usbredir is a protocol for redirecting USB traffic from a single USB device,
to a different (virtual) machine than the one to which the USB device is
attached. See usb-redirection-protocol.txt for the description / definition
of this protocol.

With the official 0.3 release the protocol is now frozen (only extensions
advertised through capabilities can be added from now on).

WWW: http://cgit.freedesktop.org/spice/usbredir