Third job: Packet Tracer analysis using TCP connection establishment

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• Name: Wong Choi Chak
• Student ID: 201821121014　　
• Class: calculated 1811

1 Purpose

• Using different network router
• Use the command line router
• By grabbing HTTP packets, TCP connection establishment process analysis

2 Experimental content

Use Packet Tracer, properly configure the network parameters, by crawling HTTP packets, analyzes the TCP connection establishment procedure.

• Establish a network topology
• Configuration parameters
• Ethereal
• Analysis of the data packet

3. The test report

3.1 Establish a network topology

Network topology as shown below:

 

3.2 Configuration Parameters

• IP address of the client is192.168.1.14

• IP address of the server is192.168.1.14

• Configuring Routing:

3.3 capture, analyze TCP connection establishment

(1) Draw a schematic view of a TCP connection

As shown below:

　　

 

 

(2) Change in number and acknowledgment number

　　ack seq equal to the first time when the second handshake handshake, ack seq equal when the first handshake; when the ack seq third handshake at second handshake, ack seq equal to the second

(3) Q & A: Why we need a third connection establishment handshake

 　　Failure to prevent the connection request message is received by the server segment, resulting in an error. If only two-way handshake to establish a connection, the client has not changed much, still need to get the server's response before entering ESTABLISHED state, while the server into the ESTABLISHED state after the connection request is received.