/usr/include/libnl3/netlink/route/ is in libnl-3-dev 3.2.21-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/libnl3/netlink/route/addr.h
/usr/include/libnl3/netlink/route/class.h
/usr/include/libnl3/netlink/route/classifier.h
/usr/include/libnl3/netlink/route/cls/
/usr/include/libnl3/netlink/route/cls/basic.h
/usr/include/libnl3/netlink/route/cls/cgroup.h
/usr/include/libnl3/netlink/route/cls/ematch/
/usr/include/libnl3/netlink/route/cls/ematch.h
/usr/include/libnl3/netlink/route/cls/ematch/cmp.h
/usr/include/libnl3/netlink/route/cls/ematch/meta.h
/usr/include/libnl3/netlink/route/cls/ematch/nbyte.h
/usr/include/libnl3/netlink/route/cls/ematch/text.h
/usr/include/libnl3/netlink/route/cls/fw.h
/usr/include/libnl3/netlink/route/cls/police.h
/usr/include/libnl3/netlink/route/cls/u32.h
/usr/include/libnl3/netlink/route/link/
/usr/include/libnl3/netlink/route/link.h
/usr/include/libnl3/netlink/route/link/api.h
/usr/include/libnl3/netlink/route/link/bonding.h
/usr/include/libnl3/netlink/route/link/can.h
/usr/include/libnl3/netlink/route/link/inet.h
/usr/include/libnl3/netlink/route/link/info-api.h
/usr/include/libnl3/netlink/route/link/vlan.h
/usr/include/libnl3/netlink/route/neighbour.h
/usr/include/libnl3/netlink/route/neightbl.h
/usr/include/libnl3/netlink/route/nexthop.h
/usr/include/libnl3/netlink/route/pktloc.h
/usr/include/libnl3/netlink/route/qdisc/
/usr/include/libnl3/netlink/route/qdisc.h
/usr/include/libnl3/netlink/route/qdisc/cbq.h
/usr/include/libnl3/netlink/route/qdisc/dsmark.h
/usr/include/libnl3/netlink/route/qdisc/fifo.h
/usr/include/libnl3/netlink/route/qdisc/htb.h
/usr/include/libnl3/netlink/route/qdisc/netem.h
/usr/include/libnl3/netlink/route/qdisc/plug.h
/usr/include/libnl3/netlink/route/qdisc/prio.h
/usr/include/libnl3/netlink/route/qdisc/red.h
/usr/include/libnl3/netlink/route/qdisc/sfq.h
/usr/include/libnl3/netlink/route/qdisc/tbf.h
/usr/include/libnl3/netlink/route/route.h
/usr/include/libnl3/netlink/route/rtnl.h
/usr/include/libnl3/netlink/route/rule.h
/usr/include/libnl3/netlink/route/tc-api.h
/usr/include/libnl3/netlink/route/tc.h