CCNA协议分析实验--徐曙光.ppt

抓包实验报告
TCP链接建立的三次握手/链接拆除的四次握手
:不安全的原因
Ping第一个慢的原因
QQ端口号抓包
TCP/IP头部
Traceroute所用的协议(思科的命令)
Tracert所用的协议(微软的命令)
作者:徐曙光
A协议分析实验--A协议分析实验--徐曙光
三次握手、四次解除
三次握手
弄好了三次握手把抓到的包关了,又重弄一次,所以前后不一样。。
四次解除
A协议分析实验--A协议分析实验--徐曙光
第一次握手
作者:徐曙光
Client
Server
Client 向Server发起连接请求,
以一个随机初始化seq,
这里seq等于0.
Source port: 49961 (49961)
Destination port: http (80)
[Stream index: 13]
Sequence number: 0 (relative sequence number)
Header length: 28 bytes
Flags: 0x02 (SYN)
000. .... .... = Reserved: Not set
...0 .... .... = Nonce: Not set
.... 0... .... = Congestion Window Reduced (CWR): Not set
.... .0.. .... = ECN-Echo: Not set
.... ..0. .... = Urgent: Not set
.... ...0 .... = Acknowledgement: Not set
.... .... 0... = Push: Not set
.... .... .0.. = Reset: Not set
.... .... ..1. = Syn: Set
看详细数据
第二次握手
SYN(seq=0)
A协议分析实验--A协议分析实验--徐曙光
No. Time Source Destination Protocol Info
8596 TCP 49961 > http [SYN] Seq=0 Win=8192 Len=0 MSS=1460 SACK_PERM=1
Protocol, Src: (), Dst: ()
Version: 4
Header length: 20 bytes
Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
0000 00.. = Differentiated Services Codepoint: Default (0x00)
.... ..0. = ECN-Capable Transport (ECT): 0
.... ...0 = ECN-CE: 0
Total Length: 48
Identification: 0x7acf (31439)
Flags: 0x02 (Don't Fragment)
0... .... = Reserved bit: Not set
.1.. .... = Don't fragment: Set
..0. .... = More fragments: Not set
Fragment offset: 0
Time to live: 128
Protocol: TCP (6)
Header checksum: 0x0000 [incorrect, should be 0x20db]
[Good: False]
[Bad: True]
[Expert Info (Error/Checksum): Bad checksum]
[Message: Bad checksum]
[Severity level: Error]
[Group: Checksum]
Source: ()
Destination: ()
Transmission Control Protocol, Src Port: 49961 (49961), Dst Port: http (80), Seq: 0, Len: 0
Source port: 49961 (49961)
Destination port: http (80)