The 16‑kilobyte curtain. How Russia’s new data‑capping censorship is throttling Cloudflare

What happened 

Since around June 9, internet users across Russia have experienced significant problems accessing websites that rely on the U.S. web infrastructure giant Cloudflare. At its peak between June 13 and 15, overall traffic from Russia to Cloudflare’s network was cut in half.

The disruption is not a simple on-or-off block, but a more nuanced form of nationwide traffic shaping. According to technical experts, internet service providers across the country have begun implementing a rule that limits data transfers from sites using Cloudflare to just the first 16 kilobytes. This technique is relatively subtle but effective: very lightweight, basic websites can still load, creating a façade of normal internet function, while modern, media-rich sites are effectively broken.

The new measures target Cloudflare, the world’s most popular service of its kind, which provides security and performance tools to as much as 20% of the entire internet. Mediazona has contacted Cloudflare’s press team but has not yet received a response.

Analysts report that similar throttling is also being applied to other major western hosting providers popular with Russian users, including Germany’s Hetzner and the US-headquartered DigitalOcean.

This new wave follows earlier disruptions. In late May, users reported problems accessing the major French cloud computing company OVH, with blocks specifically targeting the UDP protocol. This protocol is key for real-time heavy applications like online gaming, and the filtering immediately led to reports of inaccessible servers for the Steam gaming platform. The filtering also affects peer-to-peer technologies like the BitTorrent DHT network, a system that helps users find each other without a central server and has been subject to intermittent interference since 2021.

What caused this

While Russia’s censorship agency, Roskomnadzor, has not issued a formal statement on the throttling, experts suggest the move is part of a broader strategy with several overlapping objectives.

One primary goal is to combat the tools used to circumvent state censorship. Hetzner and DigitalOcean are widely used by Russians to host private VPN servers, which allow them to bypass the Kremlin’s ever-widening blocklists. Cloudflare’s infrastructure is similarly used by established anti-censorship services like Psiphon. By degrading these core providers, the state can disrupt the ecosystem of circumvention tools without having to block each one individually. The interference with torrents may also be a side effect of broader filtering aimed at common VPN protocols like WireGuard.

A second objective is to accelerate the forced migration of Russian companies to domestic, state-controlled technology providers. This aligns with Russia’s long-standing “landing law,” which requires foreign tech firms to establish a formal presence in the country and cooperate with authorities. In April, Roskomnadzor threatened to block providers who failed to comply with the law. By making reliable foreign services unusable, the state creates a powerful incentive for businesses to switch to Russian alternatives that are fully compliant with government surveillance mandates.

However, Russia simply does not have the domestic capacity to replace the services of a global leader like Cloudflare. The company is one of the world’s most important providers of protection against DDoS attacks. Blocking it not only forces Russian companies onto more expensive and less capable local services, but also paradoxically makes them more vulnerable to attack by removing a key layer of defence.