Just because a user has succeeded at the captcha does not mean he is
indeed human. It's been proven by various researchers that beating
captchas is entirely possible. Optical character recognition, like that
used in flatbed scanner software, can be used with a fairly high success
rate. Another technique is to build expert systems to evaluate the
images. Another still is to build a map of hashes corresponding to
captcha images with the solutions as
value.
Getting rid of spammers is a real pain. Captchas, IP bans and user
registration limits all help but nothing really prevents it.
Registration confirmation by humans is, unfortunately, the only way to
be certain but not particularly convenient. The only thing I can think
of that might work better is to build a filter layer into editing pages
that scans the edit for words like "cialis" and if they are present
sends an email to system administrators to confirm the edit. This would
allow people to occasionally use banned words in legitimate uses but
also flag spammers very quickly.
René
Markus Neteler a écrit :
On Sun, Jul 5, 2009 at 3:02 PM, Anne Ghisla<a.ghi...@gmail.com> wrote:
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Dave Patton ha scritto:
...
There is a MediaWiki Extension for reCaptcha [1]
http://recaptcha.net/plugins/mediawiki/
[1]
http://recaptcha.net/learnmore.html
http://en.wikipedia.org/wiki/ReCAPTCHA
It is already active on new user registration, so maybe part of the spam
comes from human beings :S, then another way to limitate such spam is
ConfirmAccout extension [0], that requires sysops to confirm new users
one by one. This is extra load - but removing spam is extra load as well.
One am one of them - please don't :)
I am dealing with Wikis for many years. These human spammers always
went away so far after a period. The overhead to manually delete a page
from time to time is much less than confirming manually new users (which
is also a non-incentive since they cannot start to hack the Wiki right
away...). I don't mind to continue to delete those spam pages manually.
Cheers
Markus
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