Comprehensive and Detailed 150 to 250 words of Explanation From Palo Alto Networks Network Security Analyst Knowledge:
To enforce identity-based access when a user's identity is not automatically known (e.g., via Active Directory or GlobalProtect), the analyst must implement an Authentication Policy. This policy works in conjunction with Captive Portal. When traffic matches the criteria of an Authentication Policy, the firewall intercepts the request and redirects the user to a web-based login page.
Once the user successfully authenticates, their IP address is mapped to their username in the User-ID table, allowing subsequent traffic to pass through the standard Security Policy rules that require a specific user or group. This objective is critical for a Zero Trust architecture, as it ensures that "unknown" users on the network are challenged for credentials before being granted access to resources. This process provides the analyst with the necessary visibility and control to apply granular, identity-based security even in environments with unmanaged devices.