private static TcpListener tcl;
        //Generate policy
        private static string response = "" +
                                    "\0";
        public static void Main(string[] args)
        {
            Console.WriteLine("Starting up server...");
 
            tcl = new TcpListener(IPAddress.Any, 843);
            tcl.Start();
            tcl.BeginAcceptSocket(new AsyncCallback(AcceptCallback), tcl);
            Console.WriteLine("Hit enter/return to close");
            Console.ReadLine();
        }
        private static void AcceptCallback(IAsyncResult ar)
        {
            try
            {
                TcpListener listener = null;
                Socket client = null;
 
                listener = (TcpListener)ar.AsyncState;
                client = listener.EndAcceptSocket(ar);
                NetworkStream ns = new NetworkStream(client);
                StreamReader sr = new StreamReader(ns);
                StreamWriter sw = new StreamWriter(ns);
 
                sr.Read();
                //Send policy
                sw.Write(response);
                sw.Flush();
                ns.Flush();
                //Cleanup
                sw.Close();
                sr.Close();
                ns.Close();
                client.Close();
                //Do it again!
                tcl.BeginAcceptSocket(new AsyncCallback(AcceptCallback), tcl);
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
                return;
            }
        }