HTTP Header Manipulation: IP Spoofing

IP spoofing in HTTP headers is a powerful technique for penetration testers to evaluate network security and test server responses. Using web browser modules and command-line tools like cURL, you can manipulate headers such as X-Forwarded-For to simulate various scenarios. However, always ensure you have authorization to perform such tests and follow ethical guidelines to avoid unintended consequences.

Here's how to do it:

Using Browser Plugins and Extensions

Web browser modules and extensions can simulate HTTP requests with custom headers, allowing testers to test in a real browser environment.

• ModHeader: A popular browser extension for Chrome and Firefox that allows you to modify HTTP headers. You can set custom values for headers like "X-Forwarded-For" to test different IP addresses.

  • Set a Request headers with the Name X-Forwarded-For and with Value the IP Address you to impersonate to simulate requests from a specific IP address.

• Requestly: A browser extension that lets you create custom rules for HTTP requests, including header modifications.

  • You can create rules to replace the headers you want to manipulate.
    

• Tamper Data: An extension for Firefox that intercepts HTTP requests and allows real-time modification of headers.

  • Change the headers to simulate requests from various IP addresses.
    

Using cURL for Command-Line Testing

cURL is a command-line tool that can be used to send HTTP requests with custom headers. It's useful for penetration testing because it can simulate complex requests without needing a browser.

• Spoofing with "X-Forwarded-For": curl -H "X-Forwarded-For: 123.123.123.123" http://example.com

• Simulating a Range of IPs: You can script cURL to send requests with different IP addresses to test a server's response to spoofed requests.