npm package discovery and stats viewer.

Discover Tips

  • General search

    [free text search, go nuts!]

  • Package details

    pkg:[package-name]

  • User packages

    @[username]

Sponsor

Optimize Toolset

I’ve always been into building performant and accessible sites, but lately I’ve been taking it extremely seriously. So much so that I’ve been building a tool to help me optimize and monitor the sites that I build to make sure that I’m making an attempt to offer the best experience to those who visit them. If you’re into performant, accessible and SEO friendly sites, you might like it too! You can check it out at Optimize Toolset.

About

Hi, 👋, I’m Ryan Hefner  and I built this site for me, and you! The goal of this site was to provide an easy way for me to check the stats on my npm packages, both for prioritizing issues and updates, and to give me a little kick in the pants to keep up on stuff.

As I was building it, I realized that I was actually using the tool to build the tool, and figured I might as well put this out there and hopefully others will find it to be a fast and useful way to search and browse npm packages as I have.

If you’re interested in other things I’m working on, follow me on Twitter or check out the open source projects I’ve been publishing on GitHub.

I am also working on a Twitter bot for this site to tweet the most popular, newest, random packages from npm. Please follow that account now and it will start sending out packages soon–ish.

Open Software & Tools

This site wouldn’t be possible without the immense generosity and tireless efforts from the people who make contributions to the world and share their work via open source initiatives. Thank you 🙏

© 2024 – Pkg Stats / Ryan Hefner

reverse-dns-lookup

v2.1.0

Published

🕵 Verify an IP is related to a certain domain

Downloads

435

Readme

reverse-dns-lookup

🕵 Verify an IP is related to a certain domain

You can verify if a web crawler accessing your server really is who they claim they are. This is useful if you're concerned that spammers or other troublemakers are accessing your site while claiming to be known crawlers. Crawlers do not post public lists of IP addresses to whitelist. This is because these IP address ranges can change, causing problems for any systems who have hard-coded them, so you must run a DNS lookup as described next.

Example flow to verify Googlebot as the caller

import { verify } from "reverse-dns-lookup";
import requestIP from "request-ip";

const clientIp = requestIP.getClientIp(request);
const isGooglebotServer = await verify(clientIp, "google.com", "googlebot.com");

What just happened?

  1. Run a reverse DNS lookup on the accessing IP address.
  2. Verify that the domain name is in the supplied domain names.
  3. Run a forward DNS lookup on the retrieved domain name (from step 1).
  4. Verify that it is the same as the original accessing IP address from your logs.

Some popular domains

const crawler_domains = [
  ".google.com",
  ".googlebot.com",
  "search.msn.com", // Bing
  ".applebot.apple.com",
  ".twttr.com", // Twitter
  ".crawl.baidu.com", // Baidu craler
];

const isCrawlerServer = await verify(clientIp, ...crawler_domains);

CLI

reverse-dns-lookup 66.249.66.1 google.com googlebot.com

| Checks out | - | 66.249.66.1 checks up with google.com, googlebot.com | Exit code 0


| Does not check out okay | - | 1.1.1.1 does not check up with google.com, googlebot.com. | Exit code 1