using System;
using System.Collections.Generic;
using System.Text;
using System.Net.Sockets;
using System.Net;
using System.IO;
namespace ConsoleApplication1
{
  Class Program
  {
    static void Main (String[] args)
    {
      // 1. to create a socket
      Socket sListen = new Socket (AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
      // 2. Fill IP
      IPAddress IP = IPAddress.Parse ("127.0.0.1");
      IPEndPoint IPE = new IPEndPoint (IP, 4321);
      // 3. binding
      sListen.Bind (IPE);
      // 4. Monitor
      Console.WriteLine ("Service is listening ...");
      sListen.Listen (2);
      // 5. loop to accept client connection requests
      while (true)
      {
        Socket clientSocket;
        try
        {
          clientSocket = sListen.Accept ();
        }
        catch
        {
          throw;
        }
        // send data to the client
        //clientSocket.Send (Encoding.Unicode.GetBytes ("I am a server, you there?? !!!!"));
        // send the file
        byte[] buffer = ReadImageFile ("1.jpg");
        clientSocket.Send (buffer, buffer.Length, SocketFlags.None);
        Console.WriteLine ("Send success!");
      }
    }
    private static byte[] ReadImageFile (String img)
    {
      FileInfo fileinfo = new FileInfo (img);
      byte[] buf = new byte[fileInfo.Length];
      FileStream fs = new FileStream (img, FileMode.Open, FileAccess.Read);
      fs.Read (buf, 0, buf.Length);
      fs.Close ();
      //fileInfo.Delete ();
      GC.ReRegisterForFinalize (fileinfo);
      GC.ReRegisterForFinalize (fs);
      return buf;
    }
  }
}

using System;
using System.Collections.Generic;
using System.Text;
using System.Net.Sockets;
using System.Net;
using System.IO;
namespace ConsoleApplication2
{
  Class Program
  {
    static void Main (String[] args)
    {
      // 1. to create a socket
      Socket S = new Socket (AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
      // 2. fill in the remote IP
      IPAddress IP = IPAddress.Parse ("127.0.0.1");
      IPEndPoint IPE = new IPEndPoint (IP, 4321);
      Console.WriteLine ("started connection service ....");
      // 3. connect to the server
      s.Connect (IPE);
      // 4. receive data
      byte[] buffer = new byte[1000000];
      s.Receive (buffer, buffer.Length, SocketFlags.None);
      //var Msg = Encoding.Unicode.GetString (buffer);
      //Console.WriteLine ("received message: (0)", msg);
      Console.WriteLine ("Receive success");
      FileStream fs = File.Create ("1.jpg");
      fs.Write (buffer, 0, buffer.Length);
      fs.Close ();
      Console.ReadKey ();
    }
  }
}