Fiddler: Intercepting HTTP(S) traffic in Java Applications

To change the Java Virtual Machine's proxy settings, add the following lines at the beginning of your code.

System.setProperty("http.proxyHost", "127.0.0.1");
System.setProperty("https.proxyHost", "127.0.0.1");
System.setProperty("http.proxyPort", "8888");
System.setProperty("https.proxyPort", "8888");

Fiddler: Faking server responses using AutoResponder

Fiddler is a free web debugging proxy tool that records all HTTP(S) traffic between your computer and the internet.

Fiddler is great for capturing and manipulating HTTP(S) traffic.

I regularly use Fiddler to reproduce specific scenario’s by returning a response from my local disk instead of hitting the server.

Steps:

1. Install Fiddler.

2. Clear your cache by selecting Tools -> Clear WinNET Cache from the main menu or use the keyboard shortcut Ctrl + Shift + X.

3. Select the AutoResponder tab in the right hand side pane.

4. Check Enable automatic responses, to activate AutoResponder.

5. Check Unmatched requests passthrough, so that requests that do not match are sent to the server. If this option is not checked, Fiddler will respond to all HTTP(S) request that do not match the rule with a 404 Not Found.

6. Drag and drop traffic items from the web session list on the left into the AutoResponder pane on the right hand side.

7. Select the rule, and then compose a pattern and response using the rule editor at the bottom of the AutoResponder pane.

8. Remember to click the Save button.

9. From the main menu select File -> Capture Traffic or use the keyboard shortcut F12.