Help me fix fiddlercore not capturing software url

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FiddlerCore
Ricky
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Ricky asked on 28 Dec 2021, 02:55 AM

I have used FiddlerCore4.dll to capture the url. But I have the following problem that I don't understand why the error is.
I use fiddler capture request of a program. That program sends 2 urls. But the first url is captured by fiddler. The second url cannot be captured. I copied that 2nd url and pasted it in my web browser and fiddler caught it
Now how do I get the 2nd url from that software program to send?

I have sent a video of my test demo process. You can watch to understand the problem. At the same time, I have attached my 2 programs that I am testing in the video

Link Soft: https://drive.google.com/drive/folders/1nsDn71IQEsEw34Eev5BhdvqfrnrFpcSI

Link Video test: https://youtu.be/KaJ5UL2yq6w

Nick Iliev
Telerik team
commented on 28 Dec 2021, 11:27 AM

Due to security concerns, I can't open the archives you presented in the Google drive link. However, based on your description, it looks like that the issue is not in the URL itself but in the way that your program executes that request. Check if, for some reason, the program is using a different protocol to send that specific request. The fact that the same request is captured when going through the browser indicates that probably your program is hitting one of the following:

- Not going through the system proxy.

- Going through the proxy but failing due to elevated security options (e.g. cert pinning).

- Using different protocol to send the request (Fiddler will capture only HTTP, HTTPS, WebSocket).

Ricky
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commented on 29 Dec 2021, 01:17 AM

Well maybe fiddler core doesn't support catching the above link. I tried using fiddler basic also can't catch it. But I use Httpdebug and HttpAnalyzerV7, the other 2 software can catch it normally.
P/S: The software that sent the request, I couldn't unpack the source, so I couldn't see what protocol they used. If you don't trust the software, you can test it in a virtual machine.
To get the /api.php/Check function you must have any return value for the api /api/auth.

Thank you. I like your program because it is very easy to use. If it is possible to fix this error, Can you quote me a price. I will consider buying your files

Nick Iliev
Telerik team
commented on 29 Dec 2021, 07:12 AM

Both Fiddler Classic and Fiddler Everywhere are MITM proxies, meaning they will capture all HTTP & HTTPS requests through the system proxy. Most likely, the application you are using is not respecting the system proxy or needs additional configuration. If possible, you can share with us the application and the endpoint you are trying to test so that we can investigate further.
Ricky
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commented on 30 Dec 2021, 01:42 AM | edited

I copied the source code from the program, they use xnet. And write some more functions. You can see the source visual studio code I attached. This source httpdebug catches the link.
Looking forward to hearing from you. Have a nice day at work
Nick Iliev
Telerik team
commented on 30 Dec 2021, 07:25 AM

As mentioned before, because of our security policy, we can't open archived files, so I cannot see the shared source. You can share it through a https://github.com/X-rus/xNet source code management tool like GitHub.

Apart from that, you mentioned that the program uses XNet. If we talk about this library, then any traffic that goes through the SOCKS5 proxy won't be captured (as Fiddler doesn't support capturing traffic that goes through a SOCKS proxy).

Skynet
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commented on 07 Jan 2022, 08:38 AM

So what can I do to fix that, I'm looking forward to your response Nick lliev
Rosen Vladimirov
Telerik team
commented on 10 Jan 2022, 08:19 AM

FiddlerCore does not support SOCKS proxy, so there's no easy and out of the box solution. Seems like there's someone who worked on a nuget package for workaround of this issue, you can take a look at it here: https://feedback.telerik.com/fiddler/1361297-socks5-authentication 

No answers yet. Maybe you can help?

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