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For study purposes I tried to make a simple app to learn capturing web traffic. but it didn't capture any traffic. Can you help me to figure out what is wrong here:

 

        void Start()
        {
            FiddlerApplication.Prefs.SetBoolPref("fiddler.certmaker.CleanupServerCertsOnExit", true);
            FiddlerCoreStartupSettings startupSettings =
                new FiddlerCoreStartupSettingsBuilder()
                    .ListenOnPort(8888)
                    .DecryptSSL()
                    .OptimizeThreadPool()
                    .Build();

            CertMaker.createRootCert();
            FiddlerApplication.Startup(startupSettings);
            FiddlerApplication.AfterSessionComplete += FiddlerApplication_AfterSessionComplete;
        }

        private void FiddlerApplication_AfterSessionComplete(Session oSession)
        {
            string reqHeaders = oSession.oRequest.headers.ToString();
            var reqBody = Encoding.UTF8.GetString(oSession.RequestBody);

            string respHeaders = oSession.oResponse.headers.ToString();
            var respBody = Encoding.UTF8.GetString(oSession.ResponseBody);

            string output = reqHeaders + "\r\n" +
                (!string.IsNullOrEmpty(reqBody) ? reqBody + "\r\n" : string.Empty) +
                "==========================================================" + "\r\n\r\n" +
                respHeaders + "\r\n" +
                (!string.IsNullOrEmpty(respBody) ? respBody + "\r\n" : string.Empty) +
                "==========================================================" + "\r\n\r\n";

            BeginInvoke(new Action<string>((text) =>
            {
                textBoxTraffic.AppendText(text);
            }), output);
        }

Eric R | Senior Technical Support Engineer
Telerik team
 answered on 19 Aug 2019
2 answers
752 views

Hi good morning, please I need your support for use Telerik in Centos 7.

Will  I Install Telerik in Centos 7?

Regards

Xochitl
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Rank 1
 answered on 19 Aug 2019
2 answers
222 views
Got stuck in Creating Proxy while starting. Please find the attached screenshot for reference 
Shivaraj
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 answered on 19 Aug 2019
2 answers
360 views

I've encountered an interesting problem when trying to debug digest authentication in my company's application using Internet Explorer 11 (11.0.9600.19377 on Windows 7 64-bit) with Fiddler (v5.0.20192.25091). It seems that with Fiddler running and capturing traffic, the behaviour of IE11 is actually different, suggesting that Fiddler is modifying the outgoing traffic before it hits the server.

To give a bit of context, using Chrome and Firefox (with or without Fiddler running) I'm finding that the digest auth. process works entirely as expected:

  1. Client sends a GET request without an authorisation header to a protected URL.
  2. Server responds with 401, including a nonce and realm.
  3. Client prompts user for username & password.
  4. Client sends a secondary GET request to the same URL, including a full authorisation header (username, password, nonce & realm).
  5. The server responds with 200.

When using IE11 without Fiddler, the process is incorrect – I've been able to analyse this by using Wireshark:

  1. Client sends a GET request without an authorisation header to a protected URL.
  2. Server responds with 401, including a nonce and realm.
  3. Client prompts user for username & password.
  4. Client repeats step (1), causing a loop. The client is therefore unable to authenticate.

However, when using IE11 with Fiddler running and capturing traffic, the browser behaves differently (following the same process as Chrome and Firefox) and actually works correctly. My understanding was that Fiddler is completely transparent (capturing all WinINET traffic without modification) so that leaves me with a few questions:

  • What processing does Fiddler apply to requests before passing them to the server?
  • Is there an option to bypass this processing so that I can analyse the 'raw' requests?
  • Alternatively, does Fiddler do anything specifically to modify the browser behaviour while it is capturing traffic?
DB
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Rank 1
 answered on 15 Aug 2019
3 answers
26.5K+ views
I've been using Fiddler for years, but the most recent version I've installed (v4.4.8.4) no longer captures any traffic.

- The Filters are turned off (and using the "Troubleshoot Filters" doesn't appear to change anything)
- Traffic does not appear in Fiddler when I visit http://ipv4.fiddler:8888
- However, traffic *does* appear when I visit http://localhost:8888

Does anyone have a suggestion?

Thanks.
Eric R | Senior Technical Support Engineer
Telerik team
 answered on 14 Aug 2019
1 answer
339 views

I've added the following line to static `function Main()` :

 

    CertMaker.StoreCert("api.some.service.com", "C:\\Bla.pfx", "Secret");

But when I try to do a get I still get a cert with the following info:

 

Server certificate:
*  subject: OU=Created by http://www.fiddler2.com; O=DO_NOT_TRUST; CN=*.some.service.com
*  start date: Aug  8 14:29:55 2018 GMT
*  expire date: Nov  6 14:29:55 2021 GMT
*  subjectAltName: host "api.some.service.com" matched cert's "*.some.service.com"
*  issuer: OU=Created by http://www.fiddler2.com; O=DO_NOT_TRUST; CN=DO_NOT_TRUST_FiddlerRoot

The way I tested it was by performing the following call :

sudo curl -x "my.fqdn:9999" --http1.1 --cacert ./FiddlerRoot.pem  -v -sSi https://api.some.service.com/SomeFunc

Eric R | Senior Technical Support Engineer
Telerik team
 answered on 14 Aug 2019
1 answer
208 views

Hi,

I've similar need as mentioned in another post: https://www.telerik.com/forums/automatic-saving-of-responses-into-autoresponder, but don't want to pile up the AutoResponder. The AutoResponder UI is a simple list view and when I pull SAZ sessions, I'm finding it difficult with other existing rules. I wonder if something can be done programmatically to locate the session in a SAZ file and serve the response accordingly bypassing the UI. I'm using below code snippet to locate a session in the SAZ, but not finding a way to serve the response body stored in SAZ file.

for (var i1:int = 0; i1<sSessions.Length; ++i1)
{
    FiddlerObject.log("sSessions: " + i1 + ": " + sSessions[i1].url);
 
    if(sSessions[i1].url === 'example.com/default.css') {
        //FiddlerObject.log("sSessions: " + i1 + ": " + sSessions[i1].GetResponseBodyAsString());
        //TODO logic to map oSession.response = response stored in SAZ file
    }
}

 

Can anyone help? The above sample code snippet may not be the best one, and appreciate for improved version.

Cheers,

Rohit
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 answered on 14 Aug 2019
5 answers
382 views

Please forgive me if this has been addressed elsewhere but I cannot find anything to help....

I have been pointed in the direction of Fiddler after running into problems using the IIS SEO Toolkit, which does not work if a site does not have TLS 1.0 enabled. The original thread can be seen at https://forums.iis.net/t/1236833.aspx?IIS+SEO+Toolkit+Not+Crawling+Sites+w+TLS+1+0+Disabled+.

Fiddler is suggested as a cure for this problem but I am not having any luck getting it to allow the crawler to run. I have used the following code in the custom rules:

 

if (oSession.HTTPMethodIs("CONNECT") && oSession.HostnameIs("www.yourdomain.com")) { 
  oSession["x-OverrideSslProtocols"] = " ssl3;tls1.0;tls1.1;tls1.2";
}

 

The aim is to allow Fiddler to act as a proxy so that the IIS software can use TLS 1.0 to speak to Fiddler, which can then use TLS 1.1+ to access the website. 

Is there a Fiddler genius who can help make this work? I know that you will be doing a lot of people a huge service.

Many thanks,

Joe

Eric R | Senior Technical Support Engineer
Telerik team
 answered on 13 Aug 2019
3 answers
880 views

Hello, I have faced some problem https decrypt. when I click to decode response body. this error to occur. Any idea ?

 

Thank you.

 

Eric R | Senior Technical Support Engineer
Telerik team
 answered on 13 Aug 2019
1 answer
489 views

Hello,

I am trying to enable "Decrypt HTTPS Traffic" in Fiddler (Tools > HTTPS) and I keep getting an error in the log file.

 

I tried "Trust Root Certificate" but I get an error that it can't be found (Refer to attached log)

I tried to reset both the interception cert and all cert and I still get the error (refer to attached log)

I tried to reset Windows Network Settings, nothing.

I tried to run Fiddler as Admin, nothing. 

 

The only time this worked was earlier before when I reset my Windows PC to a fresh installation, then I actually get the popup saying Scary Text ahead. But sadly I faced more issues after that and reset all certificates in the actions menu and now I am back to square one.

 

 

I am on Windows 10 1809, but I've also tried to do this on Windows 10 1903 but I am getting the same error. Any help is definitely appreciated!

 

Thank you,

 

Matt.

Eric R | Senior Technical Support Engineer
Telerik team
 answered on 13 Aug 2019
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