Why doesn't Fiddler see my web services traffic?

Question

I had a problem that Fiddler did not show my web services calls made from my application (executed locally). I found and solved my problem.

So my question is not, but why doesn't Fiddler show web service traffic? I have a very limited understanding of how network traffic works, so it can be pretty simple / obvious. All I can decrypt is:

• I don’t think this has anything to do with HTTPS, since I see HTTPS requests in Fiddler (decoded if I want using the Fiddler settings).

• I copied the code snippet new WebProxy("127.0.0.1", 8888); to make it work, so should it have something to do with proxies?

This is an ASP.NET application, if it matters.

Answer 1

Really old question, but:

Although the answer and comments hint at a correct solution, they are far from answering the question.

Fiddler sees traffic with your user account. Because web services are managed by the application pool identifier, the violinist cannot see his traffic.

The simplest solution (and the only thing that worked for me) is to change the website application pool user to run under your account

Just:

• Open IIS
• Find the name of the website’s application pool (right click on the website → Site Management → Advanced Settings → List in the application pool)
• Go to the advanced settings of the application pool (application pools → Right-click the desired application pool → Advanced settings)
• Change the user account to your account (Identity → ... → Custom Account → Set)

Answer 2

As noted above:

This first paragraph was just an explanation that I needed: when Fiddler starts and joins, it configures the current user proxy settings for Fiddler, which defaults to 127.0.0.1:8888. This means that traffic from most applications automatically flows through Fiddler without any additional configuration steps. Although, I think I should also thank Eric, as he seems to be the one who wrote it!

References

• Capturing traffic for .Net services using Fiddler

Answer 3

adding the following contents inside the config is also a solution.

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

Also, if the web service traffic points to another application in the same local host, try using the machine name instead of localhost in the request URL.