Security Assertion Markup Language (SAML) is an open standard for exchanging authentication and authorization data between one Identity Provider (IdP) and one or more Service Providers (SP). Both parties exchange messages using the XML protocol as transport. FortiGate firewall devices can be configured as both IdP or SP.
When Security Fabric is enabled, you can configure the root FortiGate as the IdP. You can also configure downstream FortiGates to be automatically configured as SPs, with all links required for SAML communication, when added to the Security Fabric. Administrator must still be authorized on each device. Credentials are verified by the root FortiGate, and login credentials are shared between devices. Once authorized, an administrator can move between fabric devices without logging in again.
Optionally, the downstream FortiGate can also be manually configured as an SP, and then linked to the root FortiGate.
The authentication service is provided by the root FortiGate using local system admin accounts for authentication. Any of the administrator account types can be used for SAML log in. After successful authentication, the administrator logs in to the first downstream FortiGate SP, and can then connect to other downstream FortiGates that have the SSO account properly configured, without needing to provide credentials again, as long as admins use the same browser session. In summary, the root FortiGate IdP performs SAML SSO authentication, and individual device administrators define authorization on FortiGate SPs by using security profiles.