/// <summary>
        /// Creates a remote TCP connection through a proxy server to the destination host on the destination port.
        /// </summary>
        /// <param name="destinationHost">Destination host name or IP address.</param>
        /// <param name="destinationPort">Port number to connect to on the destination host.</param>
        /// <param name="timeout">Timeout duration for the Connect attempt.</param>
        /// <returns>
        /// Returns an open TcpClient object that can be used normally to communicate
        /// with the destination server
        /// </returns>
        /// <remarks>
        /// This method creates a connection to the proxy server and instructs the proxy server
        /// to make a pass through connection to the specified destination host on the specified
        /// port.  
        /// </remarks>
        public TcpClient CreateConnection(string destinationHost, int destinationPort, TimeSpan timeout)
        {
            try
            {
                // if we have no connection, create one
                if (TcpClient == null)
                {
                    if (string.IsNullOrEmpty(ProxyHost))
                        throw new ProxyException("ProxyHost property must contain a value.");

                    if (ProxyPort <= 0 || ProxyPort > 65535)
                        throw new ProxyException("ProxyPort value must be greater than zero and less than 65535");

                    //  create new tcp client object to the proxy server
                    TcpClient = tcpClientFactory();

                    // attempt to open the connection
                    log.Write(EventType.Diagnostic, "Connecting to proxy at {0}:{1}", ProxyHost, ProxyPort);
                    TcpClient.ConnectWithTimeout(ProxyHost, ProxyPort, timeout);
                }

                //  send connection command to proxy host for the specified destination host and port
                SendConnectionCommand(destinationHost, destinationPort);

                // return the open proxied tcp client object to the caller for normal use
                return TcpClient;
            }
            catch (SocketException ex)
            {
                throw new ProxyException(string.Format(CultureInfo.InvariantCulture, "Connection to proxy host {0} on port {1} failed.", Utils.GetHost(TcpClient), Utils.GetPort(TcpClient)), ex);
            }
        }