Chapter 3 Authentication for FortiOS 5.0 : Agent-based FSSO : Configuring FSSO on FortiGate units : Enabling guest access through FSSO security policies
  
Enabling guest access through FSSO security policies
You can enable guest users to access FSSO security policies. Guests are users who are unknown to the Windows AD or Novell network and servers that do not logon to a Windows AD domain.
To enable guest access in your FSSO security policy, add an identity-based policy assigned to the built-in user group FSSO_Guest_Users. Specify the services, schedule and protection profile that apply to guest users — typically guests receive reduced access to a reduced set of services. See “Creating security policies”.