How can I exempt all in FiddlerCore as if I was using the Win Config option in Fiddler Classic? Thank you in Advance!

Is it possible with Fiddler Core to completely replace a response like its possible with Fiddler Classic to do in the "RAW" section if you put a breakpoint before the Response?

Thanks

I would like to suggest that Fiddler products be added to the Progress Control Panel to allow better management of updates and installations.

I know that Fiddler uses local DNS resolver as it didn't work on some test sites that only worked through DoH geobypassing proxy. Are there any trick/method to make Fiddler respect browsers DoH setting? If not, would you guys please consider adding it since DoH/DoT seems to be very useful/popular these days.

Here's some use case scenarios

• You want to hide your DNS queries from your ISP while doing Fiddler session on a browser.
  
• Your ISP filters your DNS (transparent DNS proxy, etc) and you want to debug sites that are blocked by your ISP with Fiddler.
• You want to debug geo-blocked sites which can be bypassed by geo-bypassing DoH resolver.
• and so on.

You can also add following to any of the scenarios above if we think alternative solutions like using Windows 10/11, configuring DoH on the router, using VPN, etc.

• "you use an operating system that doesn't support configuring DoH/DoT"
• "your ISP/Organization blocks VPN/proxies"
• "your router doesn't support DoH/DoT"

BTW, I know Microsoft natively added DoH in Windows 10 more than a year ago, DoT to Windows 11 insider build a few months ago. I don't know if Fiddler works on them (works as in properly using DoH/DoT) as i don't use those OSes. I am curious to know about it though.

Anyways,

Here's quick guide to confirm that Fiddler/Firefox bypasses DNS-over-HTTPS just in case anyone wants to test.

Open Firefox (Use this guide for other browsers)

1. Click the menu button and select Settings.
2. In the General panel, scroll down to Network Settings and click the Settings… button
3. Check "Use system proxy settings"
   
4. Scroll down to Enable DNS over HTTPS.
5. • On: Select the Enable DNS over HTTPS checkbox.

     Check Custom and paste this server (this is DoH DNS resolver that blocks social media sites we are using for the test)
     

   • https://freedns.controld.com/p3
     

   • Press OK

6. Open www.facebook.com and it should be blocked.

7. Now open Fiddler and try to open www.facebook.com again on the browser. Facebook will work.
   

Within a .net application when the CheckCertificateRevocationList is set SSL connections can no longer be made while fiddler is running.

An example:

ServicePointManager.CheckCertificateRevocationList = true;

WebRequest request = WebRequest.Create("https://www.google.com");

var response = await request.GetResponseAsync();

This fails with

The remote certificate is invalid according to the validation procedure.

 

If I register a validation callback (ServicePointManager.ServerCertificateValidationCallback) too  see what is going on I see

SSLPolicyErrors = RemoteCertificateChainErrors

When looking at the X509Chain I see "The revocation function was unable to check revocation for the certificate.\r\n"

Some other threads on stack overflow indicated this may be due to no revocation list being attached to the fiddler root certificates.

So I was wondering if anyone was able to get fiddler to work with the CheckCertificateRevocationList= true.  I know I can disable it but that would not be good for security. I also could in the handler allow fiddler certificates, but I was hoping there was a way to generate the fiddler certificates in a way that worked with that setting.

 

can you confirm Log4j or Log4j2 being used in "Progress Software Telerik Fiddler 4"

.NET application show error message below when I close Fidler program on Windows Server (Production Environment)

System.Net.Sockets.SocketException: No connection could be made because the target machine actively refused it 127.0.0.1:8888

If I open the Fidler program again, this error will be lost. I think this error occurred because the Filder does not roll back some settings after closing. So system still routes to 127.0.0.1:8888.

But after closing Fidler program I have checked the Internet option. It rollbacks properly (Use proxy server is unchecked).

Have other configuration that Fidler have changed? Or how to reset the proxy setting?

Currently, I work around by opening Filder program always.

Please help to solve this problem.

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?

I am working on fiddler core with C#. But FiddlerApplication.Shutdown(); I don't think your command works. FiddlerApplication.Shutdown(); After the application, the internet access of the current computer is turned off. When the fiddler core application is closed, as in the picture I shared, internet access is cut off when the fiddlerapplication.shutdown command is applied.

How can I solve this problem?

 

For example, we cannot access any websites or internet when the internet is disconnect ;

 

Note: This problem happens when I close and open the program 3 or 5 times.

Hello,

I have attached the source code of my work. When the program opens, it installs a certificate and asks such questions. I want it to install and pass the fiddler certificate without asking this question. Is it possible?

A "yes, no" screen appears like this while installing the certificate. I want it to install without asking. (Hidden Install Certificate) Is that possible?