int port = int.Parse(textBox2.Text);   
            textBox1.AppendText("连接等待.........");
            UdpClient receivingUdpClient = new UdpClient(port);//创建UDPClient对象
            IPEndPoint RemoteIpEndPoint = new IPEndPoint(IPAddress.Any, port);//创建IPEndPoint对象
            while(true)
            {
                    Byte[] receiveBytes = receivingUdpClient.Receive(ref RemoteIpEndPoint);//接收远程发送的UDP数据报,就是卡在这儿了
                    if (receiveBytes.Length > 0)
                    {
                        string returnData = Encoding.ASCII.GetString(receiveBytes);//将字节数组转换为字符串
                        textBox1.AppendText("This is the message you received " +//输出字符串信息
                                                    returnData.ToString());
                        textBox1.AppendText("This message was sent from " +//输出远程主机地址及发送数据报使用的端口
                                                    RemoteIpEndPoint.Address.ToString() +
                                                    " on their port number " +
                                                    RemoteIpEndPoint.Port.ToString());
                        DateTime currentTime = DateTime.Now;
                        string strtime = currentTime.Hour.ToString() + ":" + currentTime.Minute.ToString() + ":"
                                          + currentTime.Second.ToString() + ":"
                                          + currentTime.Millisecond.ToString();
                        byte[] mybyte = Encoding.Default.GetBytes(strtime);
                        receivingUdpClient.Send(mybyte, strtime.Length, RemoteIpEndPoint);
                    }
              }
        
        }