/usr/lib/x86_64-linux-gnu/libSDL_net.so is in libsdl-net1.2-dev 1.2.8-4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libSDL_net-1.2.so.0.8.0
/usr/lib/x86_64-linux-gnu/libSDL_net-1.2.so.0.8.0