三次握⼿建⽴连接（SYN标志）
*此篇博客仅作为个⼈笔记和学习参考
三次握⼿建⽴连接(SYN标志)
客户端发送链接请求，此时处于等待确认状态；服务端收到请求，回应确认请求；最后客户端确认；建⽴完毕，开始传输数据！
副部级高校
四次握⼿断开连接(FIN标志)
客户端发送断开请求，此时处于等待确认状态；服务端收到请求，回应确认请求，并再次确认是否断开；客户端最后确认；断开链接！TCP协议包⾸部格式结婚大作战主题曲
三次握⼿建⽴连接---分析
第⼀次握⼿(SYN)
Transmission Control Protocol, Src Port: 52777 (52777), Dst Port: http (80), Seq: 0, Len: 0
#TCP，源端⼝:52777,⽬标端⼝:80#
Source Port: 52777 (52777) #源端⼝#
Destination Port: http (80) #⽬标端⼝#
[Stream index: 1] #流节点号#
Sequence number: 0 (relative quence number) #序列号#
Acknowledgment number: 0 #确认编号#
Header Length: 32 bytes #⾸部长度#
Flags: 0x002 (SYN) #标志#
1. .... .... = Rerved: Not t
...0 .... .... = Nonce: Not t
.... 0... .... = Congestion Window Reduced (CWR): Not t
.... .0.. .... = ECN-Echo: Not t
.
... ..0. .... = Urgent: Not t #紧急指针#
.... ...0 .... = Acknowledgment: Not t #确认编号#
.... .... 0... = Push: Not t #紧急位#
.... .... .0.. = Ret: Not t #重置#
.... .... ..1. = Syn: Set #SYN标志位#
[Expert Info (Chat/Sequence): Connection establish request (SYN): rver port 80] #专家信息#
[Connection establish request (SYN): rver port 80] #消息#
[Severity level: Chat] #安全级别#
[Group: Sequence] #组#
.... .... ...0 = Fin: Not t #FIN标志位#
Window size value: 8192 #窗⼝⼤⼩#
[Calculated window size: 8192] #估计的窗⼝⼤⼩#
Checksum: 0x0a48 [unverified] #校验和#
Urgent pointer: 0 #紧急指针#
Options: (12 bytes), Maximum gment size, No-Operation (NOP), Window scale, No-Operation (NOP), No-Operation (NOP), SACK permitted #选项#
Maximum gment size: 1460 bytes #最⼤段⼤⼩#
distinctly
No-Operation (NOP) #⽆操作指令#
No-Operation (NOP) #⽆操作指令#
No-Operation (NOP) #⽆操作指令#
TCP SACK Permitted Option: True #TCP SACK允许选项#
第⼆次握⼿(SYN/ACK)
Transmission Control Protocol, Src Port: http (80), Dst Port: 52777 (52777), Seq: 0, Ack: 1, Len: 0 #TCP，源端⼝:80,⽬标端⼝:52777#
Source Port: http (80) #源端⼝#
Destination Port: 52777 (52777) #⽬标端⼝#
[Stream index: 1] #流节点号#
Sequence number: 0 (relative quence number) #序列号#
Acknowledgment number: 1 (relative ack number) #确认编号#
Header Length: 32 bytes #⾸部长度#
Flags: 0x012 (SYN, ACK) #标志#
2. .... .... = Rerved: Not t
...0 .... .... = Nonce: Not t
.... 0... .... = Congestion Window Reduced (CWR): Not t
.... .0.. .... = ECN-Echo: Not t
.... ..0. .... = Urgent: Not t #紧急指针#
英语评课稿.... ...1 .... = Acknowledgment: Not t #确认编号#
.... .... 0... = Push: Not t #紧急位#
.... .... .0.. = Ret: Not t #重置#在线词语字典
.... .... ..1. = Syn: Set #SYN标志位#
[Expert Info (Chat/Sequence): Connection establish request (SYN): rver port 80] #专家信息#
[Connection establish request (SYN): rver port 80] #消息#
[Severity level: Chat] #安全级别#
[Group: Sequence] #组#
.... .... ...0 = Fin: Not t #FIN标志位#
Window size value: 8192 #窗⼝⼤⼩#
[Calculated window size: 8192] #估计的窗⼝⼤⼩#
Checksum: 0x0a48 [unverified] #校验和#
Urgent pointer: 0 #紧急指针#
Options: (12 bytes), Maximum gment size, No-Operation (NOP), Window scale, No-Operation (NOP), No-Operation (NOP), SACK permitted #选项#
Maximum gment size: 1460 bytes #最⼤段⼤⼩#
No-Operation (NOP) #⽆操作指令#
No-Operation (NOP) #⽆操作指令#
No-Operation (NOP) #⽆操作指令#
TCP SACK Permitted Option: True #TCP SACK允许选项#
[SEQ/ACK analysis] #序列号 确认编号分析#
[This is an ACK to the gment in frame: 4]
[The RTT to ACK the gment was: 0.170392000 conds]
[iRTT: 0.170478000 conds]
第三次握⼿(ACK)
Transmission Control Protocol, Src Port: 52777 (52777), Dst Port: http (80), Seq: 1, Ack: 1, Len: 0 #TCP，源端⼝:52777,⽬标端⼝:80#
Source Port: 52777 (52777) #源端⼝#
Destination Port: http (80) #⽬标端⼝#
[Stream index: 1] #流节点号#
Sequence number: 0 (relative quence number) #序列号#
Acknowledgment number: 0 #确认编号#
Header Length: 32 bytes #⾸部长度#
Flags: 0x010 (ACK) #标志#
3. .... .... = Rerved: Not t
...0 .... .... = Nonce: Not t英语chant
.... 0... .... = Congestion Window Reduced (CWR): Not t
.... .0.. .... = ECN-Echo: Not t
口才练习.... .0.. .... = ECN-Echo: Not t
.... ..0. .... = Urgent: Not t #紧急指针#
.... ...1 .... = Acknowledgment: Not t #确认编号#
.... .... 0... = Push: Not t #紧急位#
.... .... .0.. = Ret: Not t #重置#
.... .... ..0. = Syn: Set #SYN标志位#
[Expert Info (Chat/Sequence): Connection establish request (SYN): rver port 80] #专家信息#
found
[Connection establish request (SYN): rver port 80] #消息#
[Severity level: Chat] #安全级别#
[Group: Sequence] #组#
.... .... ...0 = Fin: Not t #FIN标志位#
2012年考研政治
Window size value: 8192 #窗⼝⼤⼩#
[Calculated window size: 8192] #估计的窗⼝⼤⼩#
Checksum: 0x0a48 [unverified] #校验和#
Urgent pointer: 0 #紧急指针#
Options: (12 bytes), Maximum gment size, No-Operation (NOP), Window scale, No-Operation (NOP), No-Operation (NOP), SACK permitted #选项#
Maximum gment size: 1460 bytes #最⼤段⼤⼩#
No-Operation (NOP) #⽆操作指令#
No-Operation (NOP) #⽆操作指令#
No-Operation (NOP) #⽆操作指令#
TCP SACK Permitted Option: True #TCP SACK允许选项#
[SEQ/ACK analysis] #序列号 确认编号分析#
[This is an ACK to the gment in frame: 13]
[The RTT to ACK the gment was: 0.000061000 conds]
[iRTT: 0.168388000 conds]
四次握⼿断开连接---分析
基本同上，SYN变成FIN，值为1；
Flags: 0x011 (FIN, ACK)
1. .... .... = Rerved: Not t
...0 .... .... = Nonce: Not t
.... 0... .... = Congestion Window Reduced (CWR): Not t
.... .0.. .... = ECN-Echo: Not t
.... ..0. .... = Urgent: Not t
.... ...1 .... = Acknowledgment: Set
.... .... 0... = Push: Not t
.... .... .0.. = Ret: Not t
.... .... ..0. = Syn: Not t
.... .... ...1 = Fin: Set
TCP重置---分析
郑州会计基本同上，SYN变成RST，值为1；
Flags: 0x014 (RST, ACK)
1. .... .... = Rerved: Not t
...0 .... .... = Nonce: Not t
.... 0... .... = Congestion Window Reduced (CWR): Not t
.... .0.. .... = ECN-Echo: Not t
.... ..0. .... = Urgent: Not t
.... ...1 .... = Acknowledgment: Set
.... .... 0... = Push: Not t
.... .... .1.. = Ret: Set
