ItsAC

ItsAC – a lightweight, packet-based anti-cheat for Minecraft 1.8.8

Built on PacketEvents • Lag compensated • 27 checks • Zero false positives in testing

▌ About

ItsAC is a modern anti-cheat written from scratch for PvP and survival servers. Instead of relying on Bukkit events, it reads raw packets through
PacketEvents and reproduces the
1.8 client physics to tell legit players apart from cheaters.

Every movement check uses the same math as the vanilla client (gravity, friction, jump height), so instead of loose "speed limits" you get precise predictions. Combat checks rewind the target's position by the attacker's ping, so laggy players are never punished for the server's delay.

▌ Features

• Transaction-based ping – exact latency and knowledge of when the client applied velocity or a teleport
• Lag compensation – reach & hitbox checks use a 2-second position history of every player
• Setbacks – flagged players are pulled back to their last legit location
• Anti-setback-bypass – clients that ignore teleports are detected
• Anti-crasher – NaN / infinite / out-of-world positions are cancelled instantly
• Fully configurable – every check can be toggled, with its own max VL, punishment command and setback option
• Violation decay – VL slowly drops over time, so one-off flags don't add up
• Async & lightweight – checks run on the player's network thread; no heavy main-thread work

▌ Checks

Movement

• Fly A – vertical motion that breaks 1.8 gravity (Fly, Glide, Hover)
• Fly B – jumps higher than allowed (HighJump, Step)
• Speed A – horizontal speed prediction with friction, sprint-jump and knockback
• NoFall A – spoofed ground state (NoFall, packet Criticals)
• Timer A – game speed manipulation

Combat

• Reach A – lag-compensated attack distance
• KillAura B – attacks without looking at the target (hitbox ray-trace)
• KillAura C – NoSwing
• KillAura D – multi-target aura & AutoBlock
• AutoClicker A / B – CPS limit & inhumanly consistent clicking
• KillAura A, Aim A (experimental, alerts only)

Packets

• BadPackets A–G – invalid pitch, self-attack, duplicated sprint/sneak, invalid slot changes, Blink, sprint while sneaking, ignored teleports

World

• Scaffold A / B – placing on invisible block faces, invalid cursor position
• FastBreak A / B – missing break delay, breaking without starting
• Nuker A – breaking many blocks at once
• BlockReach A – interacting with blocks too far away
• Scaffold C (experimental, alerts only)

▌ Installation

• Download PacketEvents (2.14.0 or newer) and put it in your plugins folder.
• Put ItsAC.jar in your plugins folder.
• Restart the server. The config is generated in plugins/ItsAC/config.yml.

▌ Commands & Permissions

Code (Text):

/itsac alerts          - toggle alerts          (itsac.alerts)

/itsac info <player>   - ping, client version, VL (itsac.admin)

/itsac reload          - reload the config      (itsac.admin)

itsac.bypass           - completely exempt a player (default: nobody)

Aliases:
/ac,
/anticheat

▌ Configuration

Spoiler: Example check section

Code (Text):

checks:

  speed:

    a:

      enabled: true

      alerts: true

      setback: true

      max-vl: 20

      punishment: "kick %player% &cYou were kicked by ItsAC (%check%)"

Several commands can be chained with
;. Placeholders: %player%, %check%, %vl%.

▌ Requirements

• Spigot / PaperSpigot 1.8.8
• Java 8 or newer
• PacketEvents 2.14.0+

Players joining with 1.9+ clients through ViaVersion are supported, but only version-independent checks run for them. Full support for newer versions is on the roadmap.

▌ Roadmap

• ✔ 1.8.8 – full protection
• ⏳ 1.9 – 1.12 (offhand, attack cooldown, elytra)
• ⏳ 1.13 – 1.16 (swimming, new blocks)
• ⏳ 1.17 – 26.x (new movement packets, extended world height)
• ⏳ Mob support for Reach / KillAura

▌ Support

Found a false positive or a bypass? Please post it in the
Discussion tab with the alert message (it includes debug info and ping) –
don't use the review section for bug reports, I can't reply there.

Made with ❤ by Patryk • ItsProject