Download Text

🎯 What You'll Learn

• Downloading text content from servers
• Understanding Content-Type headers
• Reading server responses

📖 The Concept

The simplest form of downloading is retrieving text. When you curl a URL, you're downloading content!

How Downloads Work

1. Client sends GET request
2. Server sends headers (metadata about the content)
3. Server sends body (the actual content)
4. Client receives and displays/saves it

Content-Type Header

The server tells you what kind of content it's sending:

Content-Type: text/plain          ← Plain text
Content-Type: text/html           ← HTML page
Content-Type: application/json    ← JSON data
Content-Type: text/csv            ← CSV data

Basic Download with curl

curl http://example.com/file.txt      # Display content
curl -s http://example.com/file.txt   # Silent mode (no progress)

Checking Headers Only

curl -I http://example.com/file.txt   # HEAD request - headers only
curl -i http://example.com/file.txt   # Include headers with content

🚀 Your Challenge

Download a text file from the server. The file contains encoded data - decode it to find the flag!

curl http://challenge/secret.txt

The content is base64 encoded. Decode it with:

curl http://challenge/secret.txt | base64 -d

Good luck! 🍀

Download Binary

🎯 What You'll Learn

• Downloading binary files (images, archives)
• Binary vs text content
• Using curl for binary downloads

📖 The Concept

Not all files are text! Binary files include:

• Images (PNG, JPG, GIF)
• Archives (ZIP, TAR, GZ)
• Executables (EXE, binary programs)
• Documents (PDF, DOCX)

Binary Content-Types

Content-Type: image/png
Content-Type: image/jpeg
Content-Type: application/zip
Content-Type: application/octet-stream  ← Generic binary

Downloading Binary with curl

# Save to file (important for binary!)
curl http://example.com/image.png -o image.png

# Using output redirection
curl http://example.com/archive.zip > archive.zip

Inspecting Binary Files

file image.png           # Identify file type
hexdump -C file.bin      # View hex content
strings file.bin         # Extract text from binary

🚀 Your Challenge

Download a PNG image from the server. The flag is hidden in the image metadata!

# Download the image
curl http://challenge/secret.png -o secret.png

# Check the file
file secret.png

# Extract strings (text) from the binary
strings secret.png | grep flag

Good luck! 🍀

Save to File

🎯 What You'll Learn

• Saving downloads to files
• Using curl output options
• wget as an alternative

📖 The Concept

By default, curl prints content to your terminal. For files, you want to save to disk!

curl Output Options

# -o: Save to specific filename
curl http://example.com/data.json -o mydata.json

# -O: Save with original filename from URL
curl -O http://example.com/report.pdf

# Redirect to file
curl http://example.com/page > page.html

wget Alternative

# wget saves to file by default
wget http://example.com/file.zip

# Specify output name
wget http://example.com/file.zip -O custom-name.zip

# Quiet mode
wget -q http://example.com/file.zip

curl vs wget

🚀 Your Challenge

The server generates a unique file each time. Download it, save it, and read its contents!

# Step 1: Save the file
curl http://challenge/generate -o flag.txt

# Step 2: Read the saved file
cat flag.txt

⚠️ The content only displays correctly when saved to a file (not printed to terminal)!

Good luck! 🍀

Follow Redirects

🎯 What You'll Learn

• HTTP redirects (301, 302, etc.)
• Following redirect chains
• Using curl -L option

📖 The Concept

Servers can tell clients "the thing you want is somewhere else" using redirects.

Redirect Status Codes

How Redirects Work

Client: GET /old-page
Server: 301 Moved Permanently
        Location: /new-page

Client: GET /new-page  (if following redirects)
Server: 200 OK + content

curl and Redirects

# Default: curl does NOT follow redirects
curl http://example.com/old    # Shows redirect response

# -L: Follow redirects automatically
curl -L http://example.com/old  # Gets final content

# -I: See redirect headers
curl -I http://example.com/old

Maximum Redirects

curl -L --max-redirs 5 http://example.com/  # Max 5 redirects

🚀 Your Challenge

The flag is hidden behind multiple redirects! Follow them all to find it.

# This shows only the redirect response
curl http://challenge/start

# This follows all redirects to the end
curl -L http://challenge/start

Good luck! 🍀