Network (hardware) firewall

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Date:

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Quick Questions

Shade in the A or B circle for each question.

1. Where does a network (hardware) firewall sit?

A Between the local network and the internet

B Inside one laptop's apps folder

2. Which firewall protects many devices at once?

A A network firewall at the router

B A firewall app on one phone

3. Which of these can act as a network firewall?

A A USB drive plugged into one computer

B A home router with its firewall feature turned on

4. A network firewall filters which traffic?

A Both inbound and outbound traffic

B Only traffic that stays inside the LAN

5. A new tablet joins your home Wi-Fi. What happens with the router's firewall?

A The tablet is unprotected until it has its own firewall

B The tablet is protected without installing anything

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1network firewall		ADENY outbound port 23 for all devices
2inbound traffic		BInternet -> Firewall -> Switch -> Devices
3A network firewall can run on a router or a dedicated appliance placed between the LAN and the internet		CThe firewall is placed after the internet, so traffic reaches the network without being filtered. It must sit between the local network and the internet.
4One rule on a network firewall protects many devices at once, including outbound traffic		DData coming from the internet into the local network, which the firewall checks before letting it reach a device
5A network firewall only protects the one laptop it is installed on.		EA device or router feature between the local network and the internet that filters traffic for every device behind it
6Layout: Laptop -> Switch -> Internet -> Firewall		FThis describes software on a single device. A network firewall sits between the local network and the internet and filters traffic for every device behind it.

Definitions

network firewall

Fill in the Blanks

Complete each line of code by filling in the missing parts.

Internet -> ________ -> Switch -> PCs

RULE 1: ALLOW ________ TCP port 443

RULE 2: ____ inbound TCP port 23

FOR EACH device IN LAN ________.check(device.traffic) END FOR

Software firewall: protects 1 device Network firewall: protects ___ devices

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A firewall = inside(laptop)

B for each device in LAN:

C filter(device.traffic)

Question 2

A # block inbound Telnet

B rule 1: allow out port 443

C rule 2: allow in port 23

Question 3

A firewall = laptop.firewall

B devices = [laptop, phone, TV]

C protected = devices

Question 4

A direction = 'inbound'

B source = 'LAN'

C destination = 'LAN'

D fw.check(source, destination)

Question 5

A packet.src = '192.168.1.5'

B packet.dst = '8.8.8.8'

C direction = 'inbound'

D fw.check(packet, direction)

Answer Key

Network (hardware) firewall

Section A: Quick Questions

A — Between the local network and the internet

A — A network firewall at the router

B — A home router with its firewall feature turned on

A — Both inbound and outbound traffic

B — The tablet is protected without installing anything

Section B: Match the Pairs

network firewall → A device or router feature between the local network and the internet that filters traffic for every device behind it

inbound traffic → Data coming from the internet into the local network, which the firewall checks before letting it reach a device

A network firewall can run on a router or a dedicated appliance placed between the LAN and the internet → Internet -> Firewall -> Switch -> Devices

One rule on a network firewall protects many devices at once, including outbound traffic → DENY outbound port 23 for all devices

A network firewall only protects the one laptop it is installed on. → This describes software on a single device. A network firewall sits between the local network and the internet and filters traffic for every device behind it.

Layout: Laptop -> Switch -> Internet -> Firewall → The firewall is placed after the internet, so traffic reaches the network without being filtered. It must sit between the local network and the internet.

Section C: Definitions

network firewall — A device or router feature between a local network and the internet that filters inbound and outbound traffic for every device behind it, not just one.

Section D: Fill in the Blanks

Internet -> Firewall -> Switch -> PCs

RULE 1: ALLOW outbound TCP port 443

RULE 2: DENY inbound TCP port 23

FOR EACH device IN LAN
    firewall.check(device.traffic)
END FOR

Software firewall: protects 1 device
Network firewall: protects all devices

Section E: Spot the Error

A — A network firewall sits between the local network (LAN) and the internet (WAN). It is not placed inside one laptop. It should be firewall = between(LAN, WAN).

C — The comment says inbound Telnet (port 23) should be blocked, so the rule must deny it. It should be rule 2: deny in port 23.

A — A network firewall runs on the router or an appliance so it protects every device behind it. A firewall on the laptop would protect only the laptop. It should be firewall = router.firewall.

B — Inbound traffic comes from the internet and goes into the LAN. The source should be 'internet', not 'LAN'.

C — The packet starts at a private LAN address and is going to an internet address, so it is leaving the network. The direction should be 'outbound'.