How does the AOS firewall determine which rules to apply to a specific client's traffic?

In an AOS-8 architecture, the Mobility Controller (MC) includes a stateful firewall that enforces policies on client traffic. The firewall uses user roles to apply policies, allowing granular control over traffic based on the client’s identity and context.

User Roles: In AOS-8, each client is assigned a user role after authentication (e.g., via 802.1X, MAC authentication, or captive portal). The user role contains firewall policies (rules) that define what traffic is allowed or denied for clients in that role. For example, a "guest" role might allow only HTTP/HTTPS traffic, while an "employee" role might allow broader access.

Option A, "The firewall applies the rules in policies associated with the client's user role," is correct. The AOS firewall evaluates traffic based on the user role assigned to the client. Each role has a set of policies (rules) that are applied in order, and the first matching rule determines the action (permit or deny). For example, if a client is in the "employee" role, the firewall applies the rules defined in the "employee" role’s policy.

Option B, "The firewall applies every rule that includes the client's IP address as the source," is incorrect. The firewall does not apply rules based solely on the client’s IP address; it uses the user role. Rules within a role may include IP addresses, but the role determines which rules are evaluated.

Option C, "The firewall applies the rules in policies associated with the client's WLAN," is incorrect. While the WLAN configuration defines the initial role for clients (e.g., the default 802.1X role), the firewall applies rules based on the client’s current user role, which may change after authentication (e.g., via a RADIUS VSA like Aruba-User-Role).

Option D, "The firewall applies every rule that includes the client's IP address as the source or destination," is incorrect for the same reason as Option B. The firewall uses the user role to determine which rules to apply, not just the client’s IP address.

The HPE Aruba Networking AOS-8 8.11 User Guide states:

"The AOS firewall on the Mobility Controller applies rules based on the user role assigned to a client. Each user role contains a set of firewall policies that define the allowed or denied traffic for clients in that role. For example, a policy in the ‘employee’ role might include a rule like ipv4 user any http permit to allow HTTP traffic. The firewall evaluates the rules in the client’s role in order, and the first matching rule determines the action for the traffic." (Page 325, Firewall Policies Section)

Additionally, the HPE Aruba Networking Security Guide notes:

"User roles in AOS-8 provide a powerful mechanism for firewall policy enforcement. The firewall determines which rules to apply to a client’s traffic by looking at the policies associated with the client’s user role, which is assigned during authentication or via a RADIUS VSA like Aruba-User-Role." (Page 50, Role-Based Access Control Section)