DLT_LOOP          209 net/if_loop.c  	bpfattach(&ifp->if_bpf, ifp, DLT_LOOP, sizeof(u_int32_t));
DLT_LOOP          206 net/if_tun.c   		bpfattach(&ifp->if_bpf, ifp, DLT_LOOP, sizeof(u_int32_t));