Fiddler Ideas

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Support .NET Core / WCF projects by registering as a proxy for WinHTTP

Related to forum thread:

We found that .NET Core projects use WinHTTP instead of WinINET. As Fiddler registers itself only as a proxy for WinINET, traffic from these projects do not show up in Fiddler. While a manual workaround exits, it would be good if there was at least an option to register Fiddler as a proxy for WinHTTP as well.

On a side note: We've seen that even node.js traffic does not show in Fiddler as well. We've not researched the cause as it wasn't critical to us at that time. But, it could also be due to the same reasons.

  • Guest
  • May 30 2018
  • Under review
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  • Guest commented
    18 Jun, 2018 01:53am

    So, the information I can give you Eric, is that as per the thread, a .NET core app's traffic doesn't show in Fiddler unless I run  unless I run
    netsh winhttp set proxy

    And once I do 
    netsh winhttp reset proxy

    the traffic stops showing up again.

  • Eric Lawrence commented
    5 Jun, 2018 04:07pm

    I would be very surprised to find that .NET Core is really based on WinHTTP, as the .NET team has their own HTTP implementation. You'll need to find out where it gets its proxy settings if it's not using the system settings (what you're calling "WinINET proxy" above).

    With regard to node, yes, many node HTTP libraries don't offer explicit control of the proxy at all, and I'm not aware of any that automatically adopt the system's proxy settings. You'll need to explicitly configure your node code to proxy through Fiddler.