How the cupp.py download_wordlist Function Fetches Files from FTP Repositories

The download_wordlist function retrieves FTP-hosted wordlists by constructing URLs from the dicturl configuration entry and delegating the transfer to urllib.request.urlopen, which transparently handles both HTTP and FTP schemes without requiring protocol-specific code.

The cupp.py password profiling tool includes an automated wordlist downloader that can retrieve dictionary files from FTP repositories. When users invoke the -l command-line flag, the download_wordlist function orchestrates a fetch sequence that relies on Python's standard library to handle FTP transfers transparently, requiring no external FTP libraries or manual authentication handling.

The FTP Download Architecture

The download process relies on a three-tier architecture that separates user interaction, URL construction, and the actual network transfer.

Configuration and URL Construction

When a user runs python3 cupp.py -l, the download_wordlist function (implemented around lines 998-1002 in cupp.py) prompts for a numeric section selection. This choice is passed to download_wordlist_http (around lines 607-613), which reads the base repository URL from the dicturl configuration entry (CONFIG["global"]["dicturl"] defined in cupp.cfg).

The function constructs the full download URL by concatenating the base URL with the selected category and filename:

url = CONFIG["global"]["dicturl"] + category + "/" + filename

# Results in: ftp://ftp.example.com/dictionaries/english/words.gz

The Generic URL Fetcher

Despite its name, download_http serves as the universal fetch mechanism. This function uses Python's urllib.request.urlopen to open the constructed URL:

def download_http(url, targetfile):
    print("[+] Downloading " + targetfile + " from " + url + " ... ")
    webFile = urllib.request.urlopen(url)  # Handles http:// and ftp:// transparently

    localFile = open(targetfile, "wb")
    localFile.write(webFile.read())
    webFile.close()
    localFile.close()

The urlopen call automatically detects the FTP scheme, handles anonymous authentication if required, and returns a file-like object containing the raw bytes. This approach eliminates the need for dedicated FTP libraries like ftplib.

Step-by-Step Execution Flow

The complete workflow executes as follows:

1. User Selection: The operator runs cupp.py -l and selects a dictionary section by number.
2. URL Assembly: download_wordlist_http builds the target URL using the dicturl base path (typically configured around line 73 in cupp.cfg).
3. Directory Creation: The script ensures the local dictionaries/<category>/ directory exists via mkdir_if_not_exists.
4. File Transfer: download_http (lines 606-610 in cupp.py) streams the remote file to local storage using urllib.request.urlopen.
5. Completion: All files for the selected section are saved locally without protocol-specific handling.

Configuring cupp for FTP Downloads

To enable FTP fetching, modify the cupp.cfg configuration file:

[downloader]
dicturl = ftp://ftp.example.com/

Then execute the downloader:

python3 cupp.py -l

# Select the desired number when prompted (e.g., "1")

The script will automatically fetch files via FTP using the same code path as HTTP downloads.

Summary

• The download_wordlist function delegates actual file transfers to download_http in cupp.py.
• urllib.request.urlopen handles both HTTP and FTP schemes transparently, supporting anonymous FTP authentication automatically.
• The dicturl configuration value in cupp.cfg determines whether files are fetched via HTTP or FTP.
• Downloaded files are stored in dictionaries/<category>/ as binary streams without protocol-specific processing.
• No external FTP libraries are required; the implementation relies entirely on Python's standard library.

Frequently Asked Questions

Does the download_wordlist function require special FTP libraries?

No. The function relies on Python's built-in urllib.request.urlopen, which automatically handles FTP connections. The code contains no FTP-specific logic; the same download_http helper processes both HTTP and FTP URLs identically.

How do I configure cupp to use a private FTP server?

Edit the dicturl entry in cupp.cfg to point to your FTP base URL (e.g., ftp://ftp.example.com/dictionaries/). The download_wordlist_http function will concatenate this base with category paths and filenames. Ensure your FTP server allows anonymous access, as the current implementation does not support authenticated FTP sessions.

Where are downloaded wordlists stored locally?

Files are saved to dictionaries/<category>/ relative to the script execution path. The mkdir_if_not_exists function creates this directory structure before download_http writes the binary data to the target filename.

Can download_wordlist handle FTP authentication?

The current implementation uses urllib.request.urlopen without authentication parameters, which only supports anonymous FTP access. For authenticated FTP servers, you would need to modify the download_http function around lines 606-610 in cupp.py to include authentication headers or switch to the ftplib module.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}