Recently I was writing about my dislike of crawlers. They turned into a kind of necessary evil on the web – but it’s not too late to choose a different future for Gemini. I want to encourage all server authors and crawler authors to think long and hard about alternatives.
One feature I dislike about crawlers is that they follow all the links. Sure, we have a semi-useful “robots.txt” specification but it’s easy to get wrong on both sides. I’ve had bugs in my “robots.txt” file for a long time without noticing them.
Now, if the argument is that I cannot prevent crawlers from leeching my site, then the reply is of course that I will try to defend myself even if it is impossible to get 100% right. The first line of defence is going to be my “robots.txt” file. It’s not perfect, and that’s fine. It’s not perfect because I just need to look at the Apache config file I use to block all the misbehaving bots and user agents.
Ugh, look at the bots hitting my websites:
$ /home/alex/bin/bot-detector < /var/log/apache2/access.log.1 --------------Bandwidth-------Hits-------Actions--Delay Everybody 2416M 102520 All Bots 473M 23063 100% 19% ------------------------------------------------------- bingbot 240836K 8157 35% 31% 10s YandexBot 36279K 3905 16% 3% 22s Googlebot 65808K 3679 15% 34% 23s Adsbot 20187K 3115 13% 0% 27s Applebot 66607K 908 3% 0% 95s Facebot 1611K 390 1% 0% 220s PetalBot 1548K 329 1% 12% 257s Bot 2101K 308 1% 0% 280s robots 525K 231 1% 0% 374s Slackbot 1339K 224 0% 96% 382s SemrushBot 572K 194 0% 0% 438s
A full 22% of all user agents have something like “bot” in their name. Just look at them! Let’s take the last one, SemrushBot. The user agent also has a link, and if you want, you can take a look. All the goals it lists are disgusting, or benefit corporations and not me, nor other humans. Barf with me as you read statements such as “the Brand Monitoring tool to index and search for articles” or “the On Page SEO Checker and SEO Content template tools reports”. 🤮
Have a look at your own webserver logs. 22% of my CPU resources, of the CO₂ my server produces, of the electricity it eats, for machines that do not have my best interest in mind. I don’t want a web that’s 20% bots crawling all over my site. I don’t want a Gemini space that’s 20% bots crawling all over my capsules.
OK, so let’s talk about defence.
When I look at my Gemini logs, I see that plenty of requests come from Amazon hosts. I take that as a sign of autonomous agents. I might sound like a fool on the Butlerian Jihad, but if I need to block entire networks, then I will. Looking up WHOIS data also costs resources. It would be better if we could identify these bots by looking at their behaviour.
The first mistake crawlers make is that they are too fast. So here’s what I’m currently doing: for every IP, I’m keeping track of the last 30 requests in the last 60s. If there are more requests, the IP number is blocked. Thus, if your average clicking rate is more than 1 click per 2s over a 1min window, you’re probably a bot and you get blocked. I might have to turn this up. Perhaps 1 click per 5s makes more sense for a human.
But there’s more. I see the crawlers clicking on all the links. All the HTML renderings of the pages are already available via Gemini. It makes no sense to request all of these. All the raw wiki text of the pages are available as well. It makes no sense to request all of these, either. All the links to leave a comment are also on every page. It makes no sense to request all of these either.
Here’s what I’m talking about. I picked an IP number from the logs and checked what they’ve been requesting:
2020-12-25 08:32:37 gemini://transjovian.org:1965/page/Linking/2 2020-12-25 08:32:45 gemini://alexschroeder.ch:1965/history/Perl 2020-12-25 08:32:59 gemini://communitywiki.org:1965/page/CategoryWikiProcess 2020-12-25 08:33:18 gemini://transjovian.org:1965/page/Titan/5 2020-12-25 08:33:30 gemini://communitywiki.org/page/CultureOrganis%C3%A9e 2020-12-25 08:33:57 gemini://transjovian.org:1965/history/Spaces 2020-12-25 08:34:23 gemini://transjovian.org:1965/gemini/page/common%20wiki%20structure/TimurIsmagilov 2020-12-25 08:34:30 gemini://alexschroeder.ch:1965/tag/Hex%20Describe 2020-12-25 08:34:56 gemini://communitywiki.org:1965/page/SoftwareBazaar 2020-12-25 08:35:02 gemini://communitywiki.org:1965/page/DoTank 2020-12-25 08:35:22 gemini://transjovian.org:1965/test/history/Welcome 2020-12-25 08:36:56 gemini://alexschroeder.ch:1965/tag/Gadgets 2020-12-25 08:38:20 gemini://alexschroeder.ch:1965/tag/Games 2020-12-25 08:45:58 gemini://alexschroeder.ch:1965/do/comment/GitHub 2020-12-25 08:46:05 gemini://alexschroeder.ch:1965/html/GitHub 2020-12-25 08:46:12 gemini://alexschroeder.ch:1965/raw/Comments_on_GitHub 2020-12-25 08:46:19 gemini://alexschroeder.ch:1965/raw/GitHub 2020-12-25 08:47:45 gemini://alexschroeder.ch:1965/page/2018-08-24_GitHub 2020-12-25 08:47:51 gemini://alexschroeder.ch:1965/do/comment/Comments_on_2018-08-24_GitHub 2020-12-25 08:47:57 gemini://alexschroeder.ch:1965/html/Comments_on_2018-08-24_GitHub 2020-12-25 09:21:26 gemini://alexschroeder.ch:1965/do/more
See what I mean? This is not a human. This is an unsupervised bot, otherwise the operator would have discovered that this makes no sense.
The solution I’m using for my websites is logging IP numbers and using fail2ban to ban IP numbers that request too many pages. The ban is for 10min, and if you’re a “recidive”, meaning you got banned three times for 10min, then you’re going to be banned for a week. The problem I have is that I would prefer a solution that doesn’t log IP numbers. It’s good for privacy and we should write our software such that privacy comes first.
So I wrote a Phoebe extension called “speed bump”. Here’s what it currently does.
For every IP number, Phoebe records the last 30 requests in the last 60 seconds. If there are more than 30 requests in the last 60 seconds, the IP number is blocked. If somebody is faster on average than two seconds per request, I assume it’s a bot, not a human.
For every IP number, Phoebe records whether the last 30 requests were suspicious or not. A suspicious request is a request that is “disallowed” for bots according to “robots.txt” (more or less). If 10 requests or more of the last 30 requests in the last 60 seconds are suspicious, the IP number is also blocked. That is, even if somebody is as slow as three seconds per request, if they’re all suspicious, I assume it’s a bot, not a human.
When an IP number is blocked, it is blocked for 60s, and there’s a 120s probation time. When you’re blocked, Phoebe responds with a “44” response. This means: slow down!
If the IP number sends another request while it is blocked, or if it gives cause for another block in the probation time, it is blocked again and the blocking time is doubled: the IP is blocked for 120s and probation is extended by 240s. And if it happens again, it is doubled again: blocked for 240s and probabation is extended by 480s.
The “/do/speed-bump/debug” URL (which requires a known client certificate) shows you the raw data, and the “/do/speed-bump/status” URL (which also requires a known client certificate) shows you a human readable summary of what’s going on.
Here’s an example:
Speed Bump Status From To Warns Block Until Probation IP n/a n/a 0/ 0 60s n/a 100m 188.8.131.52 n/a n/a 0/ 0 60s 4h 14h 184.108.40.206 n/a n/a 0/ 0 60s n/a 9h 220.127.116.11 -280s -1s 7/30 n/a n/a n/a 18.104.22.168
All four of these numbers belong to “Amazon Data Services UK”.
If there are numbers in the “From” and “To” columns, that means the IP made a request in the last 60s. The “Warns” column says how many of the requests were considered “suspicious”. “Block” is the block time. As you can see, none of the bots managed to increase the block time. Why is that? The “Probation” column offers a glimpse into what happened: as the bots kept making requests while they were blocked, they kept adding to their own block.
A bit later:
Speed Bump Status From To Warns Block Until Probation IP n/a n/a 0/ 0 60s n/a 83m 22.214.171.124 n/a n/a 0/ 0 60s 4h 13h 126.96.36.199 n/a n/a 0/ 0 60s n/a 9h 188.8.131.52 -219s -7s 3/30 n/a n/a n/a 184.108.40.206
It seems that the last IP number is managing to thread the line.
Clearly, this is all very much in flux. I’m still working on it – and finding bugs in my “robots.txt”, unfortunately. I’ll keep this page updated as I learn more. One idea I’ve been thinking about is the time windows: how many pages would an enthusiastic human read on a new site: 60 pages in an hour, one minute per page? Or maybe twice as much? That would point towards keeping a counter for a long term average: if you’re requesting more than 60 pages in 30min, perhaps a timeout of 30min is appropriate?
The smol net is also a slow net. There’s no need for almost all activity to be crawlers. If at all, crawlers should be the minority! So, if my sites had 95% human activity and 5% robot activity, I’d be more understanding. But right now, it’s crazy. All the CO₂ wasted, for bots.
I’m on The Butlerian Jihad!