MAC_DST_FWD
SYS(fail, "ip -netns " NS_DST " neigh add " IP4_TUN_SRC " dev dst lladdr " MAC_DST_FWD);
SYS(fail, "ip -netns " NS_DST " neigh add " IP6_TUN_SRC " dev dst lladdr " MAC_DST_FWD);
"peer name dst_fwd address " MAC_DST_FWD);
SYS(fail, "ip neigh add " IP4_SRC " dev dst lladdr " MAC_DST_FWD);
SYS(fail, "ip neigh add " IP6_SRC " dev dst lladdr " MAC_DST_FWD);