/usr/include/CGAL/Nef_3/ is in libcgal-dev 4.2-5ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/CGAL/Nef_3/Binary_operation.h
/usr/include/CGAL/Nef_3/Bounding_box_3.h
/usr/include/CGAL/Nef_3/Combine_with_halfspace.h
/usr/include/CGAL/Nef_3/Default_items.h
/usr/include/CGAL/Nef_3/Edge_edge_overlay.h
/usr/include/CGAL/Nef_3/Exact_triangulation_euclidean_traits_xy_3.h
/usr/include/CGAL/Nef_3/Exact_triangulation_euclidean_traits_xz_3.h
/usr/include/CGAL/Nef_3/Exact_triangulation_euclidean_traits_yz_3.h
/usr/include/CGAL/Nef_3/Halfedge.h
/usr/include/CGAL/Nef_3/Halffacet.h
/usr/include/CGAL/Nef_3/ID_support_handler.h
/usr/include/CGAL/Nef_3/Infimaximal_box.h
/usr/include/CGAL/Nef_3/K3_tree.h
/usr/include/CGAL/Nef_3/Mark_bounded_volumes.h
/usr/include/CGAL/Nef_3/Nef_box.h
/usr/include/CGAL/Nef_3/OGL_helper.h
/usr/include/CGAL/Nef_3/Pluecker_line_3.h
/usr/include/CGAL/Nef_3/SFace.h
/usr/include/CGAL/Nef_3/SHalfedge.h
/usr/include/CGAL/Nef_3/SHalfloop.h
/usr/include/CGAL/Nef_3/SM_visualizor.h
/usr/include/CGAL/Nef_3/SNC_FM_decorator.h
/usr/include/CGAL/Nef_3/SNC_SM_explorer.h
/usr/include/CGAL/Nef_3/SNC_SM_overlayer.h
/usr/include/CGAL/Nef_3/SNC_SM_visualizor.h
/usr/include/CGAL/Nef_3/SNC_const_decorator.h
/usr/include/CGAL/Nef_3/SNC_constructor.h
/usr/include/CGAL/Nef_3/SNC_decorator.h
/usr/include/CGAL/Nef_3/SNC_decorator_traits.h
/usr/include/CGAL/Nef_3/SNC_external_structure.h
/usr/include/CGAL/Nef_3/SNC_indexed_items.h
/usr/include/CGAL/Nef_3/SNC_intersection.h
/usr/include/CGAL/Nef_3/SNC_io_parser.h
/usr/include/CGAL/Nef_3/SNC_items.h
/usr/include/CGAL/Nef_3/SNC_iteration.h
/usr/include/CGAL/Nef_3/SNC_k3_tree_traits.h
/usr/include/CGAL/Nef_3/SNC_list.h
/usr/include/CGAL/Nef_3/SNC_point_locator.h
/usr/include/CGAL/Nef_3/SNC_ray_shooter.h
/usr/include/CGAL/Nef_3/SNC_simplify.h
/usr/include/CGAL/Nef_3/SNC_sphere_map.h
/usr/include/CGAL/Nef_3/SNC_structure.h
/usr/include/CGAL/Nef_3/Vertex.h
/usr/include/CGAL/Nef_3/Volume.h
/usr/include/CGAL/Nef_3/binop_intersection_tests.h
/usr/include/CGAL/Nef_3/bounded_side_3.h
/usr/include/CGAL/Nef_3/polyhedron_3_to_nef_3.h
/usr/include/CGAL/Nef_3/quotient_coordinates_to_homogeneous_point.h
/usr/include/CGAL/Nef_3/shell_to_nef_3.h
/usr/include/CGAL/Nef_3/vertex_cycle_to_nef_3.h