Firewall rules concept in GCP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to specify the direction of the firewall rule.

GCP

resource "google_compute_firewall" "default" {
  name    = "allow-internal"
  network = "default"
  direction = "[1]"
}

Drag options to blanks, or click blank then click option'

AOUTBOUND

BEGRESS

CINBOUND

DINGRESS

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'INBOUND' or 'OUTBOUND' which are not valid values in GCP firewall rules.

The direction field in a firewall rule specifies if the rule applies to incoming (INGRESS) or outgoing (EGRESS) traffic.

2fill in blank

medium

Complete the code to allow TCP traffic on port 80.

GCP

resource "google_compute_firewall" "http" {
  name    = "allow-http"
  network = "default"
  allow {
    protocol = "[1]"
    ports    = ["80"]
  }
}

Drag options to blanks, or click blank then click option'

Ahttp

Budp

Ctcp

Dicmp

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'http' as a protocol which is not valid in firewall rules.

The protocol field specifies the network protocol. For web traffic on port 80, TCP is used.

3fill in blank

hard

Fix the error in the source range specification to allow traffic from any IP.

GCP

resource "google_compute_firewall" "allow-all" {
  name    = "allow-all"
  network = "default"
  allow {
    protocol = "tcp"
    ports    = ["0-65535"]
  }
  source_ranges = ["[1]"]
}

Drag options to blanks, or click blank then click option'

Aany

B0.0.0.0/0

C0.0.0.0

D255.255.255.255/32

Attempts:

3 left

💡 Hint

Common Mistakes

Using '0.0.0.0' without CIDR suffix which is invalid.

Using 'any' which is not accepted.

The source_ranges field requires a CIDR notation. To allow all IPs, use '0.0.0.0/0'.

4fill in blank

hard

Fill both blanks to create a firewall rule that denies all egress UDP traffic.

GCP

resource "google_compute_firewall" "deny-udp-egress" {
  name    = "deny-udp-egress"
  network = "default"
  direction = "[1]"
  deny {
    protocol = "[2]"
  }
}

Drag options to blanks, or click blank then click option'

AEGRESS

BINGRESS

Cudp

Dtcp

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing INGRESS and EGRESS directions.

Using TCP instead of UDP.

To block outgoing UDP traffic, set direction to 'EGRESS' and protocol to 'udp' in the deny block.

5fill in blank

hard

Fill all three blanks to create a firewall rule allowing SSH from a specific IP range.

GCP

resource "google_compute_firewall" "allow-ssh" {
  name    = "allow-ssh"
  network = "default"
  direction = "[1]"
  allow {
    protocol = "[2]"
    ports    = ["[3]"]
  }
  source_ranges = ["192.168.1.0/24"]
}

Drag options to blanks, or click blank then click option'

AINGRESS

Btcp

C22

DEGRESS

Attempts:

3 left

💡 Hint

Common Mistakes

Setting direction to EGRESS instead of INGRESS.

Using wrong protocol or port.

SSH uses TCP protocol on port 22 and is usually allowed for incoming (INGRESS) traffic.

Practice

1. What is the main purpose of a firewall rule in Google Cloud Platform?

easy

A. To control network traffic by allowing or blocking it based on defined conditions

B. To store data securely in the cloud

C. To monitor user activity logs

D. To automatically backup virtual machines

Solution

1. Step 1: Understand what firewall rules do

   Firewall rules are designed to control network traffic by specifying which traffic is allowed or denied.

2. Step 2: Identify the correct function in GCP context

   In GCP, firewall rules specifically allow or block traffic based on protocols, ports, and IP ranges.

3. Final Answer:

   To control network traffic by allowing or blocking it based on defined conditions -> Option A

4. Quick Check:

   Firewall rules control traffic = B [OK]

Hint: Firewall rules manage traffic access, not data or backups [OK]

Common Mistakes:

• Confusing firewall rules with data storage
• Thinking firewall rules monitor logs
• Assuming firewall rules handle backups

2. Which of the following is the correct way to specify a firewall rule to allow TCP traffic on port 80 from any IP address in GCP?

easy

A. protocol: 'tcp', ports: ['80'], sourceRanges: ['0.0.0.0/0']

B. protocol: 'udp', ports: ['80'], sourceRanges: ['0.0.0.0/0']

C. protocol: 'tcp', ports: ['22'], sourceRanges: ['0.0.0.0/0']

D. protocol: 'icmp', ports: ['80'], sourceRanges: ['0.0.0.0/0']

Solution

1. Step 1: Identify the protocol and port for HTTP traffic

   HTTP uses TCP protocol on port 80.

2. Step 2: Check the source IP range

   '0.0.0.0/0' means any IP address, which matches the requirement.

3. Final Answer:

   protocol: 'tcp', ports: ['80'], sourceRanges: ['0.0.0.0/0'] -> Option A

4. Quick Check:

   TCP port 80 from any IP = A [OK]

Hint: HTTP uses TCP port 80; source 0.0.0.0/0 means all IPs [OK]

Common Mistakes:

• Using UDP instead of TCP for HTTP
• Specifying wrong port like 22
• Using ICMP protocol for port-based rules

3. Given this firewall rule in GCP:

{"direction": "INGRESS", "allowed": [{"IPProtocol": "tcp", "ports": ["22"]}], "sourceRanges": ["192.168.1.0/24"]}

Which traffic will be allowed?

medium

A. UDP traffic on port 22 from IP 192.168.1.15

B. TCP traffic on port 22 from IP 192.168.1.15

C. TCP traffic on port 80 from IP 192.168.1.15

D. TCP traffic on port 22 from IP 10.0.0.5

Solution

1. Step 1: Analyze the allowed protocol and port

   The rule allows TCP protocol on port 22 only.

2. Step 2: Check the source IP range

   Only IPs in 192.168.1.0/24 are allowed, so 192.168.1.15 is included, but 10.0.0.5 is not.

3. Final Answer:

   TCP traffic on port 22 from IP 192.168.1.15 -> Option B

4. Quick Check:

   TCP port 22 from 192.168.1.x allowed = C [OK]

Hint: Match protocol, port, and source IP range exactly [OK]

Common Mistakes:

• Allowing wrong port like 80
• Allowing UDP instead of TCP
• Ignoring source IP range restrictions

4. You created a firewall rule to allow TCP traffic on port 443 from IP range 10.0.0.0/16, but your VM instances cannot receive HTTPS traffic. What is the most likely mistake?

medium

A. The protocol should be UDP instead of TCP

B. The port number should be 80 instead of 443

C. The sourceRanges should be 0.0.0.0/0 to allow all traffic

D. The firewall rule direction is set to EGRESS instead of INGRESS

Solution

1. Step 1: Understand traffic direction for incoming HTTPS

   HTTPS traffic comes into the VM, so firewall rule must be INGRESS.

2. Step 2: Check the rule direction

   If the rule is EGRESS, it controls outgoing traffic, so incoming HTTPS is blocked.

3. Final Answer:

   The firewall rule direction is set to EGRESS instead of INGRESS -> Option D

4. Quick Check:

   Ingress needed for incoming traffic = D [OK]

Hint: Ingress rules allow incoming traffic; check direction [OK]

Common Mistakes:

• Confusing ingress and egress directions
• Changing port from 443 to 80 incorrectly
• Opening sourceRanges too wide unnecessarily

5. You want to create a firewall rule that allows SSH (TCP port 22) access only from your office IP 203.0.113.5 and blocks all other SSH traffic. Which configuration achieves this securely?

hard

A. Allow TCP port 22 from 203.0.113.5 and deny TCP port 22 from 0.0.0.0/0

B. Allow TCP port 22 from 0.0.0.0/0 and deny TCP port 22 from 203.0.113.5

C. Allow TCP port 22 from 203.0.113.5 only, no other rules needed

D. Deny all TCP traffic and allow UDP port 22 from 203.0.113.5

Solution

1. Step 1: Understand default firewall behavior

   By default, GCP denies all traffic unless explicitly allowed.

2. Step 2: Allow only SSH from office IP

   Allowing TCP port 22 from 203.0.113.5 only permits SSH from that IP; no deny rule needed.

3. Step 3: Avoid conflicting rules

   Adding deny rules can cause conflicts; simplest is to allow only the trusted IP.

4. Final Answer:

   Allow TCP port 22 from 203.0.113.5 only, no other rules needed -> Option C

5. Quick Check:

   Allow trusted IP only; default deny others = A [OK]

Hint: Allow trusted IP only; default deny blocks others [OK]

Common Mistakes:

• Adding unnecessary deny rules causing conflicts
• Allowing all IPs then trying to deny one
• Using wrong protocol or port