// Displays sending with a connected socket
// using the overload that takes a buffer.
public static int SendReceiveTest1(Socket server)
{
  byte[] msg = Encoding.UTF8.GetBytes("This is a test");
  byte[] bytes = new byte[256];
  try
  {
    // Blocks until send returns.
    int i = server.Send(msg);
    Console.WriteLine("Sent {0} bytes.", i);
    // Get reply from the server.
    i = server.Receive(bytes);
    Console.WriteLine(Encoding.UTF8.GetString(bytes));
  }
  catch (SocketException e)
  {
    Console.WriteLine("{0} Error code: {1}.", e.Message, e.ErrorCode);
    return (e.ErrorCode);
  }
  return 0;
}

// Establish the local endpoint for the socket.
IPHostEntry ipHost = Dns.GetHostEntry(Dns.GetHostName());
IPAddress ipAddr = ipHost.AddressList[0];
IPEndPoint ipEndPoint = new IPEndPoint(ipAddr, 11000);
// Create a TCP socket.
Socket client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
// Connect the socket to the remote endpoint.
client.Connect(ipEndPoint);
// There is a text file test.txt located in the root directory.
string fileName = "C:\\test.txt";
// Send file fileName to remote device
Console.WriteLine("Sending {0} to the host.", fileName);
client.SendFile(fileName);
// Release the socket.
client.Shutdown(SocketShutdown.Both);
client.Close();