CrossplayShield Free

By
Tomokisan

Anti-exploit for Geyser cross-play servers: per-packet limits with a Bedrock margin, server settings audit, never kicks Bedrock players.

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CrossplayShield

Anti-exploit for cross-play servers (Paper or Folia with Geyser/Floodgate) that does not kick your Bedrock players.

Geyser turns some Bedrock actions into bursts of Java packets: moving a stack is several clicks, and sleeping in a bed can send hundreds of packets per second (Geyser issue #6775). Packet limiters tuned for Java clients see an attack and kick the Bedrock player. CrossplayShield limits packets per type, gives Bedrock players (detected by Floodgate) a wider margin, and only adds what Paper does not already do.

Measured, not guessed

Peak rates over one second, measured with test bots on Paper 26.3, Folia 26.3 and Paper 1.21.11:

Packet	Bedrock player	Java player	Limit (Java / Bedrock)
Inventory clicks	54 (emptying an inventory into a chest)	108 (inventory sorting mod)	162 / 486
Block breaking	6	—	60 / 180
Block placing	5	—	40 / 120

Walking, sleeping, chests, building and mining: no packet blocked, no kick, on all three servers.

Features

Packet limits per type: inventory clicks, creative inventory, books, signs, anvil renames, plugin messages, bundles, block breaking and placing. Packets up to the limit always go through; only the extra ones are dropped. A player is kicked only after 5 seconds at more than twice the limit
/cs audit: checks your Paper settings (packet limiter, spam limiter, item validation, duplication settings), ViaVersion's packet limiter (which can kick sleeping Bedrock players) and Floodgate, with the line to change
Dry-run mode: see what would be blocked without blocking anything
/cs info <player>: Java or Bedrock, device, packets per second, last blocks
/cs exempt <player> [seconds]: exempt a player for a while
English and French, editable texts, add your own language
Lightweight: about 2 microseconds per packet with 10 Bedrock players in our benchmark

A full edition (9.99 USD) adds creative item cleanup, chunk limits, a command filter, in-game and Discord alerts and a developer API.

Requirements

Paper or Folia 1.21.4 to 26.x, Java 21+ (tested on Paper 1.21.11, Paper 26.3 and Folia 26.3)
PacketEvents 2.14+
Optional: Floodgate, to give Bedrock players their wider margin