Manual:$wgPingback

System information reported
Other reported data is in the 1>#Privacy of Data|Privacy of Data section.

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

Overall Privacy Considerations
Beware! The current edit of this page should not be considered an authoritative source about how the pingback feature works in MediaWiki.

For 4 months after the implementation of the pingback feature into the master branch, and over 1 month after it's wide release, this page maintained a incomplete list of system data points and falsely claimed the feature only sent anonymous data.

MediaWiki has had a consistent track record over the years of changes being made to the software without updating the MediaWiki manual to reflect those changes.

MediaWiki's wmf>wmf:Privacy policy|privacy policy appears to cover data collected via the pingback feature.

In discussion of this feature, there have been requests for more data points and there is no specific policy on how new proposed data points will be evaluated.

MediaWiki installer and documentation asks users to subscribe to the MediaWiki announce mailing list, but changes to it's privacy policy which affect this feature are likely to be published only to WikimediaAnnounce-L, since this data is a small fraction of the overall data that Wikimedia collects, and it's privacy policy states changes will be published "via a notification on WikimediaAnnounce-L or a similar mailing list."

Privacy of Data
Installations are identified by a string that is generated when the pingback feature is first used and remains the same unless manually removed (it is stored in the  table under the   key).

While the string is completely random, this string does uniquely identify a MediaWiki installation. It can be used to relate requests to one certain installation.

In the EventLogging data it is stored in the   column.

The public ip of the machine is reported to Wikimedia because the method of transmission is an http post request to https://www.mediawiki.org.

This data is not part of the EventLogging database schema, but it is within Wikimedia's privacy policy to store this information and it is typical to use it for system administration of the collection server and for screening out invalid data.

MediaWiki sends the data shortly after the first page load when the setting is enabled.

This can be used to infer personal information about the MediaWiki user as different populations are highly correlated with use of computers at different times and dates.

The documentation says the data is sent "periodically" and "from time to time", but in computer terms that implies an extremely wide range.

It would be useful for someone to figure out and document just how often that is because if it is frequent enough, it would constitute uptime data.

Access to data
Currently the data is stored in Wikimedia's EventLogging database.

Users with a signed NDA with the WMF can access the data via analytics machines.

It is planned to make aggregated data publicly available (see T152222).