System.Net.Sockets.TcpListener

TcpListener Class

Listens for incoming TCP connection requests.

Remarks

The TcpListener class provides a simple way to listen for incoming TCP connection requests. It can bind to a specific IP address and port, or to all network interfaces on a machine. Once started, it listens for incoming connection requests and can accept them using the AcceptTcpClient or AcceptSocket methods.

This class is useful for creating server applications that need to accept network connections, such as web servers, chat applications, or custom network services.

Syntax

public class TcpListener : IDisposable
            

Inheritance

• System.Object
• System.Net.Sockets.TcpListener

Implemented Interfaces

• System.IDisposable

Example

The following example demonstrates how to create a simple TCP server that listens on port 8080.

using System;
using System.Net;
using System.Net.Sockets;
using System.Text;

public class SimpleTcpServer
{
    public static void StartListening()
    {
        // Set the TcpListener on port 8080.
        int port = 8080;
        IPAddress localAddr = IPAddress.Parse("127.0.0.1");
        TcpListener server = new TcpListener(localAddr, port);

        // Start listening for connections.
        server.Start();

        Console.WriteLine($"Server started. Listening on port {port}...");

        // Program is always listening.
        while (true)
        {
            Console.WriteLine("Waiting for a connection...");

            // Program blocks while waiting for an incoming connection.
            TcpClient client = server.AcceptTcpClient();
            Console.WriteLine("Connected!");

            NetworkStream stream = client.GetStream();

            // Read and echo data.
            byte[] bytes = new byte[1024];
            int i;

            // Loop to receive all the data sent by the client.
            while ((i = stream.Read(bytes, 0, bytes.Length)) != 0)
            {
                // Translate bytes of the network message into a string.
                string data = Encoding.ASCII.GetString(bytes, 0, i);
                Console.WriteLine($"Received: {data}");

                // Process the data sent by the client.
                data = data.ToUpper();

                byte[] msg = Encoding.ASCII.GetBytes(data);

                // Send back a response.
                stream.Write(msg, 0, msg.Length);
                Console.WriteLine($"Sent: {data}");
            }

            // Shutdown and end the connection.
            client.Close();
        }
    }

    public static void Main(string[] args)
    {
        StartListening();
    }
}