Intercepting localhost traffic from ASP.NET Core 1.0 on Windows 10

Question

I've been trying to intercept localhost traffic for ASP.NET Core 1.0 using Fiddler and Wireshark but neither have been working. I've looked all over SO for an answer but none of the answers have worked.

Here is a list of the solutions I have already tried:

-Changing localhost to localhost.fiddler

-Turning on 'Use PAC Script'

-Changing 'localhost' to the PC hostname

-Changing 'localhost' to 'localhost.'

-Deleting '<-loopback>;' from Tools -> Fiddler Options -> Connections -> 'ByPass Fiddler for URLs that start with:', however, the option does not stay deleted after saving the options. (When I go back to fiddler options, '<-loopback>' is still there)

-Deleting '<-loopback>;' from Tools -> WinINET options -> Connections -> LAN settings -> Advanced

I am using Fiddler v4.6.3.44034, Windows 10, Visual Studio 2015 running ASP.NET core 1.0. Any help would be appreciated.

Answer 1

Have you tried MS Message Analyzer? You need to setup Message Analyzer to track the loopback adapter. It works well for tracking traffic between IIS (localhost) and Kestrel.

Answer 2

As Nate alluded to, if you're trying to intercept calls to the ASP.NET Core application itself (e.g from a running test suite) and are using TestHost, David Fowler mentions it's just running in memory and not actually called over the network. See his response in GitHub issue filed here.