[mdasher]

We're not dealing with 99 ASs blocking another bad actor. We're talking about one service that sits in front of many popular services on the internet deciding to block another for dubious reasons. Cloudflare has near monopoly power here.

[nucleardog]

I guess I look at it differently - every site using CloudFare made the decision to delegate their web security to them. I don't see it as "one entity blocking another" but "all of those individual sites blocking a single network".

In that context, it's a lot of votes for Tor to find a solution to this problem.

Really, I'm surprised at CloudFare's restraint here. A lot of their customers probably couldn't care less about Tor, but they've been putting a lot of effort into trying to avoid blocking Tor users (actually blocking, not inconveniencing) or compromising their anonymity.

[zzzcpan]

Developers care and they are very important to Cloudflare. It is in their best interest to actually do it properly.

[comex]

That's exactly the problem: customers who don't care.

Based on what I've seen in the thread of the bug report that spawned this debate, most of the browsing activity that these CAPTCHAs get in the way of is read-only. The only ways (nominally) read-only requests can cause harm are DDOS and exploiting vulnerabilities in the server software. Tor doesn't have enough bandwidth to be a big contributor to a DDOS, and sticking CAPTCHAs before some users is at best a probabilistic solution, as it only avoids exploits that:

(a) are untargeted (scanning the whole internet - if a human attacker cared about your site in particular then they could easily switch to one of the following methods to circumvent the CAPTCHA);

(b) use Tor rather than going to more effort to get access to less tainted IPs (VPS, botnets...) - assuming that the attack itself doesn't gather bad reputation (in cases where CloudFlare can detect malicious traffic by inspection, it can do better than IP blocking);

(c) don't use a service that farms CAPTCHA solving out to humans - which increases the attacker's cost but not by much.

Since the harm reduction is so minor, I suspect that for most sites, if the administrators had even a small incentive to support Tor users and the time to think about it, they would not choose CloudFlare's coarse-grained CAPTCHA approach. Rather, they'd make sure to have their own CAPTCHAs before anonymous write actions and before user registration - which they should be doing anyway - and leave read-only access alone. And the benefits of Tor to users in repressive countries should be enough to provide that small incentive, if they cared.

But they don't care. They don't want to change anything (like adding CAPTCHAs) unless there's a problem, and if CloudFlare can reduce that problem without their having to think about it, then that's the path of least resistance and they'll go with it even if there are consequences. I suspect most site owners, if asked about Tor, would say "just block it", which is why CloudFlare has - admirably - gone out of its way to doing so in its UI difficult. This is (a large portion of) who CloudFlare represents and I agree with you that they're showing restraint.

But here's where I differ: I don't think mass apathy counts as "votes for Tor to find a solution to this problem". While the magnitude of harm is of course completely different, that's like saying that in the case of discrimination against a minority group, since most majority group members just want the issue to go away, they're voting for the minority to "find a solution" - when the only real solution is for the majority to change and stop discriminating. I mean, maybe they will vote that way in actual elections, but apathy votes don't reflect the "wisdom of the crowd" as much as others do; the minority shouldn't just consider themselves overruled and give up.

CloudFlare is already "defying" those votes to some extent, and if there is no good solution that can make both parties happy, I'd say it would be the right thing to do for them to go a little further and open up a little more for Tor users, even if it's not what their customers would decide in a knee-jerk reaction. I hope that this blinded CAPTCHA idea will turn out to be such a solution, though. It's not ideal, since having any kind of CAPTCHA blocks potentially-legitimate automated traffic, but I think it's a good enough compromise for now - sites that care could still turn it off entirely. I hope the Tor developers won't let the perfect be the enemy of the good.

Oh, and - I think there is one act for which CloudFlare deserves some blame: signing up those customers in the first place with the promise to provide "security" at the CDN level. It's not that what they do is useless, but given the fundamental limits of (all) "web application firewalls" that only see the application from the outside and thus can only guess heuristically what is an attack, less technical customers are probably misled somewhat about the necessity and benefit of them. Most people, including less technical site administrators or owners, don't even understand the difference between DDOS and "real" attacks, let alone what WAFs do or, say, what concerns apply to Tor in particular. I'm not sure what CF could do to fix this short of not advertising security at all, and that would undersell what they do provide. Even so...