tapinfo
struct tapinfo tapinfo;
if (ioctl(fd, TAPGIFINFO, &tapinfo) < 0) {
ifp->if_mtu = tapinfo.mtu;
ifp->if_baudrate = tapinfo.baudrate;
struct tapinfo *tapp = NULL;
tapp = (struct tapinfo *)data;
tapp = (struct tapinfo *)data;
#define TAPSIFINFO _IOW('t', 91, struct tapinfo)
#define TAPGIFINFO _IOR('t', 92, struct tapinfo)