Question: I have an http proxy, which works OK, but there are some address on my lan which provides some web services.

I want to configure my device so that for some range of addresses the proxy is bypassed.

I have tried with 10.0.0.0/8, but it doesn't work!

Answer: 
This doesn't exactly answer your question, but it might help in your use case. 

Maybe you want to have a look at [InputStick](http://inputstick.com). It'll be a USB thumb drive that you pair to Android via Bluetooth. Plugged into a computer it emulates a generic USB HID to send keyboard strokes. An advanced Java API will also allow to specify i.e. device descriptors to emulate non-standard functions. It could provide a nice example that it's defined in software rather than hardware.

For reference, the developer also is working on example programs, such as a Demo Password Manager.
I was searching for something similar and found <https://github.com/pelya/android-keyboard-gadget>. Seems the same thing can be used in your case.

In brief, what I got is you have to write the USB driver in the Android kernel to detect the device as HID.