URL Anatomy

🎯 What You'll Learn

• All the parts of a URL
• What each component does
• How to construct URLs properly

📖 The Concept

A URL (Uniform Resource Locator) is like a complete address for finding anything on the web.

Breaking Down a URL

  https://user:pass@www.example.com:8080/path/to/page?search=hello&page=1#section2
  └─┬─┘  └───┬───┘ └──────┬──────┘└─┬─┘└─────┬─────┘└────────┬────────┘└───┬───┘
 scheme  userinfo       host      port     path            query        fragment

Component Details

Query String Format

Multiple parameters are joined with &:

?name=john&age=25&city=boston

Special characters must be encoded:

space → %20 or +
& → %26
= → %3D

🚀 Your Challenge

The server will quiz you on URL components! Answer correctly to get the flag.

curl http://challenge/quiz

Follow the instructions to construct the correct URL!

Good luck! 🍀

Directory Listing

🎯 What You'll Learn

• How web servers map URLs to files
• Directory listings and navigation
• Finding hidden files and folders

📖 The Concept

Web servers often serve files from a directory on disk. The URL path maps directly to the file system:

Server File System          URL Path
─────────────────          ──────────
/var/www/                  http://site.com/
├── index.html             http://site.com/index.html
├── about.html             http://site.com/about.html
├── images/                http://site.com/images/
│   ├── logo.png           http://site.com/images/logo.png
│   └── banner.jpg         http://site.com/images/banner.jpg
└── docs/                  http://site.com/docs/
    └── readme.txt         http://site.com/docs/readme.txt

Directory Listing

When you request a folder (not a file), the server might:

1. Show an index file (index.html) - most common
2. Show a directory listing - list of files
3. Return 403 Forbidden - access denied
4. Return 404 Not Found - pretend it doesn't exist

Exploring a Server

curl http://site.com/          # Root directory
curl http://site.com/images/   # Images folder
curl http://site.com/secret/   # Maybe something interesting?

🚀 Your Challenge

A file server is running with several directories. Explore the server to find the hidden flag!

Start by listing the root:

curl http://challenge/

Navigate through the directories to find the flag file!

Good luck! 🍀

Relative Paths

🎯 What You'll Learn

• Difference between absolute and relative paths
• How . and .. work
• Path traversal techniques

📖 The Concept

Absolute vs Relative Paths

Absolute Path: Full path from the root

/home/user/documents/file.txt
http://example.com/images/logo.png

Relative Path: Path from current location

./file.txt          (current directory)
../other/file.txt   (parent directory)
images/logo.png     (subdirectory)

Special Path Components

Path Traversal Examples

Starting at: /var/www/html/images/

./photo.jpg         → /var/www/html/images/photo.jpg
../index.html       → /var/www/html/index.html
../../config.txt    → /var/www/config.txt
../css/style.css    → /var/www/html/css/style.css

Web URL Path Traversal

Current URL: http://site.com/blog/posts/

./image.png         → http://site.com/blog/posts/image.png
../about            → http://site.com/blog/about
../../contact       → http://site.com/contact

🚀 Your Challenge

You're in /start/here/. Navigate using relative paths to find the flag!

curl http://challenge/start/here/

Use .. to move up directories and find flag.txt hidden elsewhere in the tree.

Good luck! 🍀

Index Files

🎯 What You'll Learn

• What index files are
• Why they exist
• Different index file names

📖 The Concept

When you request a directory (not a file), the server looks for a default file to show.

How It Works

Request: http://example.com/blog/

Server checks for (in order):
1. /blog/index.html    ← Most common
2. /blog/index.htm
3. /blog/index.php
4. /blog/default.html
5. Directory listing (if enabled)
6. 403 Forbidden

Common Index Files

Why Index Files Matter

1. Clean URLs: example.com/about/ instead of example.com/about/index.html
2. Security: Hides the actual file structure
3. Flexibility: Can change implementation without changing URLs

Explicit vs Implicit

# These often return the same content:
curl http://example.com/
curl http://example.com/index.html

# But not always! Server config matters.

🚀 Your Challenge

The server has multiple directories with different index files. Find the one that contains the flag!

Explore:

• / - What's the default index here?
• /blog/ - Check different index file names
• /admin/ - Might use a different default

curl http://challenge/
curl http://challenge/blog/
curl http://challenge/admin/

Try requesting specific index files to find the hidden flag!

Good luck! 🍀