public function connect($host, $ssl = false, $port = 21, $timeout = 90)
    {
        if ($ssl) {
            $this->conn = @$this->ftp->ssl_connect($host, $port, $timeout);
        } else {
            $this->conn = @$this->ftp->connect($host, $port, $timeout);
        }
        if (!$this->conn) {
            throw new FtpException('Unable to connect');
        }

        return $this;
    }