Extension:ReCAPTCHA

What can this extension do?
reCAPTCHA places a strong CAPTCHA on your wiki. The CAPTCHA helps to read books that are scanned by projects such as archive.org. The CAPTCHA also includes an accessible audio version. Researchers at Carnegie Mellon University believe that this CAPTCHA is not readable by current OCR technology.

Requires MediaWiki 1.8 or above.

Usage
See http://recaptcha.net/plugins/mediawiki/ for instructions.

Configuration
The following set rules strikes the right balance between keeping spam down and allowing unrestrictive access to users:
 * 1) Any user can edit the wiki, because registration puts people off.
 * 2) Unregistered users are always presented with a captcha.
 * 3) Registration requires a captcha.
 * 4) Registered users are never presented with a captcha.

In the MediaWiki config those rules looks like this:

// Fix the default captcha behaviour $wgGroupPermissions['*'           ]['skipcaptcha'] = false; $wgGroupPermissions['user'        ]['skipcaptcha'] = true; $wgGroupPermissions['autoconfirmed']['skipcaptcha'] = true; $wgGroupPermissions['bot'         ]['skipcaptcha'] = true; // registered bots $wgGroupPermissions['sysop'       ]['skipcaptcha'] = true;

$wgCaptchaTriggers['edit']         = true; $wgCaptchaTriggers['create']       = true; $wgCaptchaTriggers['createaccount'] = true;

(all other permissions having their default values)