Verify by reverse DNS of crawlers identity

crawlerip.js

const { reverse } = require('dns')

const check = ip => new Promise(
	(resolve, reject) =>
		addresses.includes(ip) || reverse(
			ip,
			(error, hostnames) => error
				? reject(error)
				: resolve(
						hostnames.some(
							hostname => pattern.test(hostname)
						)
					)
		)
);

const BAIDU = '\\.crawl\\.baidu\\.(com|jp)$';
const BING = '\\.search\\.msn\\.com$';
const GOOGLE = '\\.google(bot)?\\.com$';
const YAHOO = '\\.crawl\\.yahoo\\.net$';
const YANDEX = '\\.yandex\\.(ru|net|com)$';

// whois -h whois.radb.net -- '-i origin AS32934' | grep ^route  
const FACEBOOK = [];
// whois -h whois.radb.net — '-i origin AS13414' | grep ^route
const TWITTER = [];
// https://duckduckgo.com/duckduckbot 
const DUCKDUCKGO = [
	'72.94.249.34',
	'72.94.249.35',
	'72.94.249.36',
	'72.94.249.37',
	'72.94.249.38'
];

const pattern = new RegExp([
	BAIDU,
	BING,
	GOOGLE,
	YAHOO,
	YANDEX
].join('|'));

const addresses = [
	FACEBOOK,
	TWITTER,
	DUCKDUCKGO
].flat()

// Example
const isCrawler = await check('66.249.69.45');