HTTPS traffic not captured using FiddlerCore on Linux

[Cosmin]

01.

public class ProxyConfig

02.        {

03.            private const string SecureEndpointHostname = "localhost";

04.            private readonly int _secureEndpointPort = 18888;

05. 

06.            private static readonly ICollection<Session> AllSessions = new List<Session>();

07. 

08.            private static Fiddler.Proxy _secureEndpoint;

09. 

10.            private static readonly LoggerCnx Logger = new LoggerCnx();

11. 

12.            public void SetupProxyListener()

13.            {

14.                // This is a workaround for known issue in .NET Core - https://github.com/dotnet/coreclr/issues/12668

15.                CultureInfo.DefaultThreadCurrentUICulture = new CultureInfo("en-US");

16. 

17.                FiddlerApplication.BeforeRequest += session =>

18.                {

19.                    // In order to enable response tampering, buffering mode MUST

20.                    // be enabled; this allows FiddlerCore to permit modification of

21.                    // the response in the BeforeResponse handler rather than streaming

22.                    // the response to the client as the response comes in.

23.                    session.bBufferResponse = false;

24.                    lock (AllSessions)

25.                    {

26.                        AllSessions.Add(session);

27.                    }

28.                };

29. 

30.                Logger.Info($"Starting {FiddlerApplication.GetVersionString()}...");

31.                CONFIG.IgnoreServerCertErrors = true;

32.                CONFIG.bCaptureCONNECT = true;

33. 

34.                FiddlerApplication.Prefs.SetBoolPref("fiddler.network.streaming.abortifclientaborts", true);

35. 

36.                FiddlerCoreStartupFlags startupFlags = FiddlerCoreStartupFlags.Default;

37.                startupFlags = (startupFlags | FiddlerCoreStartupFlags.DecryptSSL);

38. 

39.                FiddlerApplication.Startup(BaseConfiguration.ProxyPort, startupFlags);

40. 

41.                Logger.Info("Created endpoint listening on port {0}", BaseConfiguration.ProxyPort);

42. 

43.                Logger.Info("Starting with settings: [{0}]", startupFlags);

44.                Logger.Info("Gateway: {0}", CONFIG.UpstreamGateway.ToString());

45. 

46.                // Create a HTTPS listener, useful for when FiddlerCore is masquerading as a HTTPS server

47.                // instead of acting as a normal CERN-style proxy server.

48.                _secureEndpoint = FiddlerApplication.CreateProxyEndpoint(_secureEndpointPort, true, SecureEndpointHostname);

49.                if (null != _secureEndpoint)

50.                {

51.                    Logger.Info("Created secure endpoint listening on port {0}, using a HTTPS certificate for '{1}'", _secureEndpointPort, SecureEndpointHostname);

52.                }

53.            }

54.}

 

Trying to capture all traffic from browser using FiddlerCore using the .NetStandard libraries. Above is what I have.

 

Everything seems to work fine on Windows, all traffic is captured, HTTP and HTTPS.
The problem arises when I'm trying to do the same when running the code on Linux (tried it on both VM and Linux conainer, Ubuntu 16.04).
Any idea what I'm I'm missing?

[Alexander]

Hi,

Have you set the proxy settings of the machine? This should be done manually on OSs different than Windows.

Regards,
Alexander
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