IPEndPoint remoteHost = null;

            while (udpClient != null && Thread.CurrentThread.ThreadState.Equals(System.Threading.ThreadState.Running ))

            {

                try

                {

                    byte[] buf = udpClient.Receive(ref remoteHost);

                    string bufs = Encoding.UTF8.GetString(buf);

                    if ((bufs.StartsWith("##IP")) && (bufs.EndsWith("#CMD_END##")))

                    {

                        int ip_addr_start_pos = bufs.IndexOf("##IP:") + 5;

                        string ip_address = bufs.Substring(ip_addr_start_pos, bufs.IndexOf("#IPEND#") - ip_addr_start_pos);

                        int port_start_pos = bufs.IndexOf("##PORT:") + 7;

                        int port = Convert.ToInt32(bufs.Substring(port_start_pos, bufs.IndexOf("#PORTEND#") - port_start_pos));

                        //获取传来的ORDER指令，完成对客户端的控制

                        int order_start_pos = bufs.IndexOf("ORDER:") + 6;

                        string recvStr = bufs.Substring(order_start_pos, bufs.IndexOf("#CMD_END##") - order_start_pos);

                        //依据不同的信息来处理客户机

                        if (recvStr != "")

                        {

                            switch (recvStr)

                            {

                                case "LOGOUT"://注销本机

                                    DoExitWin(EWX_LOGOFF);

                                    //也可以用下面的方式

                                    //ExitWindowsEx(0, 0);

                                    break;

                                case "LOCK"://自定义的锁屏方法锁定屏幕//锁定鼠标及键盘//屏蔽ctrl+alt+delete

                                    BlockInput(true);

                                    FileStream fs = new FileStream(Environment.ExpandEnvironmentVariables("%windir%\\system32\\taskmgr.exe"), FileMode.Open);