[fc417fc802]

Supposedly, but not really. I regularly encounter sites where cloudflare serves me with an ambiguous ban notice rather than a proof of work. What's worse is that these apparent IP bans take effect even if I already had a valid active session (ie previously passed the check).

Yes, a VPN involved. That doesn't make it okay and notice that anubis by default works without issue (though possibly with a more difficult challenge) in the exact same scenario.

[alightsoul]

There's lists of data center IPs. You're probably in them and That's why you're getting banned

[fc417fc802]

Regardless of the precise logic it's no excuse for the policy. Simply hand out a sufficiently difficult PoW to prevent widespread abuse.

I'm quite certain it isn't a generic "datacenter" list though because a given VPN exit that was working will suddenly stop. Meanwhile I have a valid cookie yet that is disregarded.

[alightsoul]

Wikipedia maintains a quite exhaustive list of them to prevent spam and they also block vpn IPs as soon as they're found.

[fc417fc802]

That is an entirely different matter. They only block (AFAIK) editing which is a scenario where PoW would not be expected to solve the problem. What I was talking about here is IP banning as a (boneheaded) mitigation against high volume scrapers.