3.2 Network Firewall Concepts

Question 1

What is the fundamental purpose of a firewall?

Answer 1

To control the flow of traffic between two points.

Question 2

Where are firewalls commonly deployed?

Answer 2

In homes, offices, and often built into operating systems.

Question 3

What additional security functions can firewalls provide?

Answer 3

• Antivirus protection
• Anti-malware protection
• Content filtering (e.g., parental controls)

Question 4

What is the key difference between a traditional network-based firewall and a next-generation firewall (NGFW)?

Answer 4

Traditional firewalls control traffic based on OSI Layer 4, while NGFWs manage traffic based on OSI Layer 7.

Question 5

How can firewalls function as Layer 3 devices?

Answer 5

They control internal and external traffic flows and provide services like Network Address Translation (NAT).

Question 6

Define a Unified Threat Management (UTM) device.

Answer 6

An older firewall that includes multiple security and network features bundled within a single appliance.

Question 7

List two common features of UTM devices.

Answer 7

• URL filtering
• Content inspection

Question 8

What is the primary performance challenge associated with UTM devices?

Answer 8

Having many separate capabilities in one appliance often leads to performance drawbacks.

Question 9

How does an NGFW make forwarding decisions differently from a Layer 4 firewall?

Answer 9

NGFWs examine application layer content for decisions, regardless of port number.

Question 10

Provide an example of a decision an NGFW could make.

Answer 10

Allow users to view Twitter but restrict posting to Twitter.

Question 11

What is the primary function of a Web Application Firewall (WAF)?

Answer 11

To analyze input into web-based applications and protect against malicious input.

Question 12

Why might a WAF be used alongside an NGFW?

Answer 12

They focus on different traffic aspects and make different forwarding decisions.

Question 13

Give an example of a specific type of attack a WAF is designed to block.

Answer 13

SQL injection.

Question 14

What does the term ‘network-based firewall’ refer to?

Answer 14

A firewall that controls network traffic, traditionally using OSI Layer 4.

Question 15

What is the OSI Layer 4?

Answer 15

The Transport Layer, used by traditional firewalls to control traffic based on port numbers.

Question 16

What is the OSI Layer 7?

Answer 16

The Application Layer, used by NGFWs to manage traffic based on the application.

Question 17

Define Deep Packet Inspection (DPI).

Answer 17

A function of NGFWs that examines all traffic and decodes packets to understand contents.

Question 18

What is a Web Security Gateway?

Answer 18

An alternate term for a Unified Threat Management (UTM) device.

Question 19

What is a VPN Concentrator?

Answer 19

A device that acts as an endpoint for multiple VPN connections.

Question 20

What is an Intrusion Prevention System (IPS)?

Answer 20

A security feature designed to block malicious software or traffic flows.

Question 21

What is Network Address Translation (NAT)?

Answer 21

A routing protocol functionality provided by Layer 3 firewalls.

Question 22

What is a Bandwidth Shaper?

Answer 22

A capability that allows for Quality of Service (QoS) across applications.

Question 23

What is PCI DSS?

Answer 23

Payment Card Industry Data Security Standard, which mandates WAF use for credit card applications.