Test your Linux command line skills with 18 progressive Capture The Flag challenges. All flags follow the format CTF{some_text_here}.
Important
Please complete Phase 1 Guide before attempting these challenges. Do not share solutions publicly - focus on sharing your learning journey instead.
⏱️ Expected time: 3-4 hours to complete all challenges
| # | Challenge | Difficulty | Skills |
|---|---|---|---|
| 1 | The Hidden File | ⭐ | Hidden files, ls |
| 2 | The Secret File | ⭐ | File searching, find |
| 3 | The Largest Log | ⭐⭐ | File sizes, log navigation |
| 4 | The User Detective | ⭐⭐ | User management, UIDs |
| 5 | The Permissive File | ⭐⭐ | Permissions |
| 6 | The Hidden Service | ⭐⭐ | Networking, ports |
| 7 | The Encoded Secret | ⭐⭐ | Base64, encoding |
| 8 | SSH Key Authentication | ⭐⭐ | SSH configuration |
| 9 | DNS Troubleshooting | ⭐⭐ | DNS, /etc/resolv.conf |
| 10 | Remote Upload | ⭐⭐ | File transfer, SCP |
| 11 | Web Configuration | ⭐⭐ | Nginx, services |
| 12 | Network Traffic Analysis | ⭐⭐⭐ | Packet inspection, tcpdump |
| 13 | Cron Job Hunter | ⭐⭐ | Cron, scheduling |
| 14 | Process Environment | ⭐⭐⭐ | /proc, environment vars |
| 15 | Archive Archaeologist | ⭐⭐ | tar, gzip, archives |
| 16 | Symbolic Sleuth | ⭐⭐ | Symlinks, readlink |
| 17 | History Mystery | ⭐⭐ | Bash history |
| 18 | Disk Detective | ⭐⭐⭐ | Disk images, mounting |
Difficulty: ⭐ Beginner | ⭐⭐ Intermediate | ⭐⭐⭐ Advanced
Deploy your CTF lab using your preferred cloud provider:
| Provider | Cost for ~4 hours | Setup Guide |
|---|---|---|
| AWS | ~$0.01 (Free Tier eligible) | AWS Setup |
| Azure | ~$0.05 | Azure Setup |
| GCP | ~$0.03 | GCP Setup |
- Use
manpages to learn commands (e.g.,man find) - Combine commands with pipes (
|) to process output - Use
verify hint [num]when stuck on a challenge - Experiment freely—you can't break anything permanently
Want to help improve the CTF? See our Contributing Guide.
Please only submit issues with the lab infrastructure, not for help completing challenges—struggling is part of learning!