What is a primary use for a packet-filtering firewall?

A packet-filtering firewall is designed to control network traffic based on predetermined security rules. The primary use of such a firewall is to evaluate packets at the network layer and determine whether to allow or block them based on their source and destination IP addresses, port numbers, and the protocol being used.

Allowing outgoing traffic while blocking incoming traffic is particularly significant in protecting networks from unauthorized access and potential threats. This type of filtering helps ensure that only legitimate and established connections can send responses back to the originating request, thereby enhancing the overall security posture of the network.

While inspecting and analyzing traffic is a function more aligned with stateful firewalls or intrusion detection systems, and managing user access levels typically involves authentication and authorization measures that go beyond simple packet filtering, these are not the primary functions of a packet-filtering firewall. Therefore, allowing outgoing traffic while blocking incoming traffic stands as the main purpose of such a firewall type, focusing strictly on the fundamental aspects of traffic control based on packet attributes.