/usr/lib/x86_64-linux-gnu/libjack.so.0 is in libjack0 1:0.124.1+20140122git5013bed0-3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libjack.so.0.0.28
/usr/lib/x86_64-linux-gnu/libjack.so.0.0.28