TCP/IP Stack Demonstration

An Object-Oriented Pyhton demonstration of how the TCP/IP Stack functions

Intro • Run it • Use it

Introduction

This is a client / server practical demonstration of the functionality of the TCP / IP Stack written in Python. The project aims to demonstrate in a visual manner the encapsulation process of packets thoughout the stack. Some the project's functions can also be individually invoked from the Client application.

This project was made for a presentation about the TCP / IP Stack during college.

How to Run it

To run the application, first run the server, then on a different terminal the client application, in the following manner:

Server Terminal:

cd Stack
python3 server.py

Client Terminal:

cd Stack
python3 client.py

If examining the Server application is not necessary, it can also be run on the background, facilitating execution

Client & Server (single terminal):

cd Stack
python3 server.py &
python3 client.py

Dependencies:

This project depends on python3 and the following python libraries: socket pickle

How to Use it

Once the client & server applications have connected, input your commands on the client application. The main function is the stack command, which simulates visually the encapsulation process of the TCP / IP Stack, while the handshake command simulates visually the TCP handshake process.

The help command prints all available commands on the terminal screen. A single message can also be sent to the server application via sockets by simply typing it and pressing enter.

Manual / Documentation

Client

Click to read

Name

Client - An object oriented Client application that sends messages to the Server application.

Description

Client is an object oriented Client application written in Python that sends messages to the Server application. The Client can send regular messages or commands.

Said commands can be a Ping, which asks for the Server application IP address; a Handshake, which utilizes messages to simulate / demonstrate the TCP Three-Way Handshake process; or Stack which simulates the TCP/IP Stack encapsulation and sending process.

The Client also processes a Help command, which informs the user of the available commands and an Exit command, which closes both the Client and the Server application sockets and exits both processes.

Commands

Commands	Description
[ text ]	Send regular messages to the Server application.
ping	Asks for the Server application IP address.
handshake	Use messages to simulate / demonstrate the TCP Three-Way Handshake process.
stack	Simulate / demonstrate the TCP/IP Stack encapsulation and sending process.
help	See available commands.
exit	Closes the Client application socket and exits the program.

Object Methods

Being an object oriented program, it tries to hide all the complexity it can inside it's Class.

Method	Description
setup()	Sets up a connection to the Server application through its configured IP and Port.
awaitCommand()	Instructs to await an user Input.
closeSocket()	Closes the application's socket connection.
ping()	Instructs to send the Server application a Ping request and possibly receive an answer from the Server.
handshake()	Sends a 'SYN' message to the server application and awaits for a 'SYN' and an 'ACK' message. Then, it sends the server an 'ACK'.
stack()	Coordenates and displays the process of Stacking lists and pre-determined messages and sends the result to the Server.
encapsulate()	Uses the Stack data structure to insert pre-determined messages and data inside a list, as a means to encapsulate them.
sendMsg()	Sends the Server application a previously collected message.

Server

Click to read

Name

Server - An object oriented Server application that receives messages from the Client application.

Description

Server is an object oriented Server application written in Python that receives messages or commands from the Client application.

When Server receives a message, it displays said message for visual confirmation. When the Server application receives the Ping command, it sends the Client application the IP address it was configured with. When it receives a 'SYN' message, it tries to simulate a TCP Three-Way Handshake, by returning a 'SYN' and an 'ACK' message to the Client application. When it receives a list, it simulates the TCP/IP Stack decapsulation process, as if it were receiving a Frame.

When it loses connection to the Client application, the Server application exits aswell.

Object Methods

Being an object oriented program, it tries to hide all the complexity it can inside it's Class.

Method	Description
setup()	Sets up a TCP/IP server, binds an address and port to the server socket and listens for incoming connections on said port.
awaitConnection()	Instructs to accept incoming connections.
awaitMessage()	Receives incoming messages through a previously established connection.
closeSocket()	Closes the application's socket connection.
ping()	Sends the Client application the configured IP address.
handshake()	Sends the Client application a 'SYN' and an 'ACK' message.
stack()	Coordenates and displays the process of removing elements from a list.
decapsulate()	Removes the last added item on a list and returns said list.
printMsg()	Displays the received message as output.