1. Advanced Web Debugging with Fiddler Eric Lawrence Program Manager Internet Explorer ericlaw@microsoft.com Note: Session includes demos and code samples. For optimal viewing, please sit near the front!

2. TRAFFIC CAPTURE GET /data HTTP/1.1

3. Typical Architecture

4. Debug Across Devices Fiddler Mac Internet SmartPhone Linux PC

5. FiddlerHook for Firefox

6. TRAFFIC IMPORT Fiddler, FiddlerCap, and IE9

7. FiddlerCap FiddlerCap is a lightweight capture tool

8. IE9 Developer Tools IE9’s Developer Tools include a “Network” tab

9. TRAFFIC ANALYSIS Examine Requests and Responses

10. Filtering Traffic Ignore Images & CONNECTs Application Type Filter Process Filter Using QuickExec Using Find

11. Output Options Copy sessions to the clipboard Store as a plaintext file Extract binary response bodies Archive to a database Export a Visual Studio.WebTest file Write your own… Fiddler’s native “Session Archive ZIP” (SAZ) Format

12. Traffic Comparison Use WinDiff to compare HTTP requests and responses.

13. Traffic Comparison “Viewer” mode allows examining multiple captures side-by-side. fiddler.exe -viewer

14. TRAFFIC MODIFICATION Rewriting HTTP(S) Traffic

15. Automated Rewrites Simple Built-in Rules The HOSTS extension

16. Breakpoint Debugging Use Fiddler inspectors to modify requests and responses….

17. Understanding Streaming Timeline view of Buffering Mode Timeline view of Streaming Mode

18. Request Builder Create hand-built HTTP requests, or modify and reissue a request previously captured.

19. Simple Filters Flag, modify or remove headers from all requests and responses.

20. AutoResponder Replay previously captured or generated traffic.

21. SCRIPTING AND EXTENSIBILITY Powering Up Fiddler

22. Understanding Extensibility Fiddler 2 Fiddler ScriptEngine Inspector2 IFiddlerExtension Fiddler Proxy ExecAction.exe Your FiddlerScript Xceed*.dll Makecert.exe Your Automation

23. FIDDLERSCRIPT Lightweight extensibility using JavaScript

24. FiddlerScript

25. FiddlerScript: Request Modification static function OnBeforeRequest(oS: Session){ if (oS.uriContains(".aspx")) { oS["ui-color"] = "red"; } if (m_DisableCaching){ oS.oRequest.headers.Remove("If-None-Match"); oS.oRequest.headers.Remove("If-Modified- Since"); oS.oRequest["Pragma"] = "no-cache"; }

26. FiddlerScript: Response Modification static function OnBeforeResponse(oS: Session) { oS.utilDecodeResponse(); oS.utilPrependToResponseBody("Injected Content!"); }

27. EXTENSIONS Powerful extensibility using any.NET Language

28. neXpert

29. Watcher http://websecuritytool.codeplex.com/ Automated (passive) security analysis

30. TEST INTEGRATION Integrating Fiddler into your tools

31. ExecAction The ExecAction.exe command line utility calls into the OnExecAction function in script and Fiddler extensions.

32. FiddlerCore Fiddler 2 Fiddler ScriptEngine Inspector2 IFiddlerExtension FiddlerCore ExecAction.exe YourApp.exe FiddlerCore Fiddler application with extensionsYour application hosting FiddlerCore Your FiddlerScript Xceed*.dll Makecert.exe

33. Programming with FiddlerCore // Call Startup to tell FiddlerCore to begin // listening on the specified port, register as // the system proxy and decrypt HTTPS traffic. Fiddler.FiddlerApplication.Startup(8877, true, true); Fiddler.FiddlerApplication.BeforeResponse += delegate(Fiddler.Session oS) { Console.WriteLine ("{0}:HTTP {1} for {2}", oS.id, oS.responseCode, oS.fullUrl); }; // Call Shutdown to tell FiddlerCore to stop // listening and unregister as the system proxy Fiddler.FiddlerApplication.Shutdown();

34. Call To Action Try the Watcher & neXpert extensions Use FiddlerCap to collect traffic from the field Check out import from the IE9 Developer Tools

35. Questions and Resources Resources o Meet the IE Team in the MIX “Commons” o http://www.fiddler2.com/mix/ o ericlaw@microsoft.com Please fill out an evaluation form for this session ( FT-50 ). Thank you!