How to capture a server side web api call in fiddler?

Question

I have got the a service with the following topology.

A (Web application) ---calls---> B (Local Web Api) ---calls---> C (Remote Web Api)

I am trying to capture the traffic from B to C in Fiddler, but nothing is logged.

B is a web site hosted locally on my dev box in IIS. It's running on an app pool with a credential other than mine as it has a different set of permissions. Traffic going out from B is not getting logged, even after I have done the following redirect:

<system.net>
<defaultProxy
                enabled = "true"
                useDefaultCredentials = "true">
<proxy autoDetect="false" bypassonlocal="false" proxyaddress="http://127.0.0.1:8888" usesystemdefault="false" />
</defaultProxy>

What can I do to capture traffic leaving B?

Answer 1

The problem is that the .NET Framework is hardcoded to bypass the proxy for localhost addresses. Change the target address to localhost.fiddler and the traffic will be captured.