Manual:$wgPingback/en

Implementation
The time and data sent is logged to the debug log when it is enabled. The data points are implemented in the  file.

Enabling the Pingback; Data collection and use
The web installer asks the user if they want to enable the feature during the installation of MediaWiki.

The user may choose at this time to opt out of the pingback. If the user opts in, the pingback feature will send new data on the first page load after upgrading to a new version of MediaWiki. Users may choose to enable or disable the pingback at any time by setting the $wgPingback configuration variable in LocalSettings.php. However, this will not delete any data that has already been transmitted to our servers.

The pingback anonymously tracks which version of MediaWiki is being used, along with the configured database type and PHP version, as well as your operating system, system type (32-bit or 64-bit), machine hardware, server software, and memory limit. The feature also sends a unique ID with the data transmission, which is used to track upgrades made to wikis over time.

You may view your wiki’s ID after a pingback is sent by running the following SQL command:

For more information, please see the complete MediaWiki Pingback privacy statement.

Access to data
Aggregate pingback data is available at https://pingback.wmflabs.org.

Currently the raw pingback data is stored in Wikimedia's EventLogging database. Users with a signed NDA with the WMF (see Volunteer NDA for the process) can access the data via analytics machines.