TCP協議三次握手數據包交互:
1、SYN:
2、SYN+ACK:
3、ACK:
數據包字段詳解:
確認標識ACK繼承序列號SEQ數字,並+1-隱含確認機制;
Source Port:源端口,16bit;
Destination Port:目的端口,16bit;
Sequence number:序列號,32bit;
Acknowledgment number:確認號,32bit;
Header Length:頭部長度,4bit;
Flags:標識位;
- Reserved:保留字段;
- Nonce
- Congestion Window Reduced:擁塞窗口減少;
- ECN-Echo:顯式擁塞提醒迴應;
- Urgent:緊急指針位;
- Acknowledgment:應答位;
- Push:推送位,數據包立即發送;
- Reset:復位,中斷某個會話;
- Syn:同步會話,會話開始標誌;
- Fin:結束會話,會話結束標誌;
Window size value:窗口大小,16bit;
Checksum:校驗和,16bit;