nmport_open_desc
int nmport_open_desc(struct nmport_d *d);
if (nmport_open_desc(d) < 0)
if (nmport_open_desc(rxport->nmd) < 0) {
if (nmport_open_desc(t->nmd) < 0) {
if (nmport_open_desc(g.nmd) < 0)