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How to put a breakpoint in a request sent through Fiddler?


In fiddler, how to terminate the request in between before it reaches the host. For eg I send a request and I want to put a breakpoint in that request so that I'm not able to receive the response. Basically, I want to inspect the response before it is returned to the original caller and how my service is behaving if there's a connection lost or some other termination by which the request was unable to reach the server. Any answer is highly appreciated. Sorry for any flaw, I'm a newbie in using Fiddler. :)


Solution

  • Fiddler offers several mechanisms for interfering with requests. If your goal is to simply kill the request without returning a response, you can create a rule with an Action of *drop or *reset rules in Fiddler's AutoResponder.

    *drop will close the client connection immediately without sending a response. The closure is graceful at the TCP/IP level, returning a FIN to the client.

    *reset will close the client connection immediately without sending a response. The closure is abrupt at the TCP/IP level, returning a RST to the client.

    Alternatively, you can have Fiddler return any HTTP/4xx or HTTP/5xx to the client.

    Lastly, you could use a breakpoint to allow you to manually manipulate the request before it's sent to the server, and/or manipulate the server's response before it's sent to the client. Use the bpu command in the QuickExec box to break on a given URL (e.g. bpu sample.asp).