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Extension:ConfirmEdit

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This extension comes with MediaWiki 1.18 and above. Thus you do not have to download it again. However, you still need to follow the other instructions provided.
MediaWiki extensions manual
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ConfirmEdit
Release status: stable
MediaWiki Extension ConfirmEdit.png
Implementation Page action
Description Adds CAPTCHAs for page saves and other user actions
Author(s)
  • Brion Vibber
  • Florian Schmidt
  • Sam Reed
Latest version 1.6.0 (Continuous updates)
MediaWiki 1.31+
PHP 5.5.9+
Database changes No
License GNU General Public License 2.0 or later
Download
  • $wgCaptchaWhitelistIP
  • $wgCaptcha
  • $wgCaptchaClass
  • $wgCaptchaTriggers
  • $wgCaptchaTriggersOnNamespace
  • $wgCaptchaStorageClass
  • $wgCaptchaSessionExpiration
  • $wgCaptchaBadLoginExpiration
  • $wgCaptchaBadLoginPerUserExpiration
  • $ceAllowConfirmedEmail
  • $wgCaptchaBadLoginAttempts
  • $wgCaptchaBadLoginPerUserAttempts
  • $wgCaptchaWhitelist
  • $wgCaptchaRegexes
skipcaptcha
Translate the ConfirmEdit extension if it is available at translatewiki.net
Check usage and version matrix.
Vagrant role confirmedit
Issues Open tasks · Report a bug

The ConfirmEdit extension lets you use various different CAPTCHA techniques, to try to prevent spambots and other automated tools from editing your wiki, as well as to foil automated login attempts that try to guess passwords.

ConfirmEdit ships with several techniques/modules to generate captcha.

Module Description Effectiveness at stopping spam
SimpleCaptcha Users have to solve a simple math problem. Low
FancyCaptcha Users have to identify a series of characters, displayed in a stylized way. Low
MathCaptcha Users have to solve a math problem that's displayed as an image. Low
QuestyCaptcha Users have to answer a question, out of a series of questions defined by the administrator(s). Very high, until cracked
ReCaptcha NoCaptcha Users are presented with a JavaScript-based check of humanity. If the check is failed, a puzzle is presented. Medium to low

Some of these modules require additional setup work:

  • MathCaptcha requires both the presence of TeX and, for versions of MediaWiki after 1.17, the Math extension;
  • FancyCaptcha requires running a preliminary setup script in Python.

Caveats: CAPTCHAs reduce accessibility and cause inconvenience to human users. In addition, they are not 100% effective against bots, and they will not protect your wiki from spammers who are willing and able to use human labor to get through the CAPTCHAs. You may wish to use ConfirmEdit in conjunction with other anti-spam features. Regardless of the solution you use, if you have a publicly-editable wiki it's important to keep monitoring the "Recent changes" page.

InstallationEdit

ConfirmEdit may not work if used with a MediaWiki version different from the one specified when downloading via the "Extension distributor".
  • If using Vagrant , install with vagrant roles enable confirmedit --provision
Manual installation
  • Download and place the file(s) in a directory called ConfirmEdit in your extensions/ folder.

CAPTCHA typesEdit

There are numerous different CAPTCHA types included with ConfirmEdit.

QuestyCaptchaEdit

This module presents a question and the user supplies the answer. You provide the questions in the configuration. This module has proven to offer a strong mechanism against spam bots; it also should have the advantage of a better accessibility, as textual questions can be read by text-to-speech software allowing visually impaired users (but not bots) to answer correctly.

Add the following to LocalSettings.php to enable this CAPTCHA, editing the Q&A:

// If your MediaWiki version is 1.25 or higher, use this line:
wfLoadExtensions([ 'ConfirmEdit', 'ConfirmEdit/QuestyCaptcha' ]);

// Else use these lines:
require_once "$IP/extensions/ConfirmEdit/ConfirmEdit.php";
require_once "$IP/extensions/ConfirmEdit/QuestyCaptcha.php";

// Add your questions in LocalSettings.php using this format:
$wgCaptchaQuestions = [
	'What is the capital of France?' => 'Paris',
	'What is the capital of Spain' => 'MADRID', // Answers are case insensitive
	'What is the name of this wiki?' => $wgSitename, // You can use variables
	'How many fingers does a hand have?' => [ 5, 'five' ], // A question may have many answers
];

You can also configure ConfirmEdit's triggers and other options, If the Captcha does not appear add the following behind the code. This means that the captcha is triggered that means called if you do the named actions like edit a page or create a page. You can write "true" to make it happen and "false" to make it not happen.

$wgMainCacheType    = CACHE_ANYTHING;
$wgCaptchaTriggers['edit']          = true;
$wgCaptchaTriggers['create']        = true;
$wgCaptchaTriggers['createtalk']    = true;
$wgCaptchaTriggers['addurl']        = true;
$wgCaptchaTriggers['createaccount'] = true;
$wgCaptchaTriggers['badlogin']      = true;

It will randomly choose a question from those supplied. The minimum is one.

  • QuestyCaptcha is case-insensitive. If the answer is "Paris" and the user writes "paris", or if the answer is "paris" and the user writes "Paris", it will still work.
  • If the answer has a special character like "ó", you may write an answer with "ó" and another without, just in case. For example if the answer is "canción" you can use [ 'cancion', 'canción' ] in case the user is lazy (or ignorant) and writes "cancion".
  • The answer must be easy to guess for a human interested in your wiki, but not by an automatic program. Ideally, it should not be contained in the text of the question; you can try and edit the captcha help messages[1] and provide the solution to the captcha response there.
  • Just change the questions when/if they start proving ineffective; this may never happen if your wiki is not specifically targeted.
  • Don't ever reuse questions already used by you or others in the past: spambots are known to remember a question and its answer forever once they broke it.
  • You can even dynamically generate questy captchas in the configuration. DO NOT use an exact copy of the dynamic questions from the link -- they've been cracked by spammers. However other dynamic questions in the style of the questions presented are highly effective.

ReCaptcha (NoCaptcha)Edit

The ReCaptchaNoCaptcha module was introduced in the MediaWiki release 1.26; you can't use it in older versions of ConfirmEdit and MediaWiki.

The new generation of ReCaptcha, called NoCaptcha, was introduced by Google back in December 2014[2] and reduces the need for humans to solve a CAPTCHA. Based on a user-side JavaScript (which can't be controlled by the user the administrator), reCaptcha tries to identify the site user as a human by analyzing their browsing behavior on the page. The user then has to click an "I'm not a robot" checkbox and (in the best case) doesn't have to do anything further to prove they're a human. However, in some cases, the user still has to solve a CAPTCHA image.

Note: ReCaptcha will not work with the VisualEditor.

This module implements the new ReCaptcha NoCaptcha solution in ConfirmEdit. You still need a public and a secret key (which you can retrieve from the ReCaptcha admin panel – change v2, v3 not work) and install the plugin with:

wfLoadExtensions([ 'ConfirmEdit', 'ConfirmEdit/ReCaptchaNoCaptcha' ]);
$wgCaptchaClass = 'ReCaptchaNoCaptcha';
$wgReCaptchaSiteKey = 'your public/site key here';
$wgReCaptchaSecretKey = 'your private key here';

There is an additional configuration option for this module, $wgReCaptchaSendRemoteIP (default: false), which, if set to true, sends the IP address of the current user to a server from Google while verifying the CAPTCHA. You can improve the privacy for your users if you keep this set to "false". However, remember, that this module adds a client side JavaScript code, directly loaded from a server from Google, which already can collect the IP address of the user (combined with other data, too) and can not be limited by a configuration option. This will only work on standard MediaWiki editor.

SimpleCaptcha (calculation)Edit

  Warning: This type is used by very few wikis outside WMF if any, probably because of scarce effectiveness.
 
a simple math question.

This is the default CAPTCHA. This module provides a simple addition or subtraction question for the user.

Add the following lines to LocalSettings.php in the root of your MediaWiki to enable this CAPTCHA:

$wgCaptchaClass = 'SimpleCaptcha';

Note that the display of a trivial maths problem as plaintext yields a captcha which can be trivially solved by automated means; as of 2012, sites using SimpleCaptcha are receiving significant amounts of spam and many automated registrations of spurious new accounts. VisualMathCaptcha is also relatively easily defeated. Wikis currently using this as the default should therefore migrate to one of the other CAPTCHAs.

FancyCaptchaEdit

  Warning: This type is used by very few wikis outside WMF if any, probably because of scarce effectiveness.

This module displays a stylized image of a set of characters. The Python Imaging Library must be installed in order to create the set of images initially, but isn't needed after that (can be installed with pip install pil in most environments).

  1. Add the following lines to LocalSettings.php in the root of your MediaWiki installation:
    MediaWiki version is 1.25 or newer:
    wfLoadExtensions([ 'ConfirmEdit', 'ConfirmEdit/FancyCaptcha' ]);
    $wgCaptchaClass = 'FancyCaptcha';
    MediaWiki version is older than 1.25:
    require_once "$IP/extensions/ConfirmEdit/ConfirmEdit.php";
    require_once "$IP/extensions/ConfirmEdit/FancyCaptcha.php";
    $wgCaptchaClass = 'FancyCaptcha';
  2. In LocalSettings.php, set the variable $wgCaptchaDirectory to the directory where you will store Captcha images. Below it set $wgCaptchaSecret to your passphrase.
  3. Create the images by running the following, where:
    • font is a path to some font, for instance AriBlk.TTF.
    • wordlist is a path to some word list, for instance /usr/share/dict/words. (Note: on Debian/Ubuntu, the 'wbritish' and 'wamerican' packages provide such lists. On Fedora, use the 'words' package).
    • key is the the exact passphrase you set $wgCaptchaSecret to. Use quotes if necessary.
    • output is the path to where the images should be stored (defined in $wgCaptchaDirectory).
    • count is how many images to generate.
    python /path/to/captcha.py --font=<font> --wordlist=<wordlist> --key=<key> --output=<output> --count=<count>
    • An example, assuming you're in the extensions/ConfirmEdit directory (font location from Ubuntu 6.06, probably different on other operating systems):
    python captcha.py --font=/usr/share/fonts/truetype/freefont/FreeSans.ttf --wordlist=/usr/share/dict/words --key=FOO --output=../../../captcha --count=100
    • If you are not satisfied with the results of the words you've generated you can simply remove the images and create a new set. Comic_Sans_MS_Bold.ttf seems to generate relatively legible words, and you could also edit the last line of captcha.py to increase the font size from the default of 40.
  4. Put the images you get into captcha directory in your installation
  5. Edit your wiki's LocalSettings.php : specify full path to your captcha directory in $wgCaptchaDirectory and secret key you've been using while generating captures in $wgCaptchaSecret
$wgCaptchaDirectory = "/.php-data/my-wiki.org/wiki/captcha";
$wgCaptchaDirectoryLevels = 0; // Set this to a value greater than zero to break the images into subdirectories
$wgCaptchaSecret = "FOO"; // same value you used in --key option in captcha.py

See also wikitech:Generating CAPTCHAs for how Wikimedia Foundation does it.

How to avoid common problems running Python
  1. Install the most recent version of Python Imaging Library (PIL).
  2. Make the installation of Python on a short folder name. Like C:\Python\
  3. Create a folder like C:\Ex and place files CAPTCHA.py / FONT.ttf / LIST.txt into the folder.
  4. To execute easily, run the following example as a batch file:
C:\python\python.exe C:\Ex\CAPTCHA.py --font C:\Ex\FONT.ttf --wordlist C:\Ex\LIST.txt --key=YOURPASSWORD --output C:\Ex\ --count=20

MathCaptchaEdit

  Warning: This type is used by very few wikis outside WMF if any, probably because of scarce effectiveness.
This requires the Math extension to be installed. See also Extension:Math

This module generates an image using TeX to ask a basic math question.

Set the following to enable this CAPTCHA:

// Use this line ONLY if your MediaWiki version is 1.25 or newer:
wfLoadExtension( 'ConfirmEdit/MathCaptcha' );
// Use this line ONLY if your MediaWiki version is older than 1.25:
require_once "$IP/extensions/ConfirmEdit/MathCaptcha.php";
$wgCaptchaClass = 'MathCaptcha';

See the readme file in the math folder to install this captcha.

ConfigurationEdit

ConfirmEdit introduces a 'skipcaptcha' permission type to wgGroupPermissions . This lets you set certain groups to never see CAPTCHAs. All of the following can be added to localsettings.php.

Defaults from ConfirmEdit.php:

$wgGroupPermissions['*'            ]['skipcaptcha'] = false;
$wgGroupPermissions['user'         ]['skipcaptcha'] = false;
$wgGroupPermissions['autoconfirmed']['skipcaptcha'] = false;
$wgGroupPermissions['bot'          ]['skipcaptcha'] = true; // registered bots
$wgGroupPermissions['sysop'        ]['skipcaptcha'] = true;

To skip captchas for users that confirmed their email, you need to set both:

$wgGroupPermissions['emailconfirmed']['skipcaptcha'] = true;
$ceAllowConfirmedEmail = true;

There are five "triggers" on which CAPTCHAs can be displayed:

  • 'edit' - triggered on every attempted page save
  • 'create' - triggered on page creation
  • 'addurl' - triggered on a page save that would add one or more URLs to the page
  • 'createaccount' - triggered on creation of a new account
  • 'badlogin' - triggered on the next login attempt after a failed one. Requires $wgMainCacheType to be set to something other than CACHE_NONE in your LocalSettings.php, if in doubt the following will always work. Note that badlogin does not trigger captchas on API login, but instead blocks them outright until $wgCaptchaBadLoginExpiration expires.
$wgMainCacheType = CACHE_ANYTHING;

The default values for these are:

$wgCaptchaTriggers['edit'] = false; 
$wgCaptchaTriggers['create'] = false; 
$wgCaptchaTriggers['addurl'] = true; 
$wgCaptchaTriggers['createaccount'] = true;
$wgCaptchaTriggers['badlogin'] = true;

The triggers edit, create and addurl can be configured per namespace using the $wgCaptchaTriggersOnNamespace setting. If there is no $wgCaptchaTriggersOnNamespace for the current namespace, the normal $wgCaptchaTriggers apply. So suppose that in addition to the above $wgCaptchaTriggers defaults we configure the following:

$wgCaptchaTriggersOnNamespace[NS_TALK]['addurl'] = false;
$wgCaptchaTriggersOnNamespace[NS_PROJECT]['edit'] = true;

Then the CAPTCHA will not trigger when adding URLs to a talk page, but on the other hand user will need to solve a CAPTCHA any time they try to edit a page in the project namespace, even if they aren't adding a link.

URL and IP whitelistsEdit

It is possible to define a whitelist of known "good" sites for which the CAPTCHA should not kick in, when the 'addurl' action is triggered.

Sysop users can do this by editing the system message page called [[MediaWiki:Captcha-addurl-whitelist]]. The expected format is a set of regex's one per line. Comments can be added with # prefix. You can see an example of this usage on OpenStreetMap.

This set of whitelist regexes can also be defined using the $wgCaptchaWhitelist config variable in LocalSettings.php, to keep the value(s) a secret.

Some other variables you can add to LocalSettings.php:

  • $wgCaptchaWhitelistIP - List of IP ranges to allow to skip the CAPTCHA (you can also use [[MediaWiki:Captcha-ip-whitelist]]; see below for details).
  • $ceAllowConfirmedEmail - Allow users who have confirmed their e-mail addresses to post URL links

These are described more thoroughly in the code comments

[[MediaWiki:Captcha-ip-whitelist]] can be used to change the whitelisted IP addresses and IP ranges on wiki. They should be separated by newlines. If any other character (apart from a valid IP address or range) is found on a line, it will be ignored but leading and trailing whitespace characters are allowed. For example, a line with only 127.0.0.1 is considered valid but #127.0.0.1 will be ignored.

Regular expressionsEdit

The global variable wgCaptchaRegexes accepts an array of regexes to be tested against the page text and will trigger the CAPTCHA in case of a match.

Wikimedia approachEdit

For example, Wikimedia Foundation wikis use FancyCaptcha with a custom set of images and the default configuration, modified by what follows.

$wgGroupPermissions['autoconfirmed']['skipcaptcha'] = true;

This means only unregistered and newly registered users have to pass the CAPTCHA.

EmergencyCaptcha modeEdit

Additionally the shortcut named $wmgEmergencyCaptcha is designed for use in a limited number of emergency situations, for instance in case of massive vandalism or spam attacks: it changes the default trigger values (see above) into the following:

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

So all anonymous and new users have to solve a CAPTCHA also before being able to save an edit or create a new page, in addition to the normal situation.

Rate-LimitingEdit

With Gerrit change 182551, ConfirmEdit supports rate limiting for false CAPTCHA. For more information about $wgRateLimits and how to set it up, read Manual: $wgRateLimits , the action key is badcaptcha.

AuthorsEdit

The basic framework was designed largely by Brion Vibber, who also wrote the SimpleCaptcha and FancyCaptcha modules. The MathCaptcha module was written by Rob Church. The QuestyCaptcha module was written by Benjamin Lees. Additional maintenance work was done by Yaron Koren.

ReferencesEdit

  1. MediaWiki:Questycaptchahelp-text, MediaWiki:Questycaptcha-edit, MediaWiki:Questycaptcha-addurl, MediaWiki:Questycaptcha-create and MediaWiki:Questycaptcha-createaccount.
  2. Google Blog Are you a robot? Introducing “No CAPTCHA reCAPTCHA” (December 3, 2014)

See alsoEdit