To implement Zero Trust Network Access (ZTNA) where a FortiGate hub enforces device posture and processes traffic directly, specific architectural and configuration steps are required on the FortiGate appliance.

ZTNA Access Proxy (B): The FortiGate must be configured as a ZTNA access proxy. In this role, the FortiGate acts as a secure gateway that mediates connections between remote users and internal applications. This setup ensures that all TCP traffic is intercepted and processed by the FortiGate, providing a direct, shortest-path connection that bypasses the FortiSASE cloud PoPs for the data plane.

ZTNA Servers and Policies (C): Within the FortiGate configuration, administrators must define ZTNA servers (which identify the protected applications or resources) and ZTNA policies. ZTNA policies are the enforcement rules that check for valid client certificates and specific ZTNA tags (synchronized from FortiSASE) before allowing access to a resource. This configuration allows the FortiGate to perform continuous posture checks on every session.

Posture Check Mechanism: While ZTNA tags are used, they are generally synchronized from the FortiSASE Endpoint Management Service (EMS) rather than manually configured on the FortiGate itself. This synchronization ensures the FortiGate has real-time visibility into the security posture (e.g., AV compliance, OS version) of the endpoints as reported by FortiClient.

Analysis of Incorrect Options:

Option A: Creating ZTNA tags manually on a FortiGate is technically possible but is not the recommended "setup" in a FortiSASE deployment, as tags are meant to be dynamically assigned by EMS and synced to the fabric.

Option D: "Private access policies on FortiSASE" refers to the SD-WAN Secure Private Access (SPA) use case. In the SD-WAN SPA model, traffic is steered through the FortiSASE PoP first, whereas the requirement specifically asks for TCP traffic to be processed by the FortiGate using ZTNA.