PFIL_TYPE_IFNET
if_pfil = pfil_head_create(PFIL_TYPE_IFNET, NULL);
ifp->if_pfil = pfil_head_create(PFIL_TYPE_IFNET, ifp);
if ((npf_ph_ether = pfil_head_get(PFIL_TYPE_IFNET, ifp)) == NULL) {
npf_ph_if = pfil_head_get(PFIL_TYPE_IFNET, 0);