private async void StartSSL()
        {
            RemoteCertificateValidationCallback sslValidateCallback =
                new RemoteCertificateValidationCallback(ServerCheckValidation);
            SslStream ss = new SslStream(baseStream, true, sslValidateCallback, null);
            X509CertificateCollection certs = GetClientCertificates();
            await ss.AuthenticateAsClientAsync(Settings.Server, certs, SslProtocols.Tls | SslProtocols.Tls11 | SslProtocols.Tls12, false);
            baseStream = ss;
            stream = new MySqlStream(ss, Encoding, false);
            stream.SequenceByte = 2;

        }
        public void Close(bool isOpen)
        {
            try
            {
                if (isOpen)
                {
                    try
                    {
                        packet.Clear();
                        packet.WriteByte((byte)DBCmd.QUIT);
                        ExecutePacket(packet);
                    }
                    catch (Exception)
                    {
                        // Eat exception here. We should try to closing 
                        // the stream anyway.
                    }
                }

                if (stream != null)
                    stream.Close();
                stream = null;
            }
            catch (Exception)
            {
                // we are just going to eat any exceptions
                // generated here
            }
        }
        public void Open()
        {
            // connect to one of our specified hosts
            try
            {
                baseStream = StreamCreator.GetStream(Settings);
#if NET451
         if (Settings.IncludeSecurityAsserts)
            MySqlSecurityPermission.CreatePermissionSet(false).Assert();
#endif
            }
            catch (System.Security.SecurityException)
            {
                throw;
            }
            catch (Exception ex)
            {
                throw new MySqlException(Resources.UnableToConnectToHost,
                    (int)MySqlErrorCode.UnableToConnectToHost, ex);
            }
            if (baseStream == null)
                throw new MySqlException(Resources.UnableToConnectToHost,
                    (int)MySqlErrorCode.UnableToConnectToHost);

            int maxSinglePacket = 255 * 255 * 255;
            stream = new MySqlStream(baseStream, Encoding, false);

            stream.ResetTimeout((int)Settings.ConnectionTimeout * 1000);

            // read off the welcome packet and parse out it's values
            packet = stream.ReadPacket();
            int protocol = packet.ReadByte();
            string versionString = packet.ReadString();
            owner.isFabric = versionString.EndsWith("fabric", StringComparison.OrdinalIgnoreCase);
            version = DBVersion.Parse(versionString);
            if (!owner.isFabric && !version.isAtLeast(5, 0, 0))
                throw new NotSupportedException(Resources.ServerTooOld);
            threadId = packet.ReadInteger(4);
            encryptionSeed = packet.ReadString();

            maxSinglePacket = (256 * 256 * 256) - 1;

            // read in Server capabilities if they are provided
            ClientFlags serverCaps = 0;
            if (packet.HasMoreData)
                serverCaps = (ClientFlags)packet.ReadInteger(2);

            /* New protocol with 16 bytes to describe server characteristics */
            owner.ConnectionCharSetIndex = (int)packet.ReadByte();

            serverStatus = (ServerStatusFlags)packet.ReadInteger(2);

            // Since 5.5, high bits of server caps are stored after status.
            // Previously, it was part of reserved always 0x00 13-byte filler.
            uint serverCapsHigh = (uint)packet.ReadInteger(2);
            serverCaps |= (ClientFlags)(serverCapsHigh << 16);

            packet.Position += 11;
            string seedPart2 = packet.ReadString();
            encryptionSeed += seedPart2;

            string authenticationMethod = "";
            if ((serverCaps & ClientFlags.PLUGIN_AUTH) != 0)
            {
                authenticationMethod = packet.ReadString();
            }
            else
            {
                // Some MySql versions like 5.1, don't give name of plugin, default to native password.
                authenticationMethod = "mysql_native_password";
            }

            // based on our settings, set our connection flags
            SetConnectionFlags(serverCaps);

            packet.Clear();
            packet.WriteInteger((int)connectionFlags, 4);
            
            if ((serverCaps & ClientFlags.SSL) == 0)
            {
                if ((Settings.SslMode != MySqlSslMode.None)
                && (Settings.SslMode != MySqlSslMode.Preferred))
                {
                    // Client requires SSL connections.
                    string message = String.Format(Resources.NoServerSSLSupport,
                        Settings.Server);
                    throw new MySqlException(message);
                }
            }
            else if (Settings.SslMode != MySqlSslMode.None)
            {
                stream.SendPacket(packet);
                StartSSL();
                packet.Clear();
                packet.WriteInteger((int)connectionFlags, 4);
            }
            
            packet.WriteInteger(maxSinglePacket, 4);
            packet.WriteByte(8);
            packet.Write(new byte[23]);

            Authenticate(authenticationMethod, false);

            // if we are using compression, then we use our CompressedStream class
            // to hide the ugliness of managing the compression
            if ((connectionFlags & ClientFlags.COMPRESS) != 0)
                stream = new MySqlStream(baseStream, Encoding, true);

            // give our stream the server version we are connected to.  
            // We may have some fields that are read differently based 
            // on the version of the server we are connected to.
            packet.Version = version;
            stream.MaxBlockSize = maxSinglePacket;
        }