Configuring the proxy settings in Firefox:
- Launch Firefox, then after that, pick the icon labeled “Customize your new tab page.”
- To change the network settings, first pick General, then scroll down until you reach the section labeled Network Settings, and then select Settings.
- On the page that displays Connection Settings, choose the option to Use system proxy settings, and then click the OK button.
Trusting the certificate:
- Launch Fiddler 4, then navigate to the Tools menu, then select Options.
- Navigate to the tab labeled HTTPS.
- After selecting Actions from the drop-down menu, choose to Export Root Certificate to Desktop.
- Launch Firefox once more, and then click the button labeled “Customize your new tab page.”
- After selecting Privacy & Security from the drop-down menu, navigate to the bottom of the page to the Certificates section, and then select View Certificates.
- On the page for the Certificate Manager, pick Import from the drop-down menu that appears after clicking the Authorities tab.
- Select the FiddlerRoot.cer file that you have saved on your Desktop, and then click the Open button.
- In the window to edit the trust settings for the CA certificate, check the box indicating that “This certificate can identify websites” and then choose OK.
Because of this modification, Firefox will now respect the root certificate for the Fiddler application, and it will function correctly when used in conjunction with the Fiddler application.