Fiw AntiCheat

Professional mod verification, modpack enforcement, and admin investigation tools for Minecraft servers.

Fiw AntiCheat helps server owners deal with unwanted client mods without guessing what players are running. On join, the server challenges the client companion mod, records the reported mod list, checks it against configurable rules, and gives admins readable tools for enforcement, rollout, and investigation.

This is built for real server administration: blacklist known unfair mods, audit suspicious resource packs, enforce an official modpack with a whitelist, monitor detections before kicking, and keep per-player profiles so staff can see what changed over time.

Why Fiw AntiCheat?

Most anti-cheat setups focus only on movement or combat behavior. Fiw AntiCheat focuses on client mod visibility and modpack integrity:

• Detect common unfair mod categories such as cheat clients, x-ray, fullbright, freecam, autoclickers, and schematic printers
• Audit active and inactive resource packs, including x-ray/fullbright packs left installed under common names
• Enforce an official modpack list for private SMPs, events, staff servers, and modded communities
• Keep readable player profiles with noisy loader/API entries separated from real installed mods and resource packs
• Let admins roll out rules safely with monitor-only mode before kicking players
• Work across Fabric, Forge, and NeoForge targets with one shared rule engine

Fiw AntiCheat is an admin enforcement tool and mod verification layer. It is not magic and does not claim to be cheat-proof: a malicious custom client can lie. It is designed to make honest clients enforceable, catch common unwanted mods, and give staff practical visibility.

Supported Targets

Loader Minecraft Status Fabric 1.21.1 Active NeoForge 1.21.1 Active Fabric 1.21.11 Active NeoForge 1.21.11 Active Fabric 1.20.1 Active MinecraftForge 1.20.1 Active

NeoForge does not publish a real Minecraft 1.20.1 artifact on the current NeoForge Maven, so the 1.20.1 Forge-family build targets MinecraftForge 47.x.

Features

• Blacklist mode - allow normal mods while blocking selected unfair categories
• Whitelist mode - enforce a captured official modpack list
• Built-in signature database - detects known unfair mods by id and stable markers such as packages or mixin configs
• Admin profiles - view each player's current mods, platform/loader entries, and recent changes
• Resource pack auditing - log active and inactive packs, plus added/enabled/disabled/removed history
• Optional resource pack bans - flag by exact pack id/name or SHA-256 fingerprint, with kicks disabled by default
• Readable grouping - Fabric, Forge, NeoForge, API, and loader noise is separated from player-installed mods
• Monitor-only rollout - log and alert staff without kicking while tuning your rules
• Staff alerts - online operators can see detections as they happen
• Bypass list - exempt trusted accounts or test users by name or UUID
• Tiered exemptions - grant bypass, silent, monitor, quiet_kick, a pinned preset, or force_block per player, with optional expiry and admin-defined auto-escalation rules after repeated detections
• Floodgate/Geyser support - optional Bedrock-player exemption when Floodgate is present
• Hot reload - reload config and signatures without restarting
• Server snapshots - capture the server or an online player as the official whitelist baseline

Commands

All commands require permission level 4.

Command Does /fiwmods reload Reload config and bundled signatures /fiwmods snapshot server Capture the server's loaded mods into the whitelist /fiwmods snapshot player <name> Capture an online player's reported mods into the whitelist /fiwmods profile <name> Show grouped current mods, resource packs, and recent profile history /fiwmods exempt add <player> <tier> [hours] [preset] Grant an exemption tier, optionally with an expiry and a preset name /fiwmods exempt remove <player> Remove any exemption for a player /fiwmods exempt list List all active exemptions

Configuration

The config is generated at:

config/fiw-mods-api/config.json

The internal config folder keeps the original id for compatibility, even though the public mod name is Fiw AntiCheat.

Main options:

Option Purpose mode blacklist or whitelist detection.preset strict, balanced, lenient, or custom detection.monitor_only Log detections without kicking detection.allow_overrides Allow specific signatures/categories even if preset blocks them detection.banned_mods Add exact mod ids to block resource_packs.log Record active/inactive resource packs in profiles resource_packs.kick_on_banned Kick for configured pack matches; default is log-only resource_packs.banned_packs Add exact pack ids or display names to flag resource_packs.banned_fingerprints Add exact SHA-256 pack hashes to flag renamed packs exemptions.bypass_players Full bypass for specific names or UUIDs (no scan at all) exemptions.player_overrides Per-player exemption tiers granted via /fiwmods exempt add (silent, monitor, quiet_kick, preset, force_block), with optional expiry exemptions.escalation_rules Auto-apply a tier after a player racks up repeated detections in a time window whitelist.official_mods Official modpack snapshot used in whitelist mode

Requirements

Target Requirements Fabric 1.20.1 Fabric Loader, Fabric API, Java 17 MinecraftForge 1.20.1 Forge 47.x, Java 17 Fabric 1.21.1 Fabric Loader, Fabric API, Java 21 NeoForge 1.21.1 NeoForge 21.1.x, Java 21 Fabric 1.21.11 Fabric Loader 0.19.2+, Fabric API 0.141.4+1.21.11, Java 21 NeoForge 1.21.11 NeoForge 21.11.x, Java 21

Install Fiw AntiCheat on the server and on player clients. The client companion is what reports the mod list and resource pack state to the server.

Best Uses

• Private SMP modpack enforcement
• Event servers where everyone must use the same mod list
• Staff visibility into suspicious or changing client setups
• Blocking common unfair utility mods without locking down harmless QoL mods
• Auditing players who briefly enable, disable, or delete suspicious resource packs
• Gradual anti-cheat rollout with monitor-only logging before enforcement

Documentation

Full English documentation ships with the mod in DOCS_EN.md: the join protocol, complete config reference, both modes, the signature database, commands, per-player profiles, and troubleshooting.

License

Fiw AntiCheat is released under the Fiw AntiCheat License (Attribution, Non-Commercial). You are free to use, modify, fork, and redistribute it — including modified builds — as long as you give clear, visible credit to the original creator (Fi3w0) with a link back and keep existing notices intact. You may not sell it or any fork without written permission (running it on a server, even a monetized one, is fine). Fi3w0 retains authorship of the original work.

Contact: Discord fi3w0.

Contact me: @Fi3w0 on Github/Discord

Made by Fi3w0 — built for a private SMP, shared with everyone.