GeyserAC

Description

Anti-cheat for Bedrock players who join a Java server through Geyser. Java anti-cheats like GrimAC skip Geyser players entirely, so without something on the Geyser side a Bedrock client can fly, speed and reach freely.

GeyserAC is a Geyser extension. It runs its own copy of Bedrock movement physics for every Bedrock player, checked tick for tick against a real Bedrock Dedicated Server, and sets the player back when the client moves somewhere the physics can't take it.

Features

• Movement: walking, sprinting, sneaking, jumping, swimming, ladders and vines, ice, slime, honey, soul sand, cobwebs, powder snow, scaffolding, bubble columns, beds, elytra and rockets, riptide, effects and knockback. Covers fly, speed, step, jesus, spider, anti-knockback and similar.
• Vehicles: horses, donkeys, mules, camels and boats are predicted too.
• NoFall, Timer, NoSlow, sprint rules (hunger, blindness) and bad inputs.
• Combat: reach (3.3 blocks to the hitbox the client draws, lag compensated), hitboxes (the look has to meet the target), attacks through walls, attacking while using an item.
• Blocks: placement and break reach and aim, clicks through walls, FastBreak, nuker, fast place, invalid block faces. Bedrock's Haste is stronger than Java's, so the Haste level shown to Bedrock clients is lowered to match Java break times.
• Inventory: clicking items while moving with a screen open, attacking with a screen open.

Keyboard, controller and touch input are all handled. Lag compensation uses a ping sent with every batch of changes, so a change (speed, effects, knockback, a block update) only counts once the client has actually seen it.

GrimAC Compatibility

Made to run next to GrimAC. Grim checks Java players and skips every Geyser player (it can't predict Bedrock movement), and GeyserAC only checks Geyser players. Together every player is covered, and they never both act on the same player. No config needed on either side.

Installation

1. A server with Geyser 2.12 or newer (tested on Geyser-Fabric; Floodgate optional).
2. Put the jar in Geyser's extensions/ folder (config/Geyser-Fabric/extensions/ on Fabric) and restart.
3. Create an empty file named enforce in extensions/pandageyserac/ to turn setbacks on. Without it the extension only logs. The file is checked while the server runs.

Flags and setbacks show up in the server log as [pandageyserac]. An empty verbose file in the same folder writes every tick to moves.log (large, for debugging).

Acknowledgements

The packet hook, chunk decoding and Bedrock block shapes are adapted from Boar and Geyser (both MIT). Collision data from minecraft-data.

Try it out

hardcoreanarchy.gay (Deathban Anarchy)
sky.hardcoreanarchy.gay (Skyblock Anarchy)

More mods

• Anti-Exploit - A drop-in mod for preventing common exploits. Fully configurable and works well alongside other anti-cheats like GrimAC.
• Occlusion - Server-side anti-freecam. Prevents players from seeing caves, ores and entities they can't see.
• Dupe Fix - A simple drop-in mod to prevent all forms of duping. TNT-Duping, Gravity block duping, and much more will not work with this mod enabled.
• No Lag - Stop common causes of lag on your server. Configure to your likings.

All my mods

Issues

Bugs and problems go on GitHub Issues. There is no Discord support.

License

MIT