BEWARE! There are such adapters that do exactly that, they use RJ45 patchcables with a large number of adapters RJ45-F<->$RANDOM to build all sorts of cables and adapters, e.g. micro-USB-M<--(patchcable)-->USB-A-F. NEVER EVER use such a thing to connect N900-USB directly to a ethernet network or NIC. It will definitely fry your N900 /j