Can't filter to show only localhost

[Avrohom Yisroel]

I'm trying to debug a WPF client that talks to a WCF service, all running in Visual Studio. The service project (that holds the WCF services) is configured to use port 50000, and the WPF client has end points for that in the app.config.

I changed the WPF client to use localhost.fiddler:50000, which shows the requests in Fiddler, but I'd like to filter out everything else, so I only see these requests. However, I can't get the filtering to work.

If I enable filters, and set it to show only localhost.fiddler:50000 and localhost:50000, then when the WPF client makes a request, I see an entry for 
localhost:50000 in Fiddler, but this disappears as soon as the request has completed, so I can't inspect it.

I tried clearing the hosts filter, and telling it to show only intranet hosts, but this didn't show anything.

The weird thing is that if I set it to hide the most common hosts that I don't want (things like Skype, Teams, etc), then I get the same behaviour as above, ie the 
localhost:50000 requests appears briefly, and then disappears. The same happens when I try using a web browser, so it's not just Visual Studio and 
localhost:50000

Anyone know what's going on here? I'm using the latest version of Fidller on Win7 Pro 64-bit, with VS2019.

[Eric R | Senior Technical Support Engineer]

Hi Avrohom Yisroel,

Thank you for providing a detailed explanation. In order to capture WCF Services, there are a couple of steps that need to be completed. See the list below. 

1. Add the following Proxy settings to the WCF Services configuration. This will point it to the Fiddler Proxy Address.

<system.net>
  <defaultProxy>
    <proxy  bypassonlocal="False" usesystemdefault="True" proxyaddress="http://127.0.0.1:8888" />
  </defaultProxy>
</system.net>

2. Add the Show only the following Hosts Filter as shown in the below screenshot.

For additional reference, I have attached a working sample. In order to test the sample, the host port may need to be changed in Fiddler to reflect the updated port of the WCF Services.

Please let me know if you need any additional information. Thank you for using the Fiddler Forums.

Regards,

Eric R | Technical Support Engineer
Progress Telerik