I tested with compiled source from Leap 42.3 and it's working. So I found there are more than 60 patches for the driver and user space tool before moving out from kernel staging. The default usbip tool for 42.3 was too old to v4.4 kernel. I have prepared a testing usbip tool which updated to v2.0. Could you give it a try if possible? Thank you! https://download.opensuse.org/repositories/home:/david_chang:/branches:/openSUSE:/Leap:/42.3:/Update/standard/x86_64/usbip-2.0-28.1.x86_64.rpm