Firewalls and packet filtering in Computer Networks - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a firewall in computer networks?

A firewall is a security system that controls incoming and outgoing network traffic based on set rules. It acts like a gatekeeper to protect a network from unauthorized access.

beginner

What does packet filtering mean?

Packet filtering is a method used by firewalls to check data packets and decide whether to allow or block them based on rules like source IP, destination IP, ports, or protocols.

intermediate

Name two types of firewalls.

Two common types of firewalls are: 1) Network-level firewalls that filter packets based on IP addresses and ports, and 2) Application-level firewalls that inspect the content of the traffic for specific applications.

intermediate

How does a stateful firewall differ from a stateless firewall?

A stateful firewall keeps track of active connections and makes decisions based on the state of the connection, while a stateless firewall treats each packet independently without context.

beginner

Why is packet filtering important for network security?

Packet filtering helps block harmful or unwanted traffic, preventing attacks and unauthorized access, which keeps the network safe and reliable.

What is the main role of a firewall?

A To create websites

B To speed up internet connection

C To store data securely

D To control network traffic based on security rules

A firewall controls network traffic by allowing or blocking data based on security rules.

Packet filtering checks packets based on which of the following?

A Source and destination IP addresses

B The color of the device

C The size of the screen

D The user's password

Packet filtering examines packet headers like source and destination IP addresses to decide if packets should pass.

Which type of firewall tracks the state of active connections?

A Physical firewall

B Stateless firewall

C Stateful firewall

D Cloud firewall

Stateful firewalls keep track of active connections to make smarter filtering decisions.

What happens if a packet does not meet the firewall rules?

A It is allowed through

B It is blocked or dropped

C It is sent twice

D It is ignored and logged

Packets that do not meet the rules are blocked to protect the network.

Which of these is NOT a function of a firewall?

A Encrypting all data automatically

B Preventing unauthorized access

C Monitoring network connections

D Filtering network traffic

Firewalls filter and monitor traffic but do not automatically encrypt all data.

Explain in your own words what a firewall does and why it is important for network security.

Think about how a firewall acts like a security guard for your network.

Describe how packet filtering works and what criteria it uses to allow or block data packets.

Imagine sorting mail based on sender and recipient addresses.