Which type of access control is used on a router or firewall to limit network activity?

Mandatory Access Control (MAC) uses security labels and classifications assigned by a central authority, not packet-filtering rules on network devices.

Discretionary Access Control (DAC) allows resource owners to set permissions on their own objects, which is a file/object model not applied to network traffic filtering.

Rule-based access control evaluates traffic against an ordered set of administrator-defined rules, which is exactly how ACLs on routers and firewalls operate - each packet is matched against rules specifying source/destination IP, port, and protocol to permit or deny passage. This is the standard mechanism for filtering network activity at the perimeter.

Role-Based Access Control (RBAC) assigns permissions based on a user's organizational role, which governs user account privileges rather than network packet flow.