Question 1

What is a firewall and how does it work?

Accepted Answer

A firewall is a network security device that monitors and filters incoming and outgoing traffic based on predefined rules. It acts as a barrier between trusted internal networks and untrusted external networks. Firewalls can operate at different layers — packet filtering (Layer 3/4), stateful inspection (tracking connection state), and application-layer (Layer 7) filtering that inspects actual content.

Question 2

What is the difference between allow and deny firewall rules?

Accepted Answer

Allow rules permit traffic that matches specific criteria (source IP, destination port, protocol) to pass through. Deny rules block matching traffic. Most firewalls use a default-deny policy — all traffic is blocked unless explicitly allowed. Rules are evaluated in order, and the first matching rule determines the action. This approach follows the principle of least privilege.

Firewall Rules

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