Questions on Fiddler Forum

1 answer

281 views

Export Sessions to Visual Studio WebTest removes Referer headers

Is there a way to control which headers that are filtererd out during an export of sessions to a Visual Studio WebTest file?

Since Microsoft is dropping support for both IE11 and Visual Studio Loadtesting features, the Web Test Recorder is becoming more and more of a problem for recording webtest files. For that reason we have started to use Fiddler instead, but noticed several draw backs, the worst being that all requests have the Referer header removed during export (even with ALL options disabled during save).

Another draw back is that Fiddlers option to handle Redirects in such export does not seem to be working. Requests that are caused by the browser following a redirect har exported like any other normal request (in the webtest request the option is set to Follow Redirects on all of these as well). We can handle this problem manually and remove the requests in a redirect chain, but the Referer header removal is a bigger problem.

If this is not available as a config setting somewhere, is it possible to change this behaviour? If not, is it possible to get the code for the export plugin so we can modify the behaviour? If that is not possible, can we create/code our own plugins to the WebTest exporter?

Fiddler Classic

answered on 27 Sep 2021

3 answers

628 views

Cert error when using Fiddler with the AWS CLI

This seems like a new problem, because I am sure this used to work. I'm using the Amazon Web Services command-line interface (CLI). This makes https calls using Python. If Fiddler is running, I can see 200 responses that show that tunneling is working, and I get the correct results for the command. However, if then enable decryption, things go south. I get a string of 5 tunnel requests (all with 200 responses):

CONNECT iam.amazonaws.com:443 HTTP/1.0
Host: iam.amazonaws.com:443
A SSLv2-compatible ClientHello handshake was found. Fiddler extracted the parameters below.
Version: 3.1 (TLS/1.0)
etc.

After 5 attempts, the command itself on the command line returns this error:

[Errno 1] _ssl.c:504: error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed

Is there something I can do to configure Fiddler _with_ HTTPS decryption that will work with the AWS CLI?

Fiddler Classic

answered on 27 Sep 2021

0 answers

1.2K+ views

Newbie: Trying to use Fiddler to see/debug Javascript/XHR problem

Hi,

I am doing some testing with a scenario where I have an HTML page with some Javascript that uses XHR to do a cross-domain request for a resource that is in a different domain, and I am trying to use a CORS Proxy called "CORS Anywhere" to determine if that will work.

I have a basic test configuration for this scenario working, but some of the resources (URLs) that we need to access (using the Javascript/XHR are "protected" by Oracle "OAM" web access control product, and my test fails when that is the case.

The way that OAM works is that there is an agent (webgate) on the Apache that is hosting the target resource, and when the webgate sees a request incoming for the protected resource, the webgate will cause a 302/redirect response to occur, and I think that that is the start of the problem.

[In the Apache logs, I can the request for the resource, and a 302 redirecting to one of the OAM endpoints, so I am pretty sure that that first OAM redirect is occurring.]

I have been trying various things to try to "see" what is going on, including the web developer tools, etc., and live headers plugin for the browser (both Chrome and Firefox), but with those, I only see the initial request and the last request for the resource, and that last one is failing.

I have also tried sniffers, including Wireshark, but our dev environment is on AWS, and even with Wireshark and the capture in promiscuous mode, I don't see all the requests, especially the request form the Javascript/XHR and the redirects that I believe are being caused because of the webgate.

So, I am now trying to use Fiddler.

However, even when I use Fiddler, I am only seeing the first request and the final request. The requests from the Javascript/XHR to just prior to the last request are not appearing at all :(!!

So I was wondering: Shouldn't Fiddler be able to capture those requests (and responses) that appear to be missing? Is there something else that I need to configure in order for Fiddler to be able to "see" those requests?

Here's the HTML/Javascript/XHR page that is doing the request to the target URL:

<html>
<body>

<script>
// 1. Create a new XMLHttpRequest object
let xhr = new XMLHttpRequest();

// 2. Configure it: GET-request for the URL /article/.../load
xhr.open('GET', 'http://192.168.xxx.yy:8080/http://charlieeastweb.....com:7777/target-charlie/index.html');


// 3. Send the request over the network
xhr.send();

// 4. This will be called after the response is received
xhr.onload = function() {
  if (xhr.status != 200) { // analyze HTTP status of the response
    alert(`Error ${xhr.status}: ${xhr.statusText}`); // e.g. 404: Not Found
  } else { // show the result
    alert(`FROM javascript in xhr-fakewava-PROTECTEDPAGE.html, Done, got ${xhr.response.length} bytes`); // response is the server response
  }
};

xhr.onprogress = function(event) {
  if (event.lengthComputable) {
    alert(`FROM javascript in xhr-fakewava-PROTECTEDPAGE.html, event.type is: ${event.type}`);
    alert(`FROM javascript in xhr-fakewava-PROTECTEDPAGE.html, event.lengthComputable is true, Received ${event.loaded} of ${event.total} bytes`);
  } else {
    alert(`FROM javascript in xhr-fakewava-PROTECTEDPAGE.html, event.type is: ${event.type}`);
    alert(`FROM javascript in xhr-fakewava-PROTECTEDPAGE.html, event.lengthComputable is false, Received ${event.loaded} bytes`); // no Content-Length
  }

};

xhr.onerror = function() {
  alert("Request failed");
};

</script>

</body>
</html>

In the above, the:

'http://192.168.xxx.yy:8080/http://charlieeastweb.....com:7777/wavatarget-charlieeastweb05/index.html'

is a kind of "composite" URL:

the "http://192.168.xxx.yy:8080" is the URL of the CORS Anywhere CORS proxy server (actually on the same machine as the Apache that is serving the HTML page).

The

http://charlieeastweb.....com:7777/target-charlie/index.html

is the URL of the protected target resource.

So I think/GUESS that:

Browser makes a request for the HTML page that contains the Javascript/XHR code, then <== [This is the 1st request I see in Fiddler - response is 200/OK]
The Javascript/XHR code make request, which goes to the http://192.168.xxx.yy:8080 (which is the CORS Anywhere server), then
CORS Anywhere takes the request and forwards it to the http://charlieeastweb....com:7777/target-charlie/index.html (the resource, protected by OAM, then
When the OAM webgate gets that request, it sends the first 302 response back.
etc.?

The 2nd (and only) other request/response I see in Fiddler is a request to the http://charlieeastweb....com:7777/target-charlie/index.html. The response to this 2nd request is a 200/OK. This request includes an "Origin:" HTTP request header, and the response includes an "access-control-allow-origin" HTTP response header, which I believe is being added by the CORS Anywhere CORS Proxy.

However, the contents of the page that is in that response is an error page that we see when the OAM processing has failed, so something is going wrong within the OAM part of the protocol, but I am not able to see anything :(!!

I am really new to using Fiddler, and to get it to start logging, I followed steps to set up Chrome with a proxy at localhost:8888.

Is it possible that maybe the reason Fiddler is not logging the requests/responses that appear to be missing is that once the Javascript/XHR makes the request to the protected URL, the ensuing redirects are not going through/not using the Chrome proxy settings???

If so, what additional configuration do I need?

Thanks!

Jim

Fiddler Classic

updated question on 26 Sep 2021

1 answer

429 views

Unable to launch google drive file stream app when fiddler capture is enabled.

1.Downloaded, installed google drive file stream desktop application.

2.Tried to launch application and click on sign in button.

3.Then login page got opened over browser there asked for login credentials to authenticate.

4.Provided required credentials. then asked for sign in clicked on signin button

5.Login got succeeded but Failed to launch google drive file stream app when fiddler is opened to capture the traffic.

6. Downloaded logs drive_fs enabling verbose mode in app settings.

7.Found curl 60 error as shown in attachment

8.When we see all logs observed ssl verification is done with C:\Program Files\Google\Drive File Stream\51.0.9.0\config\roots.pem

Is there any process or procedure to update certificate in above provided location to access app through fiddler?

Fiddler Classic

FiddlerCore

answered on 22 Sep 2021

0 answers

231 views

Not able to see some trafic from Android device

On Android 10 device after all steps from the tutorial - I'm able to see some traffic from my app I'm trying to debug, for example, some requests that are sent to AppCenter.ms in plain text decrypted from https, but not anything else what is very weird:)

Mobile

Windows

asked on 15 Sep 2021

2 answers

199 views

Is it possible to view NHtmlUnit web requests in Fiddler?

I am using NHtmlUnit on Windows 10 which is a headless browser Javascript engine which I've downloaded from Nuget. NHtmlUnit allows me to request and download webpages using a standard Url e.g. http://someurl.co.uk but I cannot seem to see these requests appearing in Fiddler (Classic). Have I configured Fiddler incorrectly? Or because NHtmlUnit IS a headless browser I am never going to see them? Grateful for any help - thanks

Fiddler Classic

Windows

answered on 13 Sep 2021

0 answers

120 views

fiddler

fiddler打开就崩溃

Fiddler Classic

asked on 12 Sep 2021

1 answer

226 views

Is there any way to save partial stream of an interrupted session in fiddler?

Hi,

I'm trying to save streaming to disk file. However, the stream sometimes is interrupted by unstable internet connection. Then I got a 504 error saying ReadResponse() failed:The server did not return a complete response for this request.

But I can see some bytes are already downloaded. Is there any way to save the downloaded bytes to a file?

I tried the OnBeforeResponse() event in FiddlerScript. But the event is not fired when 504 error occurs.

Best regards,

Fiddler Classic

answered on 10 Sep 2021

0 answers

184 views

body was omitted when exporting to HAR 1.2

Hi

I have set the prefs very high (prefs set fiddler.importexport.HTTPArchiveJSON.MaxTextBodyLength 600000000000) but fiddler is still omiting response body.

The current issue is with a request with Response Content-Length: 2175586 and it is being omitted. Can you tell me how to make fiddler not use a limit at all.

Fiddler Classic

asked on 03 Sep 2021

1 answer

177 views

Log

Hello. I intend to use the program without stopping long enough. I express concern that Log may worsen the program's performance. I want to disable it, how do I do this?

Fiddler Classic

Windows

answered on 02 Sep 2021