Connecting Devices to Fiddler Without Proxy Changing?

Question

I'm interested in using Fiddler to inspect HTTP(S) API traffic on my home network. I want two networks/routers; "Normal" and "Fiddler". I want the devices to easily connect to either network. I do not want to manually configure/unconfigure proxy settings when moving devices between normal and Fiddler proxy network. I just want to select a new access point and have the device work. How can this be done? Will some kind of port-forwarding on the "fiddler" router suffice?

Answer 1

After several weeks of experimentation and discussion, my conclusion is that neither Fiddler nor Charles Proxy support transparent proxy which is key to making a simple router setup work. OTOH, mitmproxy does work well. mitmproxy runs on OS/X and Linux. For Windows there are two options, mitmdump is a UI-less version of mitmproxy, and mitmweb (available but not presently released) has a very promising UI.

Indeed you easily configure a router to gateway to a mitm system. From there mitm will show http requests and responses. If you want to see HTTPS, you'll simply need to have the device accept an mitm certificate. Do so by visiting the special domain name http://mitm.it and follow instructions.

For a more detailed discussion see Best Way to Inspect HTTP(S) APIs of Many Devices

I wrote up the procedure for configuring a router to proxy client traffic to a transparent proxy. Works great with MitmProxy. The beauty of this approach is that you can simply connect a client device, wired or wireless, to the router and HTTP(S) traffic will be displayed by MitmProxy. No need to fiddle with each device's proxy settings. You simply choose the router's network, when done you flip back to the usual router.

Best Way to Inspect HTTP(S) API Traffic in a Multi-Platform Multi-Device Environment