/usr/lib/linux-tools/4.13.0-31-generic/usbip is in linux-tools-4.13.0-31-generic 4.13.0-31.34~16.04.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/linux-tools/4.13.0-31-generic/../../linux-hwe-tools-4.13.0-31/usbip