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.
It's now >six
years later and
somewhere in between someone created the [Keepass2 USB Keyboard
Plugin](https://duckduckgo.com/?q=Keepass2%20USB%20Keyboard) for [Keepass2Android](https://play.google.com/store/apps/details?id=keepass2android.keepass2android).

Wanted to add this
information here for the sake of completeness and because I found
this question *unanswered* and the aforementioned plugin while
searching for exactly something like that.

I haven't tested it myself yet...