/usr/lib/x86_64-linux-gnu/libnss_gns4.so is in gnunet-dev 0.10.1-4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /lib/x86_64-linux-gnu/libnss_gns4.so.2
/lib/x86_64-linux-gnu/libnss_gns4.so.2