Configuring Firefox to work with Burp
To configure Firefox so that you can use it for testing with Burp, you need to perform the following configuration steps.
In Firefox, go to the Firefox Menu and select "Preferences" / "Options".
Select the "General" tab and scroll to the "Network Proxy" settings. Click the "Settings" button.
Select the "Manual proxy configuration" option.
Enter your Burp Proxy listener address in the "HTTP Proxy" field (by default this is set to 127.0.0.1).
Next, enter your Burp Proxy listener port in the "Port" field (by default, 8080). Make sure the "Use this proxy server for all protocols" box is checked.
Delete anything that appears in the "No proxy for" field. Then, click "OK" to close all of the options dialogs.