Just as a side note, I've seem anti-spambots 'captcha systems' (just see, not implemented, nor know about a library that implement it) that use a dual factor approach: one that you see and one that you know.

Indeed very simple: show an image and ask something about it.
Questions can be: type just the letters, type just the numbers, type numbers and letters in pre-defined order (left-to-right,up-down,etc), number of colors, of groups, color on the booton right, etc... The combination are limited on the imagination. And the best: it increment in exponential the way bots have to work.

Does anybody knows a library/system that implement such approach not all of them, but at least part of it?

Edson.

Em 01/04/2013 06:27, Daniel-Constantin Mierla escreveu:

Hello,

as of yesterday, creation of new accounts for Kamailio's wiki site
requires to answer a project related question. Captcha was useless as
spam bots were lately going through it easily, creating accounts in a
rate of approx 50 new registrations per day.

The extra question is asked just after CAPTCHA, see it at:
- https://www.kamailio.org/wiki/start?do=register

Hopefully the questions are simple enough to allow good people to
register and difficult enough for spambots to give up. It is not a very
sophisticated system, let's see if there will be any efforts in reverse
engineering to break in with bots. So far no new spammer account. If
they will succeed, at least they learn something useful.

If anyone has difficulties creating wiki accounts, write an email to
sr-dev mailing list and it will be investigated.

Cheers,
Daniel

PS. This registration system will last, is not for April 1.

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