3 ms·

The problem with scrapers in general is the asymmetry of compute resources involved in generating versus requesting a website. You can likely make millions of

The problem with scrapers in general is the asymmetry of compute resources involved in generating versus requesting a website. You can likely make millions of HTTP requests with the compute required in generating the average response. If you make it more expensive to request a documents at scale, you make this type of crawling prohibitively expensive. On a small scale it really doesn't matter, but if you're casting an extremely wide net and re-fetching the same documents hundreds of times, yeah it really does matter. Even if you have a big VC budget.

charcircuit 2y ago
If you make it prohibitively expensive almost no regular user will want to wait for it.
- bobmcnamara 2y ago
  Exponential backoff!
- xboxnolifes 2y ago
  Regular users usually aren't page hopping 10 pages per second. A regular user is usually 100 times less than that.
  - pabs3 2y ago
    I tend to get blocked by HN when opening lots of comment pages in tabs with Ctrl+click.
    - xboxnolifes 2y ago
      Yes, HN has a fairly strict slow down policy for commenting. But, that's irrelevant to the context.
      - pabs3 2y ago
        I meant to say article pages not comment pages, but ack.
Nathanba 2y ago
Yes but the scraper only has to solve it once and it gets cached too right? Surely it gets cached, otherwise it would be too annoying for humans on phones too? I guess it depends on whether scrapers are just simple curl clients or full headless browsers but I seriously doubt that Google tier LLM scrapers rely on site content loading statically without js.
- Hakkin 2y ago
  It sets a cookie with a JWT verifying you completed the proof-of-work along with metadata about the origin of the request, the cookie is valid for a week. This is as far as Anubis goes, once you have this cookie you can do whatever you want on the site. For now it seems like enough to stop a decent portion of web crawlers. You can do more underneath Anubis using the JWT as a sort of session token though, like rate limiting on a per proof-of-work basis, if a client using X token makes more than Y requests in a period of time, invalidate the token and force them to generate a new one. This would force them to either crawl slowly or use many times more resources to crawl your content.
- ndiddy 2y ago
  AI companies have started using a technique to evade rate limits where they will have a swarm of tens of thousands of scraper bots using unique residential IPs all accessing your site at once. It's very obvious in aggregate that you're being scraped, but when it's happening, it's very difficult to identify scraper vs. non-scraper traffic. Each time a page is scraped, it just looks like a new user from a residential IP is loading a given page. Anubis helps combat this because even if the scrapers upgrade to running automated copies of full-featured web browsers that are capable of solving the challenges (which means it costs them a lot more to scrape than it currently does), their server costs would balloon even further because each time they load a page, it requires them to solve a new challenge. This means they use a ton of CPU and their throughput goes way down. Even if they solve a challenge, they can't share the cookie between bots because the IP address of the requestor is used as part of the challenge.
  - Nathanba 2y ago
    Tens of thousands of scraper bots for a single site? Is that really the case? I would have assumed that maybe 3-5 bots send lets say 20 requests per second in parallel to scrape. Sure, they might eventually start trying different ips and bots if their others are timing out but ultimately it's still the same end result: All they will realize is that they have to increase the timeout and use headless browsers to cache results and the entire protection is gone. But yes, I think for big bot farms it will be a somewhat annoying cost increase to do this. This should really be combined with the cloudflare captcha to make it even more effective.

charcircuit 2y ago

If you make it prohibitively expensive almost no regular user will want to wait for it.

bobmcnamara 2y ago
Exponential backoff!
xboxnolifes 2y ago
Regular users usually aren't page hopping 10 pages per second. A regular user is usually 100 times less than that.
- pabs3 2y ago
  I tend to get blocked by HN when opening lots of comment pages in tabs with Ctrl+click.
  - xboxnolifes 2y ago
    Yes, HN has a fairly strict slow down policy for commenting. But, that's irrelevant to the context.
    - pabs3 2y ago
      I meant to say article pages not comment pages, but ack.

Nathanba 2y ago

Yes but the scraper only has to solve it once and it gets cached too right? Surely it gets cached, otherwise it would be too annoying for humans on phones too? I guess it depends on whether scrapers are just simple curl clients or full headless browsers but I seriously doubt that Google tier LLM scrapers rely on site content loading statically without js.

Hakkin 2y ago
It sets a cookie with a JWT verifying you completed the proof-of-work along with metadata about the origin of the request, the cookie is valid for a week. This is as far as Anubis goes, once you have this cookie you can do whatever you want on the site. For now it seems like enough to stop a decent portion of web crawlers. You can do more underneath Anubis using the JWT as a sort of session token though, like rate limiting on a per proof-of-work basis, if a client using X token makes more than Y requests in a period of time, invalidate the token and force them to generate a new one. This would force them to either crawl slowly or use many times more resources to crawl your content.
ndiddy 2y ago
AI companies have started using a technique to evade rate limits where they will have a swarm of tens of thousands of scraper bots using unique residential IPs all accessing your site at once. It's very obvious in aggregate that you're being scraped, but when it's happening, it's very difficult to identify scraper vs. non-scraper traffic. Each time a page is scraped, it just looks like a new user from a residential IP is loading a given page. Anubis helps combat this because even if the scrapers upgrade to running automated copies of full-featured web browsers that are capable of solving the challenges (which means it costs them a lot more to scrape than it currently does), their server costs would balloon even further because each time they load a page, it requires them to solve a new challenge. This means they use a ton of CPU and their throughput goes way down. Even if they solve a challenge, they can't share the cookie between bots because the IP address of the requestor is used as part of the challenge.
- Nathanba 2y ago
  Tens of thousands of scraper bots for a single site? Is that really the case? I would have assumed that maybe 3-5 bots send lets say 20 requests per second in parallel to scrape. Sure, they might eventually start trying different ips and bots if their others are timing out but ultimately it's still the same end result: All they will realize is that they have to increase the timeout and use headless browsers to cache results and the entire protection is gone. But yes, I think for big bot farms it will be a somewhat annoying cost increase to do this. This should really be combined with the cloudflare captcha to make it even more effective.