Connect() public method

Establishes a connection to a remote device and optionally negotiates a secure transport protocol.
The remoteEP parameter is a null reference (Nothing in Visual Basic). An operating system error occurs while accessing the . The SecureSocket has been closed. The security negotiation failed.
public Connect ( EndPoint remoteEP ) : void
remoteEP System.Net.EndPoint An that represents the remote device.
return void
Exemplo n.º 1
0
 private void DownloadFile(Url url, int choice)
 {
     SecurityOptions options = new SecurityOptions(SecureProtocol.None);;
     m_Socket = new SecureSocket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp, options);
     // connect to the FTP server using a normal TCP connection
     m_Socket.Connect(new IPEndPoint(Dns.GetHostEntry(url.Host).AddressList[0], url.Port));
     // wait for the server hello
     ReceiveReply();
     // if the user selected to use the AUTH command..
     if (choice == 2) {
         // ..send the command to the server and start the SSL handshake
         DoAuthCommand(url.Host);
     }
     // log on and quit
     if (!SendCommand("USER " + url.Username))
         return;
     if (!SendCommand("PASS " + url.Password))
         return;
     if (!SendCommand("QUIT"))
         return;
     // clean up
     m_Socket.Shutdown(SocketShutdown.Both);
     m_Socket.Close();
 }
        public bool Connect(Uri connectUri)
        {
            _path = connectUri.PathAndQuery;
            _version = Protocols.Http2;
            _scheme = connectUri.Scheme;
            _host = connectUri.Host;
            _port = connectUri.Port;
            ServerUri = connectUri.Authority;

            if (_sessionAdapter != null)
            {
                return false;
            }

            try
            {
                int port = connectUri.Port;

                int securePort;

                if (!int.TryParse(ConfigurationManager.AppSettings["securePort"], out securePort))
                {
                    Http2Logger.LogError("Incorrect port in the config file!");
                    return false;
                }


                //Connect alpn extension, set known protocols
                var extensions = new[] {ExtensionType.Renegotiation, ExtensionType.ALPN};

                Options = port == securePort
                               ? new SecurityOptions(SecureProtocol.Tls1, extensions, new[] { Protocols.Http1, Protocols.Http2 },
                                                     ConnectionEnd.Client)
                               : new SecurityOptions(SecureProtocol.None, extensions, new[] { Protocols.Http1, Protocols.Http2 },
                                                     ConnectionEnd.Client);

                Options.VerificationType = CredentialVerification.None;
                Options.Certificate = Org.Mentalis.Security.Certificates.Certificate.CreateFromCerFile(CertificatePath);
                Options.Flags = SecurityFlags.Default;
                Options.AllowedAlgorithms = SslAlgorithms.RSA_AES_256_SHA | SslAlgorithms.NULL_COMPRESSION;

                var socket = new SecureSocket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp, Options);
                using (var monitor = new ALPNExtensionMonitor())
                {
                    monitor.OnProtocolSelected += (o, args) => { _selectedProtocol = args.SelectedProtocol; };
                    socket.Connect(new DnsEndPoint(connectUri.Host, connectUri.Port), monitor);

                    _clientStream = new DuplexStream(socket, true);

                    if (_useHandshake)
                    {
                        MakeHandshakeEnvironment();
                        //Handshake manager determines what handshake must be used: upgrade or secure

                        if (socket.SecureProtocol != SecureProtocol.None)
                        {
                            socket.MakeSecureHandshake(Options);
                            _selectedProtocol = socket.SelectedProtocol;
                        }

                        if (socket.SecureProtocol == SecureProtocol.None || _selectedProtocol == Protocols.Http1)
                        {
                            try
                            {
                                var handshakeResult = new UpgradeHandshaker(_environment).Handshake();
                                _environment.Add(HandshakeKeys.Result, handshakeResult);
                                _useHttp20 = handshakeResult[HandshakeKeys.Successful] as string == HandshakeKeys.True;

                                if (!_useHttp20)
                                {
                                    Dispose(false);
                                    return true;
                                }
                            }
                            catch (Http2HandshakeFailed ex)
                            {
                                if (ex.Reason == HandshakeFailureReason.InternalError)
                                {
                                    _useHttp20 = false;
                                }
                                else
                                {
                                    Http2Logger.LogError("Specified server did not respond");
                                    Dispose(true);
                                    return false;
                                }
                            }
                        }
                    }
                }

                Http2Logger.LogDebug("Handshake finished");

                if (_useHttp20)
                {
                    //TODO provide transport info
                    _sessionAdapter = new Http2ClientMessageHandler(_clientStream, ConnectionEnd.Client, default(TransportInformation),
                                                                     CancellationToken.None);
                }
            }
            catch (SocketException)
            {
                Http2Logger.LogError("Check if any server listens port " + connectUri.Port);
                Dispose(true);
                return false;
            }
            catch (Exception ex)
            {
                Http2Logger.LogError("Unknown connection exception was caught: " + ex.Message);
                Dispose(true);
                return false;
            }

            return true;
        }
Exemplo n.º 3
0
		//sendraw SSL
		public string sendraw (string ipRaw, string portRaw, string payloadRaw, int size, int TimeOut, int retry, bool useSSL) {
			
			IPHostEntry IPHost = Dns.Resolve(ipRaw); 
			string []aliases = IPHost.Aliases; 
			IPAddress[] addr = IPHost.AddressList; 
			IPEndPoint iep ;
			SecureProtocol sp;
			sp=SecureProtocol.Ssl3;
			SecureSocket s=null; 
			SecurityOptions options = new SecurityOptions(sp);
			options.Certificate = null;
			options.Protocol=SecureProtocol.Ssl3;
			options.Entity = ConnectionEnd.Client;
			options.CommonName = ipRaw;
			options.VerificationType = CredentialVerification.None;
			options.Flags = SecurityFlags.IgnoreMaxProtocol;
			options.AllowedAlgorithms = SslAlgorithms.ALL;

			while (retry>0){
				try {
				
					s = new SecureSocket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp, options);
					s.SetSocketOption (SocketOptionLevel.Socket, SocketOptionName.SendTimeout, 4000);
					s.SetSocketOption (SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, 4000);
			
					iep	= new IPEndPoint(addr[0],Convert.ToInt32(portRaw));
					s.Connect(iep);

					ASCIIEncoding asen= new ASCIIEncoding();
					byte[] ba=asen.GetBytes(payloadRaw);
					s.Send(ba,ba.Length,System.Net.Sockets.SocketFlags.None);
					

					byte[] bb=new byte[size];
					
					int k=1;
					string response="";
					while (k>0){
						k=s.Receive(bb,size,System.Net.Sockets.SocketFlags.None);					
						response+=Encoding.Default.GetString(bb,0,k);
					}
					s.Close();
					GC.Collect();
					GC.WaitForPendingFinalizers();

					return response;

				}
				catch(Exception ex) {
					retry--;
					Thread.Sleep(1000);
				}
			}
			
			return "Timeout or retry count exceeded";
		}
Exemplo n.º 4
0
        public bool Connect(Uri connectUri)
        {
            _path = connectUri.PathAndQuery;
            _version = Protocols.Http2;
            _scheme = connectUri.Scheme;
            _host = connectUri.Host;
            _port = connectUri.Port;
            ServerUri = connectUri.Authority;

            if (_clientSession != null)
            {
                return false;
            }

            try
            {
                int port = connectUri.Port;

                int securePort;

                if (!int.TryParse(ConfigurationManager.AppSettings["securePort"], out securePort))
                {
                    Http2Logger.LogError("Incorrect port in the config file!");
                    return false;
                }


                //Connect alpn extension, set known protocols
                var extensions = new[] {ExtensionType.Renegotiation, ExtensionType.ALPN};

                Options = port == securePort
                               ? new SecurityOptions(SecureProtocol.Tls1, extensions, new[] { Protocols.Http1, Protocols.Http2 },
                                                     ConnectionEnd.Client)
                               : new SecurityOptions(SecureProtocol.None, extensions, new[] { Protocols.Http1, Protocols.Http2 },
                                                     ConnectionEnd.Client);

                Options.VerificationType = CredentialVerification.None;
                Options.Certificate = Org.Mentalis.Security.Certificates.Certificate.CreateFromCerFile(CertificatePath);
                Options.Flags = SecurityFlags.Default;
                Options.AllowedAlgorithms = SslAlgorithms.RSA_AES_256_SHA | SslAlgorithms.NULL_COMPRESSION;

                _socket = new SecureSocket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp, Options);
                IDictionary<string, object> handshakeResult = null;
                using (var monitor = new ALPNExtensionMonitor())
                {
                    monitor.OnProtocolSelected += (o, args) => { _selectedProtocol = args.SelectedProtocol; };
                    _socket.Connect(new DnsEndPoint(connectUri.Host, connectUri.Port), monitor);
                    
                    if (_useHandshake)
                    {
                        var handshakeEnvironment = MakeHandshakeEnvironment(_socket);
                        //Handshake manager determines what handshake must be used: upgrade or secure
                        handshakeResult = HandshakeManager.GetHandshakeAction(handshakeEnvironment).Invoke();

                        Http2Logger.LogDebug("Handshake finished");

                        if (_selectedProtocol == Protocols.Http1)
                        {
                            _useHttp20 = false;
                            return true;
                        }
                    }
                }

                SendSessionHeader();
                _useHttp20 = true;
                _clientSession = new Http2Session(_socket, ConnectionEnd.Client, _usePriorities, _useFlowControl, handshakeResult);

                //For saving incoming data
                _clientSession.OnFrameReceived += FrameReceivedHandler;
                _clientSession.OnRequestSent += RequestSentHandler;
                _clientSession.OnSessionDisposed += (sender, args) => Dispose(false);
            }
            catch (Http2HandshakeFailed ex)
            {
                if (ex.Reason == HandshakeFailureReason.InternalError)
                {
                    _useHttp20 = false;
                }
                else
                {
                    Http2Logger.LogError("Specified server did not respond");
                    Dispose(true);
                    return false;
                }
            }
            catch (SocketException)
            {
                Http2Logger.LogError("Check if any server listens port " + connectUri.Port);
                Dispose(true);
                return false;
            }
            catch (Exception ex)
            {
                Http2Logger.LogError("Unknown connection exception was caught: " + ex.Message);
                Dispose(true);
                return false;
            }

            return true;
        }
Exemplo n.º 5
0
        public string sendraw(string ipRaw, string portRaw, string payloadRaw, int size, int TimeOut, bool useSSL)
        {
            int retry = (int)updownRetryTCP.Value;
            IPHostEntry IPHost = Dns.GetHostEntry(ipRaw);
            //IPHostEntry IPHost = Dns.Resolve(ipRaw); 
            string[] aliases = IPHost.Aliases;
            IPAddress[] addr = IPHost.AddressList;
            IPEndPoint iep;
            SecureProtocol sp;
            sp = SecureProtocol.Ssl3;
            SecureSocket s = null;
            SecurityOptions options = new SecurityOptions(sp);
            options.Certificate = null;
            options.Protocol = SecureProtocol.Ssl3;
            options.Entity = ConnectionEnd.Client;
            options.CommonName = ipRaw;
            options.VerificationType = CredentialVerification.None;
            options.Flags = SecurityFlags.IgnoreMaxProtocol;
            options.AllowedAlgorithms = SslAlgorithms.ALL;

            while (retry > 0)
            {
                try
                {

                    s = new SecureSocket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp, options);
                    s.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.SendTimeout, 4000);
                    s.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, 4000);

                    iep = new IPEndPoint(addr[0], Convert.ToInt32(portRaw));


                    s.Connect(iep);


                    ASCIIEncoding asen = new ASCIIEncoding();
                    byte[] ba = asen.GetBytes(payloadRaw);
                    s.Send(ba, ba.Length, System.Net.Sockets.SocketFlags.None);

                    byte[] bb = new byte[size];


                    string response = "";
                    int k = 1;
                    while (k > 0)
                    {
                        k = s.Receive(bb, size, System.Net.Sockets.SocketFlags.None);
                        for (int i = 0; i < k; i++)
                        {
                            response += Convert.ToChar(bb[i]);
                        }
                    }
                    s.Close();
                    GC.Collect();
                    GC.WaitForPendingFinalizers();

                    return response;

                }


                catch
                {
                    retry--;
                    lblStatus.Text = "Network problem - retrying\r\n";
                    lblNiktoAI.Text = "Network problem - retrying\r\n";
                    Thread.Sleep(1000);
                }
            }

            return "Retry count (" + updownRetryTCP.Value.ToString() + ") exceeded";
        }
Exemplo n.º 6
0
        public static DuplexStream GetHandshakedDuplexStream(string address, bool allowHttp2Communication = true, bool useMock = false)
        {
            string selectedProtocol = null;

            var extensions = new[] { ExtensionType.Renegotiation, ExtensionType.ALPN };
            var useHandshake = ConfigurationManager.AppSettings["handshakeOptions"] != "no-handshake";

            var protocols = new List<string> { Protocols.Http1 };
            if (allowHttp2Communication)
            {
                protocols.Add(Protocols.Http2);
            }

            var options = UseSecurePort
                              ? new SecurityOptions(SecureProtocol.Tls1, extensions, protocols,
                                                    ConnectionEnd.Client)
                              : new SecurityOptions(SecureProtocol.None, extensions, protocols,
                                                    ConnectionEnd.Client);

            options.VerificationType = CredentialVerification.None;
            options.Certificate = Org.Mentalis.Security.Certificates.Certificate.CreateFromCerFile(@"certificate.pfx");
            options.Flags = SecurityFlags.Default;
            options.AllowedAlgorithms = SslAlgorithms.RSA_AES_256_SHA | SslAlgorithms.NULL_COMPRESSION;

            var sessionSocket = new SecureSocket(AddressFamily.InterNetwork, SocketType.Stream,
                                                ProtocolType.Tcp, options);

            using (var monitor = new ALPNExtensionMonitor())
            {
                monitor.OnProtocolSelected += (sender, args) => { selectedProtocol = args.SelectedProtocol; };

                var uri = new Uri(GetAddress() + address);

                sessionSocket.Connect(new DnsEndPoint(uri.Host, uri.Port), monitor);

                if (useHandshake)
                {
                    sessionSocket.MakeSecureHandshake(options);
                }
            }

            //SendSessionHeader(sessionSocket);

            return useMock ? new Mock<DuplexStream>(sessionSocket, true).Object : new DuplexStream(sessionSocket, true);
        }
        private SecureSocket CreateSocketByUri(Uri uri)
        {
            if (!String.Equals(uri.Scheme, "http", StringComparison.OrdinalIgnoreCase) &&
                !String.Equals(uri.Scheme, "https", StringComparison.OrdinalIgnoreCase))
                throw new InvalidOperationException("Unrecognized scheme: " + uri.Scheme);

            SecurityOptions options;
            var extensions = new ExtensionType[] { ExtensionType.Renegotiation, ExtensionType.ALPN };
            if (!String.Equals(uri.Scheme, "https", StringComparison.OrdinalIgnoreCase))
            {
                options = new SecurityOptions(SecureProtocol.None, null, ConnectionEnd.Client);
            }
            else
            {
                options = new SecurityOptions(SecureProtocol.Tls1, extensions, ConnectionEnd.Client);
            }

            options.Entity = ConnectionEnd.Client;
            options.CommonName = uri.Host;
            options.VerificationType = CredentialVerification.None;
            options.Certificate = Org.Mentalis.Security.Certificates.Certificate.CreateFromCerFile(@"certificate.pfx");
            options.Flags = SecurityFlags.Default;
            options.AllowedAlgorithms = SslAlgorithms.RSA_AES_128_SHA | SslAlgorithms.NULL_COMPRESSION;

            var s = new SecureSocket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp, options);
            s.OnClose += SocketOnClose;

            try
            {
                if (String.Equals(uri.Scheme, "https", StringComparison.OrdinalIgnoreCase))
                {
                    s.OnHandshakeFinish += this.HandshakeFinishedHandler;
                }

                s.Connect(new Net.DnsEndPoint(uri.Host, uri.Port));

                if (String.Equals(uri.Scheme, "https", StringComparison.OrdinalIgnoreCase))
                {

                    this.handshakeFinishedEventRaised.WaitOne(60000);

                    if (!s.IsNegotiationCompleted)
                    {
                        throw new Exception("Handshake failed");
                    }

                    if (!s.Connected)
                    {
                        throw new Exception("Connection was lost!");
                    }

                    s.OnHandshakeFinish -= this.HandshakeFinishedHandler;

                    this.ApplyProtocolSelectionResults(options.GetSelectedProtocol());
                }
            }
            catch (Exception ex)
            {
                s.Close();
                // Emitting protocol error. It will emit session OnError
                if (OnError != null)
                    this.OnError(this, new ProtocolErrorEventArgs(ex));

                throw;
            }

            return s;
        }
Exemplo n.º 8
0
 public void Start()
 {
     try {
         // ask the user for SMTP server, port and the type of connection
         Console.Write("Host to connect to: ");
         string server = Console.ReadLine().Trim();
         Console.Write("Port: ");
         string port = Console.ReadLine().Trim();
         Console.Write("Connection type [0 = normal connection, 1 = direct TLS connection, 2 = indirect TLS connection (using STARTTLS command)]: ");
         string type = Console.ReadLine().Trim();
         if (Array.IndexOf(new string[]{"0", "1", "2"}, type) == -1) {
             Console.WriteLine("Invalid connection type.");
             return;
         }
         Console.WriteLine("Please enter the email address you wish to send an email to:");
         string address = Console.ReadLine().Trim();
         // create a new SecurityOptions instance
         SecurityOptions options = new SecurityOptions(SecureProtocol.None);
         // allow only secure ciphers to be used. Currently, the seure ciphers are:
         // the AES algorithm [128 or 256 bit keys], the RC4 algorithm [128 bit keys]
         // or TipleDES [168 bit keys]
         options.AllowedAlgorithms = SslAlgorithms.SECURE_CIPHERS;
         // the SecureSocket should be a client socket
         options.Entity = ConnectionEnd.Client;
         // we will use manual verification of the server certificate
         options.VerificationType = CredentialVerification.Manual;
         // when the server certificate is receives, the SecureSocket should call
         // the OnVerify method
         options.Verifier = new CertVerifyEventHandler(OnVerify);
         // use the default flags
         options.Flags = SecurityFlags.Default;
         // the common name is the domain name or IP address of the server
         options.CommonName = server;
         // if the user chose a direct TLS connection, set the protocol to TLS1
         if (type == "1") {
             options.Protocol = SecureProtocol.Tls1;
         }
         // create the new secure socket
         Connection = new SecureSocket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp, options);
         // connect to the SMTP server
         Connection.Connect(new IPEndPoint(Dns.GetHostEntry(server).AddressList[0], int.Parse(port)));
         // wait for the server hello message
         if (!IsReplyOK(Receive())) {
             Console.WriteLine("Server disallowed connection.");
             return;
         }
         // if the user selected an indirect TLS connection, issue
         // a EHLO command. Otherwise, stick to the standard HELO command.
         if (type == "2") // STARTTLS connection
             Send("EHLO SmtpClient.Mentalis.org\r\n");
         else
             Send("HELO SmtpClient.Mentalis.org\r\n");
         if (!IsReplyOK(Receive())) {
             Console.WriteLine("HELLO failed.");
             return;
         }
         // if the user selected an indirect TLS connection, issue
         // the STARTTLS command
         if (type == "2") {
             // send the STARTTLS command to the server
             Send("STARTTLS\r\n");
             // make sure the server supports the STARTTLS command
             if (!IsReplyOK(Receive())) {
                 Console.WriteLine("STARTTLS failed.");
                 return;
             }
             // change the protocol from SecureProtocol.None
             // to SecureProtocol.Tls1
             options.Protocol = SecureProtocol.Tls1;
             // start the TLS handshake
             Connection.ChangeSecurityProtocol(options);
             // after this line, we're using an encrypted TLS connection
         }
         // from here on, act as if the SecureSocket is a normal Socket
         Send("MAIL FROM: [email protected]\r\n"); // [email protected] is not a real email address
         if (!IsReplyOK(Receive())) {
             Console.WriteLine("MAIL FROM failed.");
             return;
         }
         Send("RCPT TO:" + address + "\r\n");
         if (!IsReplyOK(Receive())) {
             Console.WriteLine("RCPT TO failed.");
             return;
         }
         Send("DATA\r\n");
         if (!IsReplyOK(Receive())) {
             Console.WriteLine("DATA failed.");
             return;
         }
         Send(TestMail.Replace("#ADDRESS#", address) + "\r\n.\r\n");
         if (!IsReplyOK(Receive())) {
             Console.WriteLine("Sending of e-mail failed.");
             return;
         }
         Send("QUIT\r\n");
         if (!IsReplyOK(Receive())) {
             Console.WriteLine("QUIT failed.");
         }
         Connection.Shutdown(SocketShutdown.Both);
     } catch (Exception e) {
         Console.WriteLine("An error occurred [" + e.Message + "]");
         Console.WriteLine(e);
     } finally {
         if (Connection != null) {
             Connection.Close();
         }
     }
 }
Exemplo n.º 9
0
 /// <summary>
 /// Download a file using the synchronous Socket methods.
 /// </summary>
 /// <param name="url">The URL to download.
 /// </param>
 /// <param name="sp">The protocol to use.</param>
 protected void DownloadFile(Url url, SecureProtocol sp)
 {
     string request = GetHttpRequest(url); // holds the HTTP request for the given URL
     SecureSocket s;
     try {
         // First we create a new SecurityOptions instance
         // SecurityOptions objects hold information about the security
         // protocols the SecureSocket should use and how the SecureSocket
         // should react in certain situations.
         SecurityOptions options = new SecurityOptions(sp);
         // The Certificate field holds a certificate associated with
         // a client [you, for instance]. Because client certificates
         // are not often used for HTTP over SSL or TLS, we'll simply
         // set this field to a null reference.
         options.Certificate = null;
         // The Entity specifies whether the SecureSocket should act
         // as a client socket or as a server socket. In this case,
         // it should act as a client socket.
         options.Entity = ConnectionEnd.Client;
         // The CommonName field specifies the name of the remote
         // party we're connecting to. This is usually the domain name
         // of the remote host.
         options.CommonName = url.Host;
         // The VerificationType field specifies how we intend to verify
         // the certificate. In this case, we tell the SecureSocket that
         // we will manually verify the certificate. Look in the documentation
         // for other options.
         options.VerificationType = CredentialVerification.Manual;
         // When specifying the CredentialVerification.Manual option, we
         // must also specify a CertVerifyEventHandler delegate that will
         // be called when the SecureSocket receives the remote certificate.
         // The Verifier field holds this delegate. If no manual verification
         // is done, this field can be set to a null reference.
         options.Verifier = new CertVerifyEventHandler(OnVerify);
         // The Flags field specifies which flags should be used for the
         // connection. In this case, we will simply use the default behavior.
         options.Flags = SecurityFlags.Default;
         // Allow only secure ciphers to be used. If the server only supports
         // weak encryption, the connections will be shut down.
         options.AllowedAlgorithms = SslAlgorithms.SECURE_CIPHERS;
         // create a new SecureSocket instance and initialize it with
         // the security options we specified above.
         s = new SecureSocket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp, options);
         // connect to the remote host
         s.Connect(new IPEndPoint(Dns.GetHostEntry(url.Host).AddressList[0], url.Port));
     } catch (Exception e) {
         Console.WriteLine("Exception occurred while connecting: " + e.ToString());
         return;
     }
     // send the HTTP request to the remote host
     Console.Write("HTTP Query string:\r\n------------------\r\n" + request);
     try {
         byte[] reqBytes = Encoding.ASCII.GetBytes(request);
         int sent = s.Send(reqBytes, 0, reqBytes.Length, SocketFlags.None);
         while(sent != reqBytes.Length) {
             sent += s.Send(reqBytes, sent, reqBytes.Length - sent, SocketFlags.None);
         }
     } catch (Exception e) {
         Console.WriteLine("Exception occurred while sending: " + e.ToString());
         return;
     }
     // receive the reply
     Console.WriteLine("HTTP Server reply:\r\n------------------");
     try {
         byte[] buffer = new byte[4096];
         int ret = s.Receive(buffer);
         while(ret != 0) {
             Console.Write(Encoding.ASCII.GetString(buffer, 0, ret));
             ret = s.Receive(buffer);
         }
     } catch (Exception e) {
         Console.WriteLine("Exception occurred while receiving: " + e.ToString());
         return;
     }
     try {
         s.Shutdown(SocketShutdown.Both); // shut down the TCP connection
     } catch (Exception e) {
         Console.WriteLine("Exception occurred while shutting the connection down: " + e.ToString());
         return;
     }
     s.Close();
 }