Is it possible to use Fiddler to debug Http traffic issue?

Question

Hello everyone,

I am using ASP.Net + .Net 3.5 + VSTS 2008 + IIS 7.0 + C# to develop a web application. I want to use Fiddler to debug (i.e. monitor request and response Http traffic) local traffic -- i.e. when I test web application inside VSTS 2008's built-in test ASP.Net web server. Is that feasible? If yes, how to monitor such traffic? For example, in VSTS 2008's built-in ASP.Net test web application server, the Url I want to monitor request traffic sent to http://localhost:1870/Default.aspx and its response (i.e. when F5 is pressed in VSTS 2008).

BTW: I previously think Fiddler could only be used to monitor port 80 Http traffic, not sure whether port 1870 could be monitored?

thanks in advance, George

Answer 1

Have you tried adding a dot after the localhost? Quick test on my machine seems to indicate this is needed in IE but might not be in Firefox actually.

Answer 2

Doesn't fiddler ignore 'Localhost' try changing the url's to your machines hostname.

Answer 3

If you change your URL to 'http://ipv4.fiddler:1870/..' instead of 'http://localhost:1870/...' then fiddler will intercept your traffic and display the requests. Localhost doesn't go through wininet (I believe) which fiddler will then ignore. Fiddler registers ipv4.fiddler as localhost so you can monitor local traffic.

You can also add an entry to your hosts file and direct some URL (e.g. mysite.com 127.0.0.1) and use it as your URL (e.g. http://mysite.com:1870/...) and fiddler will pick that up, too.