/usr/include/CGAL/Nef_2/ is in libcgal-dev 4.7-4.
This file is owned by root:root, with mode 0o755.
..
/usr/include/CGAL/Nef_2/Bounding_box_2.h
/usr/include/CGAL/Nef_2/Constrained_triang_traits.h
/usr/include/CGAL/Nef_2/HDS_items.h
/usr/include/CGAL/Nef_2/Line_to_epoint.h
/usr/include/CGAL/Nef_2/Object_handle.h
/usr/include/CGAL/Nef_2/Object_index.h
/usr/include/CGAL/Nef_2/PM_checker.h
/usr/include/CGAL/Nef_2/PM_const_decorator.h
/usr/include/CGAL/Nef_2/PM_decorator.h
/usr/include/CGAL/Nef_2/PM_explorer.h
/usr/include/CGAL/Nef_2/PM_io_parser.h
/usr/include/CGAL/Nef_2/PM_overlayer.h
/usr/include/CGAL/Nef_2/PM_persistent_PL.h
/usr/include/CGAL/Nef_2/PM_point_locator.h
/usr/include/CGAL/Nef_2/Polynomial.h
/usr/include/CGAL/Nef_2/Segment_overlay_traits.h
/usr/include/CGAL/Nef_2/debug.h
/usr/include/CGAL/Nef_2/gen_point_location.h
/usr/include/CGAL/Nef_2/geninfo.h
/usr/include/CGAL/Nef_2/iterator_tools.h