Add decompressed-bytes-per-second rate limit, update packet limiter defaults - #1786
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electronicboy merged 4 commits intoMay 24, 2026
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R00tB33rMan
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This reverts commit 9890c42.
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…efaults (PaperMC#1786) * Add decompressed-bytes-per-second packet limiter, update defaults * Revert "Add compression ratio limiter"
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The
packets-per-secondlimit was introduced to mitigate compression bomb attacks, where an attacker floods the proxy with small packets that decompress to the maximum allowed size. It's the wrong metric for this, though: 500 packets/s at 2 MiB each is 1 GiB/s of decompressed data, which kills the proxy just as effectively. At the same time, legitimate clients with chatty mods (e.g. heavy plugin-message traffic) were getting disconnected despite consuming far less than any attacker would.This PR adds a
decompressed-bytes-per-secondlimit to[packet-limiter], applied after decompression inMinecraftCompressDecoder. This directly measures what was causing OOM issues, rather than using a proxy metric. With a default of 5 MiB/s over a 7-second window (35 MiB of headroom per window), legitimate clients should never get close to this limit, while any compression bomb is caught well before it causes memory pressure.Default config changes (config version
2.7->2.8):packets-per-second: 500 -> -1 (disabled)bytes-per-second: unchanged (-1)decompressed-bytes-per-second: new field, defaults to 5242880 (5 MiB/s)A migration for this has also been added, overriding the previous defaults if the config version was
2.7or older, including comments explaining each metric.Ported from GemstoneGG#871.