TCP connection termination (four-way handshake) in Computer Networks - Mini Project: Build & Apply

TCP Connection Termination (Four-Way Handshake)

📖 Scenario: Imagine you are learning how two computers safely end a conversation over the internet using TCP. This process ensures that both computers agree to stop talking without losing any information.

🎯 Goal: You will build a step-by-step outline of the TCP connection termination process, showing the four messages exchanged between two computers to close a connection properly.

📋 What You'll Learn

Create variables representing the four TCP messages with exact names and values

Add a variable to represent the connection state after the first message

Use a sequence of steps to show the four-way handshake messages in order

Complete the process by showing the final connection state after termination

💡 Why This Matters

🌍 Real World

Understanding TCP connection termination helps network engineers and developers ensure reliable and clean disconnections in internet communications.

💼 Career

Knowledge of TCP handshakes is essential for roles in network administration, cybersecurity, and software development involving network programming.

1

Create the initial TCP termination messages

Create four string variables named fin_from_client, ack_from_server, fin_from_server, and ack_from_client with these exact values respectively: "FIN from client", "ACK from server", "FIN from server", and "ACK from client".

Computer Networks

# Your code here

Need a hint?

Use simple string assignments with the exact variable names and values given.

2

Add the initial connection state after client sends FIN

Create a variable called connection_state and set it to the string "FIN_WAIT_1" to represent the state after the client sends the first FIN message.

Computer Networks

fin_from_client = "FIN from client"
ack_from_server = "ACK from server"
fin_from_server = "FIN from server"
ack_from_client = "ACK from client"
# Your code here

Need a hint?

Assign the exact string "FIN_WAIT_1" to the variable connection_state.

3

Outline the four-way handshake message sequence

Create a list called termination_sequence that contains the four variables fin_from_client, ack_from_server, fin_from_server, and ack_from_client in this exact order.

Computer Networks

fin_from_client = "FIN from client"
ack_from_server = "ACK from server"
fin_from_server = "FIN from server"
ack_from_client = "ACK from client"
connection_state = "FIN_WAIT_1"
# Your code here

Need a hint?

Create a list with the four message variables in the exact order shown.

4

Set the final connection state after termination

Update the variable connection_state to the string "CLOSED" to represent the connection state after the four-way handshake completes.

Computer Networks

fin_from_client = "FIN from client"
ack_from_server = "ACK from server"
fin_from_server = "FIN from server"
ack_from_client = "ACK from client"
connection_state = "FIN_WAIT_1"
termination_sequence = [fin_from_client, ack_from_server, fin_from_server, ack_from_client]
# Your code here

Need a hint?

Change the connection_state variable to the exact string "CLOSED".