TCP Packet Simulation Lab

This lab gives beginners a hands-on experience with how TCP packets move through a network, simulating every step from the initial handshake to the final data delivery. Through a visual interface, learners observe how devices communicate using TCP, how the network handles routing, and what it looks like when a connection is successfully established.

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Lab Objective

“Deploy the static site attached to this task. Send a TCP packet from Computer1 to Computer3. The simulator will break down every step a packet takes to travel across the network. A flag is revealed once the process is complete.”

Your goal: Use the network simulator to understand how TCP packets travel and identify the full sequence of handshake and delivery.

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Interactive Scenario Walkthrough

Lab Environment

• Web-based static lab interface

• Devices: Computer1, Computer2, Computer3, Router

• Packet types: TCP (handshake steps visualized)

• Packet log: Displays each network interaction in sequence

• Browser: Works best on Chrome or Firefox

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Task Breakdown

• Deploy the static site

• Send a TCP packet from Computer1 to Computer3

• Observe the sequence of ARP, routing, and TCP handshakes

• Identify how many TCP handshake entries appear

• Capture the final flag once the packet is delivered

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Action Taken

After launching the simulator, I selected:

• Source: Computer1

• Destination: Computer3

• Packet Type: TCP

Upon sending the packet, the simulator began logging each step:

• ARP request and reply for address resolution

• Routing steps via the router

• Three-way TCP handshake (SYN, SYN-ACK, ACK)

• Final data transmission and response

In total, five entries related to the TCP handshake were recorded, marking each critical stage of establishing a reliable connection.

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Outcome

Once the TCP connection was successfully established and data delivered to Computer3, the system displayed the flag:

makefileCopyEditFlag: THM{YOU'VE_GOT_DATA}

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Key Concept: What is a TCP Handshake?

The TCP handshake is a three-step process (SYN → SYN-ACK → ACK) used to establish a reliable connection between two devices. In this simulation:

• You observe how devices locate each other (ARP)

• How packets are routed through the network

• And how reliable communication is ensured before sending data

This builds a foundational understanding of how networked systems connect — a critical skill for any aspiring cybersecurity or network professional.

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Skills Practiced

• TCP communication process

• Reading and analyzing network logs

• Understanding routing and ARP behavior

• Recognizing handshake steps in live scenarios

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Flag Captured

THM{YOU'VE_GOT_DATA}

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Final Thoughts

This lab is a practical simulation of TCP communication, helping learners visualize the abstract flow of packets across a network. It reinforces the importance of the TCP handshake and routing, and serves as a gateway to understanding packet inspection, network troubleshooting, and secure communication.