Comment by pjc50
Plus points for using strace. It's one of those debugging tools everyone know about for emergencies that can't be solved at a higher level, and a great convenience of using Linux. The Windows ETW system is much harder to use, and I'm not sure if it's even possible at all under OSX security.
I have solved an incredible number of problems just by looking at strace output very carefully. Strace combined with Wireshark or Tcpdump are incredible as a toolset for capturing what a program is doing and for capturing what the effect is either on the USB or the NIC.