Task4

README.md

Task 4: Setup and Use a Firewall (Windows / Linux)

Objective: Configure and test basic firewall rules to allow or block traffic.
Tools: UFW (Uncomplicated Firewall) for Linux, Windows Firewall (PowerShell / netsh) for Windows.
Deliverables: Commands/configuration, test steps, and screenshots showing rules applied.

Repo structure

. ├─ README.md ├─ linux/ │ ├─ ufw_commands.sh │ ├─ ufw_rules_output.txt │ └─ screenshots/ │ ├─ ufw_status.png │ └─ ufw_test.png ├─ windows/ │ ├─ powershell_commands.ps1 │ ├─ netsh_rules_output.txt │ └─ screenshots/ │ ├─ wf_rules.png │ └─ wf_test.png ├─ interview_answers.md └─ LICENSE

How to use

Choose your OS directory (linux/ or windows/).
Run the commands (instructions in each file). For Linux, you will need sudo.
Save screenshots into the screenshots/ folder (names above) and commit them.
After completion, paste this repository link into the provided submission Google Form: https://forms.gle/8Gm83s53KbyXs3Ne9

Notes & safety

Do not expose remote services to the public Internet during testing.
If you open or block ports, revert the test rules at the end (commands provided).

📄 interview_answers.md

Interview Questions — Answers

1. What is a firewall?
A firewall is a network security device or software that monitors and controls incoming and outgoing network traffic based on an applied rule set. It enforces a security policy to allow, deny, or log traffic between networks or hosts.

2. Difference between stateful and stateless firewall?

Stateless firewall filters packets based solely on packet headers (IP, port, protocol) and treats each packet independently.
Stateful firewall keeps track of connection state (e.g., TCP handshake) and uses state information to make more informed decisions, allowing return traffic from established connections automatically.

3. What are inbound and outbound rules?

Inbound rules control traffic coming into a host or network.
Outbound rules control traffic leaving a host or network.

4. How does UFW simplify firewall management?
UFW (Uncomplicated Firewall) provides a simplified command-line interface for managing iptables rules. It abstracts complex iptables commands into simple allow/deny commands, supports named applications, and enables easy rule management for common tasks.

5. Why block port 23 (Telnet)?
Telnet transmits data (including credentials) in plaintext and lacks modern authentication and encryption. Blocking port 23 prevents insecure remote login and reduces risk of credential interception and unauthorized access.

6. What are common firewall mistakes?

Blocking management ports (e.g., SSH) without an alternate access method.
Leaving unnecessary ports open.
Misconfigured rules order (on devices where order matters).
Relying only on firewall without host hardening or monitoring.
Not logging or monitoring firewall events.

7. How does a firewall improve network security?
A firewall enforces network access policies, reduces attack surface by limiting services/ports, prevents unauthorized access, and can log suspicious traffic for further analysis.

8. What is NAT in firewalls?
NAT (Network Address Translation) translates private IP addresses to a public IP address for outgoing traffic. Firewalls often integrate NAT to allow internal hosts to access external networks while hiding internal addressing.

📄 COMMIT_INSTRUCTIONS.txt 1) Create directories: mkdir -p linux/screenshots windows/screenshots

2) Copy the provided files into the repo structure.

3) Take screenshots:

Run ‘sudo ufw status verbose’ and take a screenshot -> linux/screenshots/ufw_status.png
Run the test telnet/nc attempt and capture -> linux/screenshots/ufw_test.png
On Windows, use Windows Firewall GUI or PowerShell and capture -> windows/screenshots/wf_rules.png and wf_test.png

4) Commit: git add . git commit -m “Task 4: UFW and Windows Firewall configuration, commands, outputs, and interview answers” git push origin main

5) Submit the repo link on the Google Form: https://forms.gle/8Gm83s53KbyXs3Ne9

📄 linux/ufw_commands.sh #!/bin/bash

ufw_commands.sh

Run these commands on an Ubuntu/Debian-based Linux with sudo.

set -e

echo “1) Check UFW status and existing rules” sudo ufw status numbered

echo echo “2) Enable UFW if disabled (careful: this will enforce default rules)”

Uncomment next line only if you are ready to enable it.

sudo ufw enable

echo echo “3) Example: Block inbound Telnet (port 23)” sudo ufw deny 23/tcp comment ‘Block Telnet for Task 4’

echo echo “4) Example: Allow SSH (port 22) so you don’t lock yourself out” sudo ufw allow 22/tcp comment ‘Allow SSH’

echo echo “5) Check rules after changes” sudo ufw status verbose

echo echo “6) Test connectivity (on same host or remote host):” echo “ - From the same machine, try: nc -zv localhost 23” echo “ - From another host: nc -zv 23" echo echo "7) Remove the Telnet block rule (cleanup)" sudo ufw delete deny 23/tcp

echo echo “8) OPTIONAL: Reset UFW to default (removes all user rules)”

sudo ufw reset

echo “Done. Save screenshots of ‘sudo ufw status verbose’ as linux/screenshots/ufw_status.png”

📄 linux/ufw_rules_output.txt Status: active

To Action From – —— —- 22/tcp ALLOW Anywhere 23/tcp DENY Anywhere 22/tcp (v6) ALLOW Anywhere (v6) 23/tcp (v6) DENY Anywhere (v6)

📄 windows/powershell_commands.ps1

powershell_commands.ps1

Run as Administrator PowerShell

Write-Host “1) List current inbound rules (filtered example)” Get-NetFirewallRule -Direction Inbound | Select-Object -First 50 | Format-Table -AutoSize

Write-Host “2) Block inbound Telnet (port 23) - create a rule to block TCP port 23” New-NetFirewallRule -DisplayName “Block Telnet - Task4” -Direction Inbound -Action Block -Protocol TCP -LocalPort 23 -Description “Block Telnet for Task 4”

Write-Host “3) Allow SSH (port 22) if required (on Windows with SSH server installed)” New-NetFirewallRule -DisplayName “Allow SSH - Task4” -Direction Inbound -Action Allow -Protocol TCP -LocalPort 22 -Description “Allow SSH for remote admin”

Write-Host “4) View the rules you just created” Get-NetFirewallRule -DisplayName “Block Telnet - Task4” | Format-Table -AutoSize Get-NetFirewallRule -DisplayName “Allow SSH - Task4” | Format-Table -AutoSize

Write-Host “5) Test from another machine: telnet 23 (should fail)." Write-Host " Or use PowerShell Test-NetConnection -ComputerName -Port 23"

Write-Host “6) Remove the Block Telnet rule (cleanup)” Remove-NetFirewallRule -DisplayName “Block Telnet - Task4” Write-Host “Cleanup done.”

📄 windows/netsh_rules_output.txt

Example netsh advfirewall firewall show rule name=all output snippet:

Rule Name: Block Telnet - Task4 ———————————————————————- Enabled: Yes Direction: In Profiles: Domain,Private,Public Action: Block Protocol: TCP LocalPort: 23 Edge traversal: No