IFF_FWD_IPV6
if ((oflags & (IFF_NAT_T|IFF_FWD_IPV6)) ==
(ifp->if_flags & (IFF_NAT_T|IFF_FWD_IPV6)))
sc->ipsec_if.if_flags |= IFF_FWD_IPV6;
return (sc->ipsec_if.if_flags & IFF_FWD_IPV6) != 0;