Fiddler: Can I redirect outgoing traffic from foreign console app to Fiddler instance (localhost:8888)?

Question

I am looking for a way to forward traffic from an application which goes to the web over port 443 to an instance of Fiddler running on my computer. Fiddler does not see this traffic while a packet trace application verified that the traffic is going out.

The application is foreign and I am not able to modify how it requests and it is not going through Internet Explorer (or apparently any other browser). If this app is going to an ip address (ie. 66.xxx.xx.xx port 443) or to a named host (ie. https://www.anysite.com), is there a way to tell my computer to forward this traffic to Fiddler, ie. to localhost port 8888?

I am not sure I am using the right terminology to describe this but and ideas would be appreciated!

Thanks,

David

Answer 1

If you can't get the application itself to send traffic to localhost on a specified port, then you need something lower level than Fiddler. Try WireShark.

http://www.wireshark.com/

Answer 2

@David: What's the application in question? Virtually all applications can be proxied, because those that can't aren't usable from most corporate networks. In some cases, you have to make minor changes to the environment (e.g. setting the proxy for the JVM). Some details are here: http://www.fiddler2.com/fiddler/help/hookup.asp

Using Netmon or Wireshark, you should be able to determine whether or not the application in question is making a request directly to a fixed IP address, or more likely, doing a DNS lookup first. If it's doing a DNS lookup first, you could edit your Windows Hosts file so that whateverthehostis.com points at 127.0.0.1. Because the hosts file only maps host to IP and not port to port, you'll need to adjust Fiddler to run on the target port that the application is looking for (use Tools > Fiddler Options for that).

Now, if the traffic is HTTPS (and I'm guessing it is) you're going to have a problem at that point, because Fiddler currently can only act as a HTTPS endpoint when it "knows" that the traffic is HTTPS by virtue of the client having opened a CONNECT tunnel first. This is something that could be adjusted in a future version of Fiddler, but it's not a common request.