C#

public string Challenge(string servIP, int servPORT)
            {
                byte[] buffer = new byte[100 * 1024];
                byte[] PlayerQuery = { 0xff, 0xff, 0xff, 0xff, 0x55, 0x65 };

                Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);

                IPEndPoint ipEP = new IPEndPoint(IPAddress.Parse(servIP), servPORT);

                EndPoint EP = (EndPoint)ipEP;

                socket.ReceiveTimeout = 1000;

                socket.SendTo(PlayerQuery, PlayerQuery.Length, SocketFlags.None, EP);

                int recvBytes = socket.ReceiveFrom(buffer, ref EP);
                return ParseChallenge(buffer);
            }

            private string ParseChallenge(byte[] resp)
            {
                _CHALLANGE = System.Text.Encoding.ASCII.GetString(resp, 5, 4);
                return _CHALLANGE;
            }

            private SourceQuery ParsePlayers(byte[] resp)
            {
                SourceQuery ret = new SourceQuery();
                int i = 0;
                ret.PPlayers = Encoding.ASCII.GetString(resp);
                /*while (pNr < numPlayers - 2 && offset < resp.Length)
                {
                    offset += 1;
                    string plname = GetString(resp, offset, resp.Length);
                    offset += ret._players[pNr].Name.Length;
                    int plscore = BitConverter.ToInt32(resp, offset);
                    offset += 4;
                    pNr = ret._players.Add(new Player(plname, plscore));
                }*/
                return ret;
            }

            public SourceQuery Players(string servIP, int servPORT)
            {
                byte[] buffer = new byte[4096];
                string challenge = Challenge(servIP, servPORT);
                byte[] PlayerQuery = { 0xff, 0xff, 0xff, 0xff, 0x55 };
                string pQuery = Encoding.ASCII.GetString(PlayerQuery);
                byte[] Query = Encoding.ASCII.GetBytes(pQuery + challenge);

                Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);

                IPEndPoint ipEP = new IPEndPoint(IPAddress.Parse(servIP), servPORT);

                EndPoint EP = (EndPoint)ipEP;

                socket.ReceiveTimeout = 1500;

                socket.SendTo(PlayerQuery, PlayerQuery.Length, SocketFlags.None, EP);

                int recvBytes = socket.ReceiveFrom(buffer, ref EP);
                return ParsePlayers(buffer);
            }