Banner image of Firefox 85 introduces 'Network Partitioning' for improved tracking resistance

Firefox 85 introduces 'Network Partitioning' for improved tracking resistance

Firefox 85 introduces “Network Partitioning,” which is part of the “client-side storage partitioning.” Modern web browsers heavily rely on caching content to offer a fast browsing experience. However, shady websites can misuse caching mechanisms to identify and track users.

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The “client-side storage partitioning” (aka “cache partitioning”) isolates the cache belonging to website A from the cache belonging to website B. The isolation ensures that B can’t query for cached content of A to see whether the user visited website A before. Apple’s Safari and Google’s Chromium already partially partition their caches.

In Firefox 84, you can already enable the “Network Partitioning.” Go to about:config, and set “privacy.partition.network_state” to True. While the isolation of these resources can improve your tracking resistance, it might negatively impact your web browser’s browsing performance.

Firefox 85 partitions the following network resources:

  • Alt-Svc
  • Connection pooling
  • CORS-preflight cache
  • DNS
  • Favicon cache
  • Font cache
  • HSTS (HTTP Strict Transport Security)
  • HTTP authentication
  • HTTP cache
  • Image cache
  • Intermediate CA cache
  • OCSP (Online Certificate Status Protocol)
  • Preconnect
  • Prefetch
  • Speculative connections
  • StyleSheet cache
  • TLS client certificates
  • TLS session identifiers
This list is only a subset of client-side states in modern web browsers. Go to the "Client-Side Storage Partitioning" website below to see further client-side states that websites can misuse for tracking.

The successor Firefox 86 implements another subset of “client-side storage partitioning,” called “Dynamic State Partitioning.”

On a final note, keep in mind that most “privacy checks” don’t check these client-side states. Therefore, even if a check says that websites can’t easily track your web browser, the actual tracking websites might be able to track you if they evaluate these unique states.

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