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Issue tracker: #CheckUser
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CheckUser
Release status: stable
Implementation Special page , User identity , API , Hook , Database
Description CheckUser function allows a user with permissions to check which IPs are used by a given username and which usernames are used by a given IP, without having to run queries directly against the database by hand.
Author(s) Tim Starling, Aaron Schulz, Dreamy Jazz
Latest version 2.5 (continuous updates)
Compatibility policy Snapshots releases along with MediaWiki. Master is not backward compatible.
MediaWiki 1.39+
PHP 7.4.3+
Database changes Yes
Virtual domain virtual-checkuser-global
Tables cu_changes
cu_log_event
cu_private_event
cu_log
cu_useragent_clienthints
cu_useragent_clienthints_map
cu_useragent
cuci_wiki_map
cuci_temp_edit
cuci_user
License GNU General Public License 2.0 or later
Download
Download extension
Git [?]:
Parameters
  • $wgCheckUserGBtoollink
  • $wgCheckUserClientHintsSpecialPages
  • $wgCheckUserCAMultiLock
  • $wgCheckUserLogSuccessfulBotLogins
  • $wgCheckUserSpecialPagesWithoutIPRevealButtons
  • $wgCheckUserLogLogins
  • $wgCUPublicKey
  • $wgCheckUserCAtoollink
  • $wgCheckUserCuciUserRandomChanceDebounceCutoff
  • $wgCheckUserClientHintsRestApiMaxTimeLag
  • $wgCheckUserDeveloperMode
  • $wgCheckUserWriteToCentralIndex
  • $wgCheckUserCentralIndexRangesToExclude
  • $wgCUDMaxAge
  • $wgCheckUserCIDRLimit
  • $wgCheckUserMaxBlocks
  • $wgCheckUserCentralIndexGroupsToExclude
  • $wgCheckUserDisplayClientHints
  • $wgCheckUserGlobalContributionsCentralWikiId
  • $wgCheckUserForceSummary
  • $wgCheckUserInvestigateMaximumRowCount
  • $wgCheckUserMaximumIPsToAutoblock
  • $wgCheckUserClientHintsForDisplay
  • $wgCheckUserClientHintsValuesToHide
  • $wgCheckUserClientHintsUnsetHeaderWhenPossible
  • $wgCheckUserCollapseCheckUserHelperByDefault
  • $wgCheckUserClientHintsEnabled
  • $wgCheckUserTemporaryAccountMaxAge
  • $wgCheckUserMaximumRowCount
  • $wgCheckUserClientHintsHeaders
Added rights

  • checkuser
  • checkuser-log
  • checkuser-temporary-account
  • investigate
Hooks used
Hooks provided
Quarterly downloads 200 (Ranked 28th)
Public wikis using 9,118 (Ranked 13th)
Translate the CheckUser extension if it is available at translatewiki.net
Issues Open tasks · Report a bug
This page is about the extension itself. For the Wikimedia Foundation CheckUser policy, see m:CheckUser policy.

CheckUser is an extension that allows a user (with the checkuser permission) to check which IP addresses are used by a given username and which usernames are used by a given IP, without having to run queries directly against the database by hand. The extension is running live on all Wikimedia wikis.

Updates will be made according to the needs of Wikimedia Foundation wikis; or where critical vulnerabilities are discovered.

Installation

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  • Download and move the extracted CheckUser folder to your extensions/ directory.
    Developers and code contributors should install the extension from Git instead, using:cd extensions/
    git clone https://gerrit.wikimedia.org/r/mediawiki/extensions/CheckUser
  • Only when installing from Git, run Composer to install PHP dependencies, by issuing composer install --no-dev in the extension directory. (See task T173141 for potential complications.)
  • Add the following code at the bottom of your LocalSettings.php file: 
    wfLoadExtension( 'CheckUser' );
  • Run the update script which will automatically create the necessary database tables that this extension needs.
  • Configure as required.
  • Yes Done – Navigate to Special:Version on your wiki to verify that the extension is successfully installed.

Using MediaWiki-Docker

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Follow the steps in MediaWiki-Docker/Extension/CheckUser to install this extension inside a MediaWiki Docker instance.

Configuration

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This tool copies recent changes data to separate tables, and adds to that when new entries are added. If $wgPutIPinRC is set to false, the copied data will not contain the associated IP address. However, entries added after installation of this extension will contain the IP address.

After installation of this extension, you can reduce $wgRCMaxAge to make recentchanges shorter without affecting checkuser. Use $wgCUDMaxAge to set how far back checkuser data can go, in seconds.

The CheckUser-specific setting $wgCheckUserCIDRLimit determines the largest range that can be checked in a single check. Its format is the same as $wgBlockCIDRLimit . The default limit is /32 for IPv6 checks and /16 for IPv4 checks.

To allow this tool to log successful and failed login attempts as well as logouts, set $wgCheckUserLogLogins to true. If you have bot accounts on your wiki, setting $wgCheckUserLogSuccessfulBotLogins to false will skip logging successful login attempts to bot accounts.

MediaWiki version:
≥ 1.43

If the extension is installed on a multi-wiki install, then you should set $wgVirtualDomainsMapping for the virtual-checkuser-global to point to a central database table. Setting this will ensure that the central index tables are actually on a central DB, and therefore the GlobalBlocking global autoblocks and GUC work. After doing this, you will need to run update.php to create the tables on the central wiki.

Granting right to use CheckUser

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To grant the right to use Special:CheckUser, Special:Investigate and Special:CheckUserLog, a user with user rights management must go to Special:UserRights and enter the user's name in the box, then select the option "checkuser". Once this is done, the aforementioned special pages will show up in Special:SpecialPages page for that user.

To allow users to access the IP addresses of temporary accounts , they should be granted the checkuser-temporary-account right.

To give sysops all the rights this extension provides, put the following into LocalSettings.php: 

$wgGroupPermissions['sysop']['checkuser'] = true;
$wgGroupPermissions['sysop']['checkuser-log'] = true;
$wgGroupPermissions['sysop']['investigate'] = true;
$wgGroupPermissions['sysop']['checkuser-temporary-account'] = true;

To only allow the adding and removing of the checkuser permission, use the following instead: 

$wgAddGroups['sysop'][] = 'checkuser';
$wgRemoveGroups['sysop'][] = 'checkuser';

Configuration

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Configuration settings in extension.json
parameter default comment
$wgCUDMaxAge 7776000 How long to keep CU data (in seconds)? (default = 90 days)
$wgCheckUserMaxBlocks 200 Mass block limits
$wgCheckUserForceSummary false Set this to true if you want to force checkusers into giving a reason for each check they do through Special:CheckUser. (Not very useful, given that checkusers could simply give a summary such as "they need to be checked" or "I feel like it" and the software would not know.)
$wgCheckUserCIDRLimit [ 'IPv4' => 16, 'IPv6' => 19 ] Smallest CIDR value that can be used in any individual range check
$wgCUPublicKey '' Public key to encrypt private data that may need to be read later. Generate a public key with something like:

openssl genrsa -out cu.key 2048; openssl rsa -in cu.key -pubout > cu.pub and paste the contents of cu.pub here

Used with an associated private key to encrypt certain data that is not shown to CUs but stored in the cu_changes or cu_private_event table. Currently this is only the recipients of emails. Without a valid public key the data will not be stored.

$wgCheckUserCAMultiLock false This can be used to add a link to Special:MultiLock by CentralAuth to the Special:CheckUser's mass block form. This requires the CentralAuth extension to be installed on the wiki. To enable this, set this to an array with a central wiki's database name and an array with the name(s) of the global group(s) to add the link for. For example: 
$wgCheckUserCAMultiLock = [
    'centralDB' => 'metawiki',
    'groups' => [ 'steward' ]
];
$wgCheckUserCAtoollink false Since 77360f1cf1d2. This adds a link to central wiki Special:CentralAuth to the Special:CheckUser's "Get users" results. This requires the CentralAuth extension to be installed on the wiki. To enable this, set this with a central wiki's database name. For example: 
$wgCheckUserCAtoollink = 'metawiki';
$wgCheckUserGBtoollink false Since 77360f1cf1d2. This adds a link to local or central wiki Special:GlobalBlock to the Special:CheckUser's "Get users" results. This requires the GlobalBlocking extension to be installed on the wiki. To enable this, if a $wgConf is configured, set this to an array with a central wiki's database name and an array with the name(s) of the local (or global if you have CentralAuth installed) group(s) to add the link for. For example: 
$wgCheckUserGBtoollink = [
	'centralDB' => 'metawiki',
	'groups' => [ 'steward', 'staff' ]
];
$wgCheckUserEnableSpecialInvestigate (1.35-1.43) false (<=1.39)
true (1.40+) 		Since 57dcfe46d2e4. This enables Special:Investigate, an updated version of Special:CheckUser that allows checking for multiple user accounts and IP addresses within one investigation.
$wgCheckUserLogLogins false Whether CheckUser should log login and logout attempts (both successful and not).
$wgCheckUserLogSuccessfulBotLogins true Whether CheckUser should store successful login attempts to accounts with the bot user group if $wgCheckUserLogLogins is set to true. Only is used if $wgCheckUserLogLogins is true
$wgCheckUserMaximumRowCount 5000 The maximum number of results that can be returned by Special:CheckUser. Before MediaWiki 1.39, in the 'Get edits' and 'Get IPs' results having over 5,000 results would return the results in a different format. From MediaWiki 1.39 this is the maximum number of results to show by page and more can be generated using the paging links
$wgCheckUserInvestigateMaximumRowCount 25000 Similar to $wgCheckUserMaximumRowCount, but for Investigate
$wgCheckUserTemporaryAccountMaxAge (1.40+) 86400 The number of seconds for which the temporary account API response is fresh.
$wgCheckUserEventTablesMigrationStage (1.40+) 3 (1.40)
259 (1.41)
769 (1.42-1.43)
768 (1.43) 		Used to control the migration stage of log events stored in cu_changes to the new cu_log_event and cu_private_event tables. Is temporary and will be removed once migration is complete.
$wgCheckUserClientHintsEnabled (1.41+) true Used to control whether client hints should be collected and displayed in results by CheckUser.
$wgCheckUserClientHintsSpecialPages (1.41+) [ "CreateAccount", "Emailuser", "PasswordReset", "Userlogin", "Userlogout" ] The list of SpecialPages where CheckUser will request client hints if $wgCheckUserClientHintsEnabled is true.
$wgCheckUserClientHintsActionQueryParameter (1.41+) [ "history" ] The list of "action" values in the query parameters where client hints will be requested.
$wgCheckUserClientHintsHeaders (1.41+) { "Sec-CH-UA": "", "Sec-CH-UA-Arch": "architecture", "Sec-CH-UA-Bitness": "bitness", "": "brands", "Sec-CH-UA-Form-Factor": "", "Sec-CH-UA-Full-Version-List": "fullVersionList", "Sec-CH-UA-Mobile": "mobile", "Sec-CH-UA-Model": "model", "Sec-CH-UA-Platform": "platform", "Sec-CH-UA-Platform-Version": "platformVersion", "Sec-CH-UA-WoW64": ""} The list of client hint types that will be requested. Keys represent the client hint values requested using the Accept-CH header. Values represent the equivalent name when requesting them from the JS client side client hints API.
$wgCheckUserClientHintsUnsetHeaderWhenPossible (1.41+) true If true, the server will send an empty Accept-CH header when the user is viewing a page which does not need client hints data.


Special:CheckUser usage

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Basic interface

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  1. Go to Special:CheckUser.
  2. In the user field, type in the username (without the User: prefix), IP address, or CIDR range.
    • IP: any IPv4 or IPv6 address.
    • CIDR: you can check a range of IP addresses by appending the CIDR prefix. The CIDR prefix value for IPv4 can be between 16-32 and the value for IPv6 can be between 19-128. The smaller number for both ranges can be changed using the configuration variable $wgCheckUserCIDRLimit. For notation, see Help:Range blocks .
    • XFF: you can check a client IP address provided by X-Forwarded-For headers by appending /xff (for example, 127.0.0.1/xff).
  3. Select the information you want to retrieve.
    • Get IP addresses - returns IP addresses used by a registered user.
    • Get actions - returns all edits and logged actions made by users using an IP address or range specified in the target field, or if the target is a user all edits and logged actions by that user.
    • Get users - returns user accounts that have edited from an IP or range.
  4. In the "Reason:" field, type in the reason you are accessing the confidential data. Try to succinctly summarise the situation (for example, "cross-wiki spam"); this will be logged in a log visible only to users with the checkuser-log permission.
  • Screenshots
  • Basic CheckUser interface
    Basic CheckUser interface
  • Example username check
    Example username check
  • Example IP check
    Example IP check
  • Example Get edits check
    Example Get edits check
  • Example log
    Example log

Information returned

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A typical entry in the CheckUser results for a user summary ("get users") is as follows:


  1. Example user agent

This is formatted to fit a lot of information into a format that can very easily be listed and skimmed, but is difficult to read unless you know what the information provided is. The information is laid out as follows:

  • username (user links) (time period when they edited from the given IP or range) [number of edits from the IP or range]
    1. IP address edited from XFF: XFF information provided (can be spoofed)

Each IP/XFF combination used to edit is listed, in order of use.

The last ten user agents (browser, operating system, system language, and versions) for each user for edits made in the IP or range are listed afterwards.

XFF Format

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XFF (X-Forwarded-For) headers indicate the series of IP addresses used from the user's computer (first) to the last proxy server. In case of Wikimedia, the last proxy server is one of the Wikimedia proxies (listed under $wgCdnServersNoPurge in the Wikimedia configuration file).

In this example:

aaa.aaa.aaa.aaa XFF: 10.4.46.42, 127.0.0.1, aaa.aaa.aaa.aaa, 208.80.152.46

  • the first two addresses (10.4.46.42, 127.0.0.1) are private to the originating network and can't be reached directly from the public Internet,
  • the third address (aaa.aaa.aaa.aaa) is the "public face" of the editor, usually a broadband or dial-up ISP, a company gateway, (but possibly an anonymizer or a malware-compromised server),
  • the last address (208.80.152.46) is one of the Wikimedia squids (sq36.wikimedia.org).

MediaWiki configuration settings $wgUsePrivateIPs , $wgCdnServers , $wgCdnServersNoPurge and extensions using the IsTrustedProxy hook (such as Extension:TrustedXFF ) change the way an actual IP address used to attribute edits is selected.

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When you get results from Special:CheckUser you can add personal user tool links via the following interface messages:

  • MediaWiki:checkuser-userlinks-ip for IP addresses (for example m:MediaWiki:checkuser-userlinks-ip)
  • MediaWiki:Checkuser-userlinks for registered users (for example m:MediaWiki:Checkuser-userlinks)
  • MediaWiki:checkuser-toollinks for IPs in the 'Get IP Addresses' check type (for example m:MediaWiki:checkuser-toollinks)
  • MediaWiki:Checkuser-cidr-tool-links for IP ranges produced by the CIDR calculator present at the bottom of all Special:CheckUser pages. Interface message added in 1.41.

Special:Investigate usage

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Basic usage

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  1. Go to Special:Investigate.
  2. In the Usernames and IP addresses field, type in up to 10 targets, which may be usernames (without the User: prefix), IP addresses, or CIDR ranges.
  3. In the Reason field, enter the reason you are accessing the confidential data, as described in the Special:CheckUser instructions above; this will be logged in a log visible only to users with the checkuser-log permission.
  • Screenshots
  • Input form
    Input form
  • Account information tab
    Account information tab
  • IPs and user agents tab
    IPs and user agents tab
  • Timeline tab
    Timeline tab

For advanced feature usage, see Help:Special Investigate.

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As with Special:CheckUser, links to external tools can be customized.

The links are defined in the checkuser-investigate-compare-toollinks message. This message is parsed to find links, which are added to the menu in the IPs & User agents tab.

Showing IPs for temporary accounts

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MediaWiki version:
≥ 1.40

The CheckUser extension will show since MediaWiki 1.40 a button that is displayed next to temporary account user links which allows the revealing of their IP address.

This functionality is available exclusively to users with the checkuser-temporary-account privilege, granting them the ability to view the IP addresses that are linked to temporary accounts. To access this information, the Enable revealing IP addresses for temporary accounts feature must be enabled on the user's Special:Preferences page.

These buttons will appear wherever user links are shown for a temporary account, such as when viewing page histories or in Special:Contributions. However, these will not be shown on Special:CheckUser, Special:Investigate or Special:InvestigateBlock.

APIs

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CheckUser and CheckUserLog API

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CheckUser provides an API that allows access to the information shown on Special:CheckUser and Special:CheckUserLog. These two APIs work fairly similarly to the special pages, but the reason for a check using the checkuser API is prefixed with "API:" to indicate they were made using the API. Example usages of these APIs are shown below.

CheckUser API
api.php?action=query&list=checkuser&curequest=userips&cutarget=Jimbo_Wales
api.php?action=query&list=checkuser&curequest=edits&cutarget=127.0.0.1/16&xff=1&cureason=Some_check
CheckUserLog API
api.php?action=query&list=checkuserlog&culuser=WikiSysop&cullimit=25
api.php?action=query&list=checkuserlog&cultarget=127.0.0.1&culfrom=20111015230000

Temporary Account Reveal API

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MediaWiki version:
≥ 1.40

Usage

The TemporaryAccountHandler class offers API endpoints for retrieving the IP addresses associated with temporary user accounts. To access this information, the Enable revealing IP addresses for temporary accounts feature must be enabled on the user's Special:Preferences page.

API endpoint

GET /rest.php/checkuser/v0/temporaryaccount/{name} where {name} is the user name you want to look up

Response

If the request is successful, the API will respond with a JSON object containing the following fields:

Name Type Description
ips string[] IPs of the given temporary account

If the request fails, the API will respond with an appropriate error code and message.

Example request

GET /rest.php/checkuser/v0/temporaryaccount/*Unregistered%202

Example response

{"ips": [ "114.127.69.62" , "212.47.235.82" , "212.47.235.81" ]}

TemporaryAccountRevisionHandler

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The TemporaryAccountRevisionHandler class offers API endpoints for viewing the IP associated with a revision for temporary accounts. You can specify one or multiple revision IDs in the query string.

API endpoint

GET /rest.php/checkuser/v0/temporaryaccount/*Unregistered%203/revisions/{revisionId} where {revisionId} is the revision ID(s) you want to look up separated by the | character.

Response

If the request is successful, the API will respond with a JSON object containing the following fields:

Name Type Description
ips dictionary The revision ID as the key and the associated IP address as the value.

If the request fails, the API will respond with an appropriate error code and message.

Example request

GET /rest.php/checkuser/v0/temporaryaccount/*Unregistered%203/revisions/31

Example response

{"ips":{"31":"40.175.36.227"}}

Example request with multiple revisions

GET /w/rest.php/checkuser/v0/temporaryaccount/*Unregistered%205/revisions/194|193

Example response

{"ips":{"194":"40.175.36.227","193":"1.2.3.4"}}

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