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The Trouble with CloudFlare

blog.torproject.org

251–260 of 361 posts

Re: The Trouble with CloudFlare

#251
post #68
post #55

Earlier quoted context omitted.

Did you intend this as a reply to something else? I can't even connect your comment to what I said. It starts with "wrong" but doesn't seem to address anything I said.

Please bullet/number your concerns as self-contained statements and I'll explicitly reference them. And yes, my response is to your comment, though do see how it's possible it's ambiguous to how I'm addressing your concerns. Thanks for the comment.

It's not his job to format his comment to make it convenient for you to rebut. I agree that it's not at all clear how your reply addresses the original comment. Perhaps you could fix that by quoting the portions of the original comment you're replying to, rather than requiring line numbers.

Re: The Trouble with CloudFlare

#252

Earlier quoted context omitted.

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.

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 ab…

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...

Re: The Trouble with CloudFlare

#253
post #248
post #45

> 5) A report by CloudFlare competitor Akamai found that the percentage of legitimate e-commerce traffic originating from Tor IP addresses is nearly identical to that originating from the Internet at large. (Specifically, Akamai found that the "conversion rate" of Tor IP addresses clicking on ads and performing commercial activity was "virtually equal" to that of non-Tor IP addresses). This point seems rather odd. I'…

Is this a wording issue? > Akamai found that the "conversion rate" of Tor IP addresses clicking on ads and performing commercial activity was "virtually equal" to that of non-Tor IP addresses So when seeing actual web traffic things are identical. That only measures real web traffic. It doesn't measure all the SSH attacks, SPAM being sent, possibly checking for vulnerabilities and unpatched software/etc.

CloudFlare doesn't do anything other than web traffic. It's basically an nginx reverse proxy on steroids.

Re: The Trouble with CloudFlare

#254

Earlier quoted context omitted.

So there are two problems here, right? Spam and DoS. Comment spam isn't a CloudFlare-level problem. If sites want to allow anonymous comments then they get the consequences of anonymous comments (or have their own CAPTCHA for them); if they want to require account registration and some vouching or proof of work or payment to get an account then they can have that as well. DoS is a CloudFlare problem, but you don't ne…

Comment spam is one of the things CloudFlare advertise as protecting sites from, so yes it is their problem.

It's only their problem because they chose to claim they could solve it when their solution is the one that causes all of this trouble.

They're not in a position to do it accurately.

Re: The Trouble with CloudFlare

#255
post #60

Maybe I'm a cranky, old-school network operator, but this is a very cut and dry problem. Tor runs a network that is rife with abuse and fraud. Tor needs to clean up and police its network. If it doesn't, it will be put on blacklists and customers will take active measures to block traffic from it. This is no different than a network or AS that is spammer friendly, botnet friendly, carder friendly, etc. All of those n…

The main point of Tor is that nobody knows where the traffic comes from. Realize you're asking them to break their own service. Your premise seems to be that you can't be bothered to protect your networks so you want to put that responsibility on someone else. It's called intermediary liability and it's terrible because the intermediary has all the wrong incentives. You demand that the intermediary eliminate maliciou…

TOR exit nodes could run an IDENT-like service, that offers only a hash based on the source of the traffic... it would still be psuedo-anonymous, but easier to filter by the target of said traffic.

Re: The Trouble with CloudFlare

#256

Earlier quoted context omitted.

The main point of Tor is that nobody knows where the traffic comes from. Realize you're asking them to break their own service. Your premise seems to be that you can't be bothered to protect your networks so you want to put that responsibility on someone else. It's called intermediary liability and it's terrible because the intermediary has all the wrong incentives. You demand that the intermediary eliminate maliciou…

Google does this with Linode servers. I route my HTTP traffic through a proxy on a Linode server. Google blocks me all the time for no reason other than that some other IPs in my range are doing bad things. I've tried to contact Google about this but they could care less about a handful of users.

I've experienced the same issue from multiple service providers, including but not limited to Google, Akamai, Cloudflare, and more.

My Linode IP address was assigned to me years ago. I do not use it maliciously, do not share it with other people, and have never used it for tor. Yet find myself regularly blocked for no logical reasons when I proxy my web-request through it.

Re: The Trouble with CloudFlare

#257
post #212
post #189

Earlier quoted context omitted.

Yes, you will. But the point is, with no other information to go on, that is the best option for the website. If you don't want to be challenged constantly, you need to give the website operator some incentive to accept your traffic.

There is plenty of information to go off of. They just don't want to put in the engineering effort required to utilize it. Is there really a constant DDoS attack on all of these sites from users with no cookies?

On a given site, not necessarily, but on some sites that cloudflare is protecting, pretty much always would be my guess... cloudflare doesn't know you're not the spammer/bot/malicious actor using the same exit node... it only knows that you don't have any cookies, and that means you look a lot like the bad guys coming from the same IP.

One could setup an IDENT-like service that delivers a hash for the source's route, and that would enable better scoring, but also could be used as a tracking measure... you can't have one without the other.

Even then, it would take either the user allowing cookies, or the TOR system to change their exit nodes.

Re: The Trouble with CloudFlare

#258
post #196

Earlier quoted context omitted.

> It's like city guards banning everyone with a mask from entering and issuing IDs to them. The flaw in this analogy is that in this case the mask makes every person completely indistinguishable from every other person wearing the mask. In this case, one ID is issued to every person wearing the mask. When 90%+ of the people with this ID are criminals and vandals, blocking anyone with this ID is a pretty obvious and e…

That's a crazy thing to do. Why would you block everyone? This would completely erode privacy online. As I said elsewhere, if you see 1000 masked people rush into a bar and block the entrance with their bodies, is the solution to block all masked people from going to all establishments? Clearly, if this happened IRL, people would just put a limit on the number of masked people entering that bar until there wasn't a g…

Except tell the individuals apart and so you can't limit it to 1,000 individuals. You can't just let some in if you can't tell them apart. There is no door that works that way in this case.

It's best to imagine it's a walk-up bar rather than one with a door.

Re: The Trouble with CloudFlare

#259

Payments originating from TOR IP addresses absolutely are more likely to be fraudulent. Anyone running an online business could tell you that.

Hassling Tor users shouldn't become the Internet's default. If you're having trouble, consider informing Tor users checking out that you won't process the payment without their providing additional information. This raises the cost to carders a lot more than needing to rent a SOCKS proxy in a residential area.

It's not worth the development costs and extra verification costs to try to weed a small number of legitimate purchases from a sea of illegitimate ones though.

Re: The Trouble with CloudFlare

#260
post #247
post #167

Earlier quoted context omitted.

> Tor needs to clean up and police its network I think you don't understand what Tor is or how it works. Tor is a way to anonymize its users. You have no way to analyze a packet until it reaches an exit node, and you have no way to analyze that packet if it's done over https, and you have no way to block an ip from that exit node because it comes from another node where plenty of other ips are coming from. If you sta…

I think it's clear he understands how it works. > what you are saying goes against Tor's principals That's why it will probably never be cleaned up. That's also why more and more people will probably block access from Tor. CloudFlare says they get a 95% attack rate from it. A blog post the other day said FotoForensics gets about 91% attacks from Tor. No one is going to put up with 91% attacks for long. And if that me…

> I think it's clear he understands how it works.

Agree to disagree :)

> if that means Tor becomes it's own walled garden that doesn't 'interact' with the public internet, so be it

Most websites are not using Cloudflare and have no idea how to block a range of ips. So no Tor is not going to become its own walled garden.

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