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Linux Firewall Lab: Configure ufw
Put a host firewall on a new web server: deny by default, allow SSH from one admin address and HTTPS from anywhere.
Last updated
Linux command line · Intermediate · About 12 minutes
The scenario
A new web server goes live tomorrow and has no host firewall. The security policy is short: incoming traffic is denied unless a rule allows it, SSH is allowed only from the administrators’ workstation at 10.0.0.8, and HTTPS is open to everyone. Plain HTTP stays closed.
Configure ufw to match, and remember the order: if you turn the firewall on before allowing SSH, a real server would cut off your own session.
A practice Ubuntu terminal that runs in your browser. It understands real commands, and nothing you type can break anything.
Your tasks
0 of 6 doneCheck whether the firewall is on. (not done yet)
Set the default policy for incoming traffic to deny. (not done yet)
Allow SSH (TCP port 22) from the admin workstation, 10.0.0.8, and from nowhere else. (not done yet)
Allow HTTPS (TCP port 443) from anywhere, and leave HTTP (port 80) closed. (not done yet)
Turn the firewall on. (not done yet)
List the rules with their numbers to confirm them. (not done yet)
student@web02Practice terminal · simulated
Practice terminal: real commands on a simulated Ubuntu server. Type help to see what it knows.
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About this lab
What you’ll practice, and where it’s tested
What you’ll practice
- Reading the firewall’s state with ufw status
- Setting a default-deny policy
- Allowing a port from one address
- Allowing a port from anywhere
- Enabling the firewall safely
Exams it helps with
- CompTIA Security+Domain: Security Operations
- CompTIA Linux+Domain: Security
- CompTIA Network+Domain: Network Security
- CompTIA Server+Domain: Security and Disaster Recovery
Free performance-based questions: Security+, Linux+, Network+, Server+
Walkthrough
One way to complete the lab, with the reason for each step. Try it yourself first.
Show the worked solution
- 1See where you’re starting from.
sudo ufw status - 2Deny incoming traffic unless a rule allows it.
sudo ufw default deny incoming - 3Allow SSH from the admin workstation only. Do this before enabling the firewall.
sudo ufw allow from 10.0.0.8 to any port 22 proto tcp - 4Allow HTTPS from anywhere.
sudo ufw allow 443/tcp - 5Turn the firewall on.
sudo ufw enable - 6Read the rules back.
sudo ufw status numbered
Guide
How to get the most from a lab
Type the commands yourself
Typing a command, getting it wrong and fixing it is what makes it stick. Use the hints when you’re stuck, not before.
Check the walkthrough afterwards
Every lab has a worked solution with the reason for each step. Read it even when you finished: there is often a shorter way.
Do it again from memory
Reset the lab a day later and do it without hints. If you can, you know it. If you can’t, you’ve found what to study.
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FAQs
Got Questions? We’ve Got Answers.
Find quick answers or contact our support team.
Is this a real Linux machine?
No. It’s a practice terminal that runs in your browser. It understands the real commands the lab needs, and many more, and it answers the way an Ubuntu server would. It isn’t a full operating system: nothing is installed, and nothing you type can break anything.
Which commands does the practice terminal understand?
The everyday ones: ls, cd, cat, grep, awk, sed, sort, uniq, find, chmod, chown, useradd, usermod, passwd, systemctl, journalctl, ip, ping, dig, ss and ufw, with pipes, redirects and sudo. Type help in the terminal for the full list. Text editors and package installs aren’t included.
Which exams does this lab help with?
It practices skills from CompTIA Security+ (Security Operations), CompTIA Linux+ (Security), CompTIA Network+ (Network Security) and CompTIA Server+ (Security and Disaster Recovery).
Do I need an account?
No. The labs run in your browser and nothing is saved. Sign up only if you want OpenpassAI’s full labs and progress tracking.
