Core_Ftp::connect

protected function connect()
{

	if (false === ($this->_conn_id = @ftp_connect($this->hostname, $this->port)))
	{
		if (IS_DEBUG)
		{
			Core::debug()->error(__('ftp unable to connect'));
		}
		return false;
	}

	if (!$this->_login())
	{
		if (IS_DEBUG)
		{
			Core::debug()->error(__('ftp unable to login'));
		}
		return false;
	}

	// 设置被动模式
	if (true===$this->passive)
	{
		ftp_pasv($this->_conn_id, true);
	}

	if ($this->path)
	{
	    $this->changedir($this->path);
	}

	return true;
}