User:Rentier/ProxyBlock

As a result of the abuse, such as vandalism, spam and sockpuppetry, done from behind proxy servers, IP addresses belonging to web hosts and anonymizing proxies are normally blocked on sight in accordance with the blocking policy. However, the existing detection processes are ineffective. It is easy to find an unblocked proxy server. I ran a test using one of the popular VPN proxy providers and found that only about half of their IP addresses were blocked.
 * Results of a test using one of the popular VPN proxy providers

We already have TorBlock
The MediaWiki Extension:TorBlock is used to apply restrictions to users editing via the Tor anonymity network. It uses a periodically updated list of IP addresses belonging to Tor exit nodes. On English Wikipedia, it is configured to disallow anonymous editing and account creation, and impose a stricter autoconfirmed threshold (90 days / 100 edits) for users with IP block exemption editing through Tor.

Proposal to create ProxyBlock
To reduce the abuse and disruption, I propose creating a MediaWiki extension that will automatically apply restrictions to users editing via anonymizing proxies. Since no publicly available list of anonymizing proxies exists, the extension will be integrated with an external service such as IPQualityScore or MaxMind. They offer an API or a downloadable list of IP addresses updated daily. The accuracy of these services looks very good but would need to be tested extensively prior to implementation.

The extension would aim to impose the same restrictions as TorBlock, in line with the current practice of blocking anonymizing proxies on sight.

Benefits
By significantly increasing the barrier to entry for using anonymizing proxies, the change would:
 * reduce vandalism and spam,
 * reduce sockpuppet abuse, and
 * restrict sockpuppeters to a smaller range of IP addresses, thus increasing the effectiveness of the CheckUser tool.

Cost

 * The external services charge a subscription fee, but it's a rounding error of a rounding error of WMF's operating costs.

Implementation
Assuming we use the MaxMind's downloadable database, this would require very little developer time. Almost all of the required code is already there in the form of the TorBlock extension.

Discussion

 * Wikipedia_talk:WikiProject_on_open_proxies