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Flip to reveal answersWhat does a firewall do?
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All 5 Flashcards — Firewalls
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Question
What does a firewall do?
Answer
Sits where the network meets the outside world and inspects every packet crossing it, allowing or dropping each one by rule — on outgoing traffic as well as incoming.
Question
What is the difference between a whitelist and a blacklist?
Answer
A whitelist allows only what is listed and blocks everything else: safe by default but restrictive. A blacklist blocks only what is listed: convenient, but anything not yet known about gets through, so it is always a step behind.
Question
Why do outgoing firewall rules matter?
Answer
They stop an already-infected machine sending stolen data out or contacting whoever controls it. Most answers mention only incoming traffic, so this is a reliable extra mark.
Question
Name three things a firewall cannot protect against.
Answer
Traffic that never crosses it, such as malware on a USB stick or one internal machine infecting another; the contents of encrypted connections, which it cannot read; and attacks delivered over ports the rules legitimately allow.
Question
How does NAT contribute to security, and what are its limits?
Answer
Internal machines have private addresses that are not routable, so nothing outside can address them directly — only reply to conversations they start. But NAT does nothing about outgoing traffic, what an allowed connection carries, or anything inside the network.
Read the notes
Full study notes for Firewalls
Topic 2.4 hub
Network security
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Computer Science exam skills
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