struct tcphdr

struct tcphdr {
	uint16_t th_sport;
	uint16_t th_dport;
	uint32_t th_seq;
	uint32_t th_ack;
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
	uint8_t th_off:4;
	uint8_t _padding0:4;
#else
	uint8_t th_off:4;
	uint8_t _padding0:4;
#endif
	uint8_t th_flags;
	uint16_t th_win;
	uint16_t th_sum;
	uint16_t th_urp;
};