Intro

 Fiddler is a free web debugging proxy which logs all HTTP(s) traffic between your computer and the Internet.

Download And Install

• Download: https://www.telerik.com/download/fiddler-everywhere (requires email). Try this: https://api.getfiddler.com/win/latest

  • https://telerik-fiddler.s3.amazonaws.com/fiddler/FiddlerSetup.exe

  • https://downloads.getfiddler.com/win/Fiddler Everywhere 1.0.2.exe

• Install Fiddler as an Administrator

Documentation

• Fiddler’s YouTube playlist of how to use the tool: https://www.youtube.com/playlist?list=PLvmaC-XMqeBbw72l2G7FG7CntDTErjbHc

• Good write up on different Fiddler configurations

• Configure .NET Applications

.NET Applications

To allow the .NET Framework to automatically connect to Fiddler, you need to change your app.config to use a proxy as detailed here: Configure .NET Applications.

See my notes here:How To: Configure An HTTP Proxy For .NET Applications

All Web Traffic

When Fiddler is installed on a host, it acts as a proxy by listening on port 8888. You can direct all web traffic to Fiddler using this command that uses the local host address (127.0.0.1)

More info on netsh here: How To: Configure A Web Proxy Using Netsh

Fiddler Configuration

Enter this command in Fiddler’s cmd box to direct traffic to the HostName

Configuring Fiddler

To decrypt HTTPS traffic, you need to have Fiddler terminate the HTTPS connections and thus, you must allow it to generate and install its own root certificates in Windows.

• Tools → Options → Decrypt HTTPS traffic

Open