public static bool PortIsUse(int port)
  {
   bool isUse = false;
   IPGlobalProperties ipProperties = IPGlobalProperties.GetIPGlobalProperties();
   IPEndPoint[] ipEndPoints = ipProperties.GetActiveTcpListeners();//找到已用端口
   foreach (IPEndPoint endPoint in ipEndPoints)
   {
    if (endPoint.Port == port)//判断是否存在
    {
     isUse= true;
     break;
    }
   }
   return isUse;
  }

TcpListener tcpl = new TcpListener(new IPAddress(new byte[] { 127, 0, 0, 1 }), 1111);//定义一个TcpListener对象监听本地的1111端口
   tcpl.Start();//监听开始
   while (true)
   {
    Socket s = tcpl.AcceptSocket();//挂起一个Socket对象
    string remote = s.RemoteEndPoint.ToString();//获取发送端的IP及端口转为String备用
    Byte[] stream = new Byte[1024];
    s.Receive(stream);//接收发送端发过来的数据,写入字节数组
    //BGW_Handle.ReportProgress(1, "接收来自[" + remote + "]信息");
    string _data = Encoding.UTF8.GetString(stream);//将字节数据数组转为String
    s.Send(stream);//将接收到的内容，直接返回接收端
    s.Shutdown(SocketShutdown.Both);
   }
   tcpl.Stop();//停止监听

IPAddress ip = IPAddress.Parse("127.0.0.1");//接收端所在IP
   IPEndPoint ipEnd = new IPEndPoint(ip, 1111);//接收端所监听的接口
   Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);//初始化一个Socket对象
   try
   {
    socket.Connect(ipEnd);//连接指定IP&端口
   }
   catch (SocketException e)
   {
    Console.WriteLine("连接失败");
    Console.WriteLine(e.ToString());
    return;
   }
   socket.Send(Encoding.UTF8.GetBytes("1234567890"));//发送数据
   while (true)//定义一个循环接收返回数据
   {
    byte[] data = new byte[1024];
    socket.Receive(data);//接收返回数据
    string stringData = Encoding.UTF8.GetString(data);
    if (!string.IsNullOrWhiteSpace(stringData))
    {
     Console.Write(stringData);
     break;
    }
   }29    socket.Shutdown(SocketShutdown.Both);
   socket.Close();//关闭Socket