linux-ctfs - A collection of Linux CTFs to practice your CLI sk

项目说明

Phase 1: Linux Command Line CTF Challenge

Test your Linux command line skills with 18 progressi The Flag challenges.

> [!IMPORTANT]
> Please complete Phase 1 Guide before attempting these challenges. Do not share solutions publicly - focus on sharing your learning journey instead.

Get Started

You'll need: a cloud account (AWS, Azure, or GCP), Terraform, your provider's CLI, and about 3-4 hours.

1. Fork this repository to your GitHub account. Completion checks that you have a fork.
2. Deploy the lab with your provider's guide:

| Provider | Cost for ~4 hours | Guide |
|----------|-------------------|-------|
| AWS | ~$0.01 (Free Tier eligible) | AWS Guide |
| Azure | ~$0.05 | Azure Guide |
| GCP | ~$0.03 | GCP Guide |

3. Play by connecting over SSH and solving challenges with the Playing the Lab guide. It covers the command and exporting your completion token.
4. Clean up with terraform destroy when you're done, after saving your token, so you aren't billed for a VM you' with.

Running into problems? See TROUBLESHOOTING.md.

Challenges

> ⏱️ Expected time: 3-4 hours to complete all challenges

| # | Challenge | Description | Difficulty | Skills |
|---|-----------|-------------|------------|--------|
| 1 | The Hidden File | Find and read a hidden file in ctf_challenges | ⭐ | Hidden files, directory listing |
| 2 | The Secret File | Locate a regular file (not a directory) with "secret" in its name under your home directory | ⭐ | File searching |
| 3 | The Odd Log Entry | Thousands of failed logins hide a single successful one in a log under /var/log | ⭐⭐ | Log analysis, text filtering |
| 4 | The User Detective | Another user's account record carries a flag | ⭐⭐ | Users, account records |
| 5 | The Permissive File | Find a suspicious file with wide-open permissions under /opt, then follow where it leads | ⭐⭐ | Permissions, file ownership |
| 6 | The Hidden Service | Something is listening on port 8080. Connect to it | ⭐⭐ | Networking, ports |
| 7 | The Encoded Secret | Find and decode an encoded flag in ctf_challenges | ⭐⭐ | Encoding, decoding |
| 8 | SSH Key Authentication | Set up SSH key authentication to log in as the key-only vault user | ⭐⭐⭐ | SSH key authentication, users |
| 9 | DNS Inspection | Find the lab's custom search domain and resolve a host inside it | ⭐⭐ | DNS, name resolution |
| 10 | Remote Upload | From your own computer, upload a new file into ~/ctf_challenges on the VM to trigger the flag. It is broadcast to your open terminals | ⭐⭐ | File transfer |
| 11 | Web Configuration | nginx should serve the site on port 80 but is misconfigured. Find and fix it | ⭐⭐ | Web servers, services, config debugging |
| 12 | Network Traffic Analysis | Someone is sending secret messages via ping packets on the loopback interface (needs sudo) | ⭐⭐⭐ | Packet inspection |
| 13 | Cron Job Hunter | A scheduled job handles a secret. Find out what it runs and inspect the result | ⭐⭐ | Cron, scheduling |
| 14 | Process En | A running process has a secret in its en. Extract it | ⭐⭐⭐ | Processes, en |
| 15 | Archi | A flag is buried inside nested archives. Dig it out | ⭐⭐ | Archives, compression |
| 16 | Symbolic Sleuth | Start at follow_me in ~/ctf_challenges and follow the trail of symbolic links. The flag is where the trail ends | ⭐⭐ | Symbolic links |
| 17 | History Mystery | Someone typed a secret into their command line. Find it. Not every secret is the real one | ⭐⭐ | Shell history, text search |
| 18 | Disk Detective | A flag is hidden in filesystem metadata. Inspect the disk image | ⭐⭐⭐ | Disk images, filesystem metadata |

Difficulty: ⭐ Beginner | ⭐⭐ Intermediate | ⭐⭐⭐ Ad

There are 18 challenges. progress reports /19 because it also counts the practice flag (challenge 0) that checks works.

About Your Completion Certificate

The certificate and token from export work on the honor system. They record that you finished the lab, but they can't prove it. You control the VM and have root on it, and the token's signing key is in this public repository, so anyone determined to fake a token can.

That's a deliberate choice. The lab exists to build your skills, and a token you didn't earn gets you nothing. Anyone re your work should treat the certificate as your own statement, not as proof.

Contributing

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!

License

MIT License

项目信息

开发语言：Python

Star 数：316

技术要点

该项目属于CTF思路方向的开源资源，代码结构清晰，适合安全研究人员学习参考。项目围绕A collection of Linux CTFs to practice your CLI skills展开，提供了可运行的实现，对理解相关安全机制、工具原理与攻防技术具有较高的研究价值。

从技术实现角度看，此类项目的核心在于对底层原理的深入理解与工程化落地。开发者在研究过程中可以结合官方文档与社区讨论，梳理项目的初始化流程、核心模块职责与数据流转，逐步掌握其中的技术细节与设计思路。

使用与学习建议

1. 下载源码压缩包，解压到本地环境。

2. 根据项目类型准备对应的运行环境与依赖。

3. 按照 README 中的步骤完成配置与部署。

4. 在隔离的测试环境中运行验证，避免影响生产系统。

免责声明

本资源来源于开源社区，仅供安全研究、技术学习与合法授权范围内的攻防演练使用，请勿用于任何非法或侵害他人权益的用途。使用本项目产生的一切后果由使用者自行承担。