Secure Fetch

Secure fetch to prevent access to local resources

GitHub

Secure Fetch

This project implements a secure URL fetching tool using FastMCP.

Prerequisites

  • Python 3.7+
  • uv (Python package installer and environment manager)

Installation

  1. Install uv if you haven't already:

pip install uv

  1. Create a new virtual environment and install dependencies:

uv venv source .venv/bin/activate uv pip install fastmcp requests

Usage

  1. Set the allowlist environment variable (optional):

export SECURE_FETCH_ALLOWLIST="example.com,trusted-domain.org"

  1. Run the script:

uv run main.py

Features

  • Fetches URLs securely
  • Resolves domains to IPs
  • Checks for private/internal IPs
  • Handles redirects (up to 3)
  • Supports custom HTTP methods and headers
  • Uses an allowlist for trusted domains/IPs

Security Considerations

  • The tool prevents access to private/internal IPs unless explicitly allowed
  • Only HTTP and HTTPS schemes are permitted
  • SNI is set to match the hostname for HTTPS connections

Example Usage

Once the script is running, you can use the fetch_url function to securely fetch URLs. The function will return a dictionary containing the status code, response body, and content length.

Note

This tool is designed for secure URL fetching. Always review and understand the code before using it in your environment.

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