* @throws CrawlingAccessException if the FTP request failed
     */
    private void validateRequest(final FTPClient client) {
        final int replyCode = client.getReplyCode();
        if (replyCode >= 200 && replyCode < 300) {
            return;
        }
        throw new CrawlingAccessException("Failed FTP request: " + client.getReplyString().trim());
    }

    /**