The unintended consequences of blocking IP addresses

Cloudflare have a nice blog post about blocking IP addresses

In late August 2022, Cloudflare’s customer support team began to receive complaints about sites on our network being down in Austria. Our team immediately went into action to try to identify the source of what looked from the outside like a partial Internet outage in Austria. We quickly realized that it was an issue with local Austrian Internet Service Providers.

But the service disruption wasn’t the result of a technical problem. As we later learned from media reports, what we were seeing was the result of a court order. Without any notice to Cloudflare, an Austrian court had ordered Austrian Internet Service Providers (ISPs) to block 11 of Cloudflare’s IP addresses.

In an attempt to block 14 websites that copyright holders argued were violating copyright, the court-ordered IP block rendered thousands of websites inaccessible to ordinary Internet users in Austria over a two-day period. What did the thousands of other sites do wrong? Nothing. They were a temporary casualty of the failure to build legal remedies and systems that reflect the Internet’s actual architecture.

Today, we are going to dive into a discussion of IP blocking: why we see it, what it is, what it does, who it affects, and why it’s such a problematic way to address content online.