Firewalls and ACLs

Firewalls and ACLs are the toll booths of the digital highway. Stateless firewalls inspect each packet in isolation—like guards checking every individual car’s license plate, where stateful firewalls keep track of entire journeys, allowing return traffic only if the outbound trip was legitimate. In practice you want a “deny by default” stance, just like closing all lanes except the explicitly opened toll booths, and you must regularly audit the rule base to remove stale or overly permissive entries that leave unintended gaps in your defenses.