Client-Server Message Transmission Application over TCP/IP

A minimal implementation of a TCP/IP protocol using socket programming in C to create a message transmission application.

It's surreal that, if two machines are connected over same LAN (mobile hotspot/wifi), a communication can be established between the two machines using sockets without the need of connecting the machines physically with any wire.

Features

• Uses IPv4 and TCP sockets
• Server listens for connections on port 2000
• Client connects to the server and sends messages
• Supports bidirectional message transmission

Prerequisites

Ensure you have the following installed on your system:

• GCC compiler
• A Linux or macOS system (Windows users can use WSL or MinGW)

Setup Instructions

1. Clone the Repository

$ git clone <repository_url>
$ cd <repository_name>

2. Compile the Server and Client

You can compile manually using gcc:

$ gcc -o server server.c
$ gcc -o client client.c

3. Run the Server

Start the server first to listen for incoming connections:

$ ./server

The server will bind to port 2000 and wait for connections.

4. Run the Client on the Same Machine

Open another terminal and run the client to connect to the server:

$ ./client

You should see a message indicating a successful connection.

5. Run the Client on a Different Machine

If you want to run the client on a different machine:

1. Find the server machine's IP address:

   $ ifconfig a | grep inet

   Look for the appropriate network interface (e.g., 192.168.x.x on a Wi-Fi network).
2. Modify the client.c file to replace 127.0.0.1 with the server's IP address:

   char* ip = "192.168.x.x"; // Replace with the server's IP

3. Recompile the client:

   $ gcc -o client client.c

4. Run the client on the second machine:

   $ ./client

5. Ensure both machines are connected to the same network.

6. Send Messages

Once the client is connected, you can start sending messages from the client terminal. The server will receive and print them. To exit, type exit and press Enter in the client terminal.

7. Close the Server

Once communication is done, stop the server with Ctrl + C.

Troubleshooting

• Ensure both server and client are running on the same network.
• If the server is running on another machine, update the client's IP address accordingly in client.c.
• Check if server is bound on port 2000:

  $ lsof -i :2000

• If you get permission issues, try running the server with:

  $ sudo ./server