[Jakarin Chawachat]

using System;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Text;
class MyTcpListener
{
  public static void Main()
  {
      TcpListener server = null;
      try
      {
          // Set the TcpListener on port 13000.
          Int32 port = 13000;
          IPAddress localAddr = IPAddress.Parse("127.0.0.1");
          // TcpListener server = new TcpListener(port);
          server = new TcpListener(localAddr, port);
          // Start listening for client requests.
          server.Start();
          // Buffer for reading data
          Byte[] bytes = new Byte[256];
          String data = null;
          // Enter the listening loop. 
          while (true)
          {
              Console.Write("Waiting for a connection... ");
              // Perform a blocking call to accept requests. 
              // You could also user server.AcceptSocket() here.
              TcpClient client = server.AcceptTcpClient();
              Console.WriteLine("Connected!");
              data = null;
              // Get a stream object for reading and writing
              NetworkStream stream = client.GetStream();
              int i;
              // Loop to receive all the data sent by the client. 
              while ((i = stream.Read(bytes, 0, bytes.Length)) != 0)
              {
                  // Translate data bytes to a ASCII string.
                  data = System.Text.Encoding.ASCII.GetString(bytes, 0, i);
                  Console.WriteLine("Received: {0}", data);
                  // Process the data sent by the client.
                  data = data.ToUpper();
                  byte[] msg = System.Text.Encoding.ASCII.GetBytes(data);
                  // Send back a response.
                  stream.Write(msg, 0, msg.Length);
                  Console.WriteLine("Sent: {0}", data);
              }
              // Shutdown and end connection
              client.Close();
          }
      }
      catch (SocketException e)
      {
          Console.WriteLine("SocketException: {0}", e);
      }
      finally
      {
          // Stop listening for new clients.
          server.Stop();
      }
      Console.WriteLine("\nHit enter to continue...");
      Console.Read();
  }
}