Fiddler not monitoring proxy traffic

[Marko]

I want to monitor one .exe application that takes in HTTPs proxies as argument and sends HTTPs requests towards some external site using those proxies. If i select in that program that i don't want to use proxies but rather localhost IP, Fiddler easily tracks it down, but when i start using those proxies as an argument instead localhost IP, none single request is being shown. Is there any way to fix this and show this traffic from this app when using proxies? Thanks in advance.

[Eric R | Senior Technical Support Engineer]

Hi Marko,

Thank you for using the Fiddler Forums. I believe this requires Fiddler to Chain to an Upstream Proxy. Although, I am not completely certain this will meet the requirement. Let me explain in more detail below.

Fiddler debugs traffic by acting as a Man-in-the-Middle between the client and server. It appears that the .exe sends traffic through multiple proxies and Fiddler cannot only capture with a single proxy. See the Understanding Fiddler blog post for more details.

Alternatively, it might be help to Capture Traffic from .NET Services with Fiddler. This requires configuring the machine.config and adding a defaultProxy setting that points to Fiddler.

If neither of the above options works, can you provide more details on how the .exe works with other proxies?

Please let me know if you need any additional information. Thank you.

Regards,

Eric R | Senior Technical Support Engineer
Progress Telerik