IPN_NOTDST
nat->in_flags |= IPN_NOTDST;
nat->in_flags |= IPN_NOTDST;
if (np->in_flags & IPN_NOTDST)
n->in_flags &= ~IPN_NOTDST;
match ^= ((np->in_flags & IPN_NOTDST) != 0);
IPN_ROUNDR|IPN_FILTER|IPN_NOTSRC|IPN_NOTDST|IPN_NO|\
match ^= ((np->in_flags & IPN_NOTDST) != 0);