GyattAntiCheat

A lightweight client-server anti-cheat and mod synchronization tool for Valheim. Process scanning is handled asynchronously on a background thread to avoid frame drops or stuttering during gameplay.

Features

• Server Mod Synchronization: Automatically cross-checks client BepInEx plugins against the server's installed plugins. Detects both unauthorized extra mods and missing required server mods.
• Admin Bypass: Players listed in the server's adminlist.txt automatically bypass mod restrictions, process scans, and state checks.
• Detailed Server Logging: Logs player connections, installed mod lists, verification status, and violations (with SteamID/HostName) directly to the server log.
• Background Process Check: Periodically checks for common third-party cheat tools (e.g., Cheat Engine, WeMod) off the main thread.
• State Monitoring: Detects unauthorized use of God Mode, Ghost Mode, Debug Fly, and abnormal movement speeds.
• Client Enforcement: Kicks non-admin players who join the server without the mod installed.

Configuration

The configuration file (com.valheim.gyattanticheat.cfg) is generated in BepInEx/config/ after the first launch:

[ModSync]

• EnforceServerModWhitelist (Default: true): Blocks players from using any mod not installed on the server.
• CheckMissingServerMods (Default: true): Blocks players who are missing mods installed on the server.
• AllowedClientOnlyMods: Comma-separated list of Mod GUIDs/Names allowed on clients even if not on the server.
• ServerOnlyMods: Comma-separated list of Mod GUIDs/Names installed only on the server that clients are not required to have.

[Security]

• BlacklistedKeywords: Comma-separated list of restricted process names or mod keywords.
• AutoKickCheater (Default: true): Automatically kick non-admin players when a violation is detected.
• RequireGyattAntiCheat (Default: true): Require clients to have this mod installed to stay connected.
• MaxSpeedThreshold (Default: 28): Maximum allowed horizontal movement speed before triggering an alert.

Installation

1. Install BepInExPack Valheim.
2. Extract GyattAntiCheat.dll into your Valheim/BepInEx/plugins/ folder (must be installed on both server and clients).