Service and port management in Cybersecurity - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to display the port number used by the HTTP service.

Cybersecurity

print('The HTTP service uses port [1]')

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

A21

B25

C443

D80

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing HTTP port with FTP (21) or HTTPS (443).

HTTP typically uses port 80 for communication.

2fill in blank

medium

Complete the command to check which service is listening on port {{BLANK_1}}.

Cybersecurity

netstat -an | grep [1]

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

A22

B53

C80

D110

Attempts:

3 left

💡 Hint

Common Mistakes

Using port 80 which is for HTTP, not SSH.

Port 22 is commonly used by SSH service.

3fill in blank

hard

Fix the error in the command to stop the service running on port {{BLANK_1}}.

Cybersecurity

sudo fuser -k [1]/tcp

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

A21

B22

C80

D25

Attempts:

3 left

💡 Hint

Common Mistakes

Using port 22 which is for SSH, not HTTP.

Port 80 is used by HTTP service, which can be stopped using this command.

4fill in blank

hard

Fill both blanks to create a dictionary mapping services to their default ports.

Cybersecurity

services = {'HTTP': [1], 'FTP': [2]

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

A80

B21

C22

D443

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing FTP port with SSH port 22.

HTTP uses port 80 and FTP uses port 21 by default.

5fill in blank

hard

Fill all three blanks to filter services running on ports greater than 1024.

Cybersecurity

filtered_services = {service: port for service, port in services.items() if port [1] 1024 [2] service != '[3]'}

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

A>

Band

C<

DHTTP

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' for port comparison.

Not excluding HTTP service correctly.

This code filters services with ports greater than 1024 and excludes HTTP.

Practice

1. What is the main purpose of managing services and ports on a computer system?

easy

A. To control which services are accessible and improve security

B. To increase the speed of the internet connection

C. To install new software automatically

D. To backup all files on the system

Solution

1. Step 1: Understand service and port roles

   Services use ports to communicate over networks, so managing them controls access.

2. Step 2: Identify the security benefit

   Closing unused ports prevents unauthorized access, improving system security.

3. Final Answer:

   To control which services are accessible and improve security -> Option A

4. Quick Check:

   Service and port management = Control access [OK]

Hint: Managing ports controls access to services for security [OK]

Common Mistakes:

• Confusing port management with internet speed
• Thinking it installs software
• Assuming it backs up files

2. Which of the following is the correct way to specify a port number when configuring a service?

easy

A. Using letters instead of numbers

B. Using any number above 70000

C. Using negative numbers

D. Using a number between 0 and 65535

Solution

1. Step 1: Recall valid port number range

   Ports are numbered from 0 to 65535 according to networking standards.

2. Step 2: Eliminate invalid options

   Numbers above 65535, negative numbers, or letters are invalid for ports.

3. Final Answer:

   Using a number between 0 and 65535 -> Option D

4. Quick Check:

   Port numbers range 0-65535 [OK]

Hint: Ports must be 0-65535, no letters or negatives [OK]

Common Mistakes:

• Choosing numbers above 65535
• Using negative numbers
• Using letters as ports

3. Consider a server running a web service on port 80 and an SSH service on port 22. If the firewall blocks port 22 but allows port 80, what will happen?

medium

A. Users can access the web service but cannot connect via SSH

B. Users can connect via SSH but cannot access the web service

C. Both web and SSH services will be accessible

D. Neither web nor SSH services will be accessible

Solution

1. Step 1: Identify allowed and blocked ports

   Port 80 (web) is allowed; port 22 (SSH) is blocked by the firewall.

2. Step 2: Determine service accessibility

   Web service on port 80 will be accessible; SSH on port 22 will be blocked.

3. Final Answer:

   Users can access the web service but cannot connect via SSH -> Option A

4. Quick Check:

   Firewall blocks port 22, allows 80 = Web yes, SSH no [OK]

Hint: Blocked port means service on it is inaccessible [OK]

Common Mistakes:

• Assuming blocked port still allows access
• Confusing port numbers with services
• Thinking all services are blocked

4. A system administrator tries to start a service on port 21 but gets an error. The port is already in use by another service. What is the best way to fix this?

medium

A. Restart the computer without checking the port

B. Ignore the error and run both services on port 21

C. Change the new service to use a different free port

D. Uninstall the operating system

Solution

1. Step 1: Understand port conflict

   Two services cannot use the same port simultaneously; this causes errors.

2. Step 2: Choose a solution to avoid conflict

   Changing the new service to a free port resolves the conflict safely.

3. Final Answer:

   Change the new service to use a different free port -> Option C

4. Quick Check:

   Port conflict fixed by using different port [OK]

Hint: Use a free port to avoid conflicts [OK]

Common Mistakes:

• Restarting without fixing port conflict
• Trying to run two services on same port
• Taking extreme actions like uninstalling OS

5. You want to secure a server by closing all unused ports but keep services on ports 22 (SSH), 80 (HTTP), and 443 (HTTPS) open. Which approach is best?

hard

A. Disable all services including SSH, HTTP, and HTTPS

B. Configure the firewall to block all ports except 22, 80, and 443

C. Open all ports to avoid blocking any service

D. Only block port 80 and 443, keep others open

Solution

1. Step 1: Identify required open ports

   Services on ports 22, 80, and 443 must remain accessible for SSH and web traffic.

2. Step 2: Apply firewall rules to block unused ports

   Blocking all other ports except these three limits exposure and secures the server.

3. Final Answer:

   Configure the firewall to block all ports except 22, 80, and 443 -> Option B

4. Quick Check:

   Block unused ports, keep needed open = Secure server [OK]

Hint: Block all except needed ports for best security [OK]

Common Mistakes:

• Disabling needed services
• Opening all ports reduces security
• Blocking needed ports breaks services