- Name: Frankie Lam
- Student ID: 201821121041
- Class: calculated 1812
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
3.2 Configuration Parameters
Command interpreter:
enable: enter the privileged EXEC mode
configure terminal: Enter the global configuration mode
interface + Interface Name: Select the appropriate router interface
p address: ip address configuration for the interface
no shutdown: Activation Interfaces
3.3 capture, analyze TCP connection establishment
TCP connection 1. Draw a schematic diagram of the TCP connection establishment
- 2. Analysis of changes in numbers and acknowledgment numbers
- The first handshake: a client first creates a transmission control module, a TCP connection is established; in this case the header sync bit SYN = 1, while selecting an initial sequence number seq = x
- Second handshake: confirmation packet sent by the server to the client, the SYN and ACK bits are set to 1-bit acknowledgment number is ack = x + 1, and also choose an initial sequence number for itself seq = y
- Third handshake: the client subject to confirmation message, but also to respond to the server; ACK set to 1, confirm the number ack = y + 1, and their number seq = x + 1
- 3. Answer: Why we need a third connection establishment handshake
- In order to prevent the connection request has failed segment server suddenly spread, resulting in an error.