP issues a token (SAML assertion) and sends it to the Citrix Gateway (saml: response)
- Citrix Gateway checks the token (assertion signature) and extracts the UPN from the assertion token. This allows access via SSO to the VA / VD farm via FAS (The SP does not have access to the user’s credentials)