System.Net.Sockets

Provides classes that enable a coarse-grained control over network access, including classes that support socket operations.

Namespace: System.Net

Assembly: System.Net.Sockets.dll

Classes

AddressFamily Enumeration that specifies the base address structures used by the Socket class.
IPAddress Represents a Transmission Control Protocol/Internet Protocol (IP) address.
IPEndPoint Represents a network endpoint as an IP address and a port number.
NetworkStream Provides the underlying stream of bytes for network access.
ProtocolFamily Enumeration that specifies the protocols used by the Socket class.
ProtocolType Enumeration that specifies Internet protocol types.
Socket Provides a highly flexible and extensible set of classes for network programming.
SocketAddress Represents a socket address.
SocketError Enumeration that describes socket errors.
SocketFlags Enumeration that specifies socket options.
SocketOptionLevel Enumeration that specifies socket option levels.
SocketOptionName Enumeration that specifies socket option names.
SocketType Enumeration that specifies the types of sockets available.
TcpClient Provides a stream-based TCP connection.
UdpClient Provides UDP network services.

Structures

EndPoint Abstract base class for network endpoints.
SocketAsyncEventArgs Represents the state of an asynchronous socket operation.

Interfaces

ISocketAsyncEventArgsFactory Defines a factory for creating SocketAsyncEventArgs objects.

Examples

Creating a simple TCP Listener


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

public class SimpleTcpListener
{
    public static void StartListening()
    {
        // Set the IP address and port number to listen on.
        IPAddress ipAddress = IPAddress.Parse("127.0.0.1");
        int port = 11000;
        IPEndPoint localEndPoint = new IPEndPoint(ipAddress, port);

        // Create a TCP/IP socket.
        Socket listener = new Socket(ipAddress.AddressFamily,
            SocketType.Stream, ProtocolType.Tcp);

        try
        {
            listener.Bind(localEndPoint);
            listener.Listen(10); // Start listening for connections.

            Console.WriteLine("Waiting for a connection...");
            Socket handler = listener.Accept(); // Program is suspended while waiting for connection.

            // Incoming data from the client.
            string data = null;
            byte[] bytes = new byte[1024];
            int bytesRec = handler.Receive(bytes);
            data = Encoding.ASCII.GetString(bytes, 0, bytesRec);

            Console.WriteLine($"Text received : {data}");

            // Echo the data back to the client.
            byte[] msg = Encoding.ASCII.GetBytes($"Echo: {data}");
            handler.Send(msg);

            handler.Shutdown(SocketShutdown.Both);
            handler.Close();
        }
        catch (Exception e)
        {
            Console.WriteLine(e.ToString());
        }
        finally
        {
            if (listener != null)
            {
                listener.Close();
            }
        }
    }

    // You would call StartListening() from your Main method or another entry point.
    // public static void Main(string[] args) { StartListening(); }
}