Capturing ASP.Net Server Traffic in Fiddler, Charles or Burp

Hackered
Friday, May 9, 2014
by Sean McAlinden

As client calls made from an ASP.Net application are not captured by the mentioned tools by default, you need to configure you application to point to their corresponding proxy address.   Whilst this can be done in code, an easy solution is to add the following to your web.config file.

<configuration>
  <system.net>
    <defaultproxy>
      <proxy proxyaddress="http://127.0.0.1:8080" bypassonlocal="True" usesystemdefault="False" />
    </defaultproxy>
  </system.net>
</configuration>

In some applications (like Fiddler) you need to configure it to capture all processes. In fiddler this is done on the footer bar however it is normally enabled by default.