koumodgp

A server integrity and mod-compatibility plugin for dedicated Valheim servers.

koumodgp helps server admins keep their community consistent and fair. It verifies that every connecting player is running the mod set the server expects, and helps admins spot tampering. It is designed for legitimate server administration — it is installed and configured by the server owner, and every check it performs is in service of protecting that server's players.

The same koumodgp.dll is installed on the server and on clients; it detects its role at runtime (like AzuAntiCheat and other ServerSync-style plugins), so there is only one file to distribute.

What it does

• Mod whitelist — clients report their loaded BepInEx plugins; the server compares them to an admin-defined allow list and disconnects mismatches. Supports required and optional mods.
• Integrity check — detects code from unauthorized third-party injectors that patch the game at runtime (a common way cheats are added to a modded client).
• State audit — checks a small set of well-known game flags (god mode, fly, ghost, free build) that external trainers toggle. These are never set for a normal player.

Install

1. Put koumodgp.dll in BepInEx/plugins/ on the server and on each client.
2. Start the server once. It creates BepInEx/config/koumodgp.cfg and, under BepInEx/config/koumodgp/, allowed_mods.txt and signatures.txt (both start empty with examples).
3. Fill in allowed_mods.txt with the mods your server allows (guid=version, guid=* for any version, or ?guid=version for optional mods).

Admin commands (server console, admins only)

kougp status                     connected players + verification state
kougp list                       current allowed mods
kougp reload                     reload config + lists and push to clients (no restart)
kougp allow add <guid> [ver]     add an allowed mod (also: remove)
kougp kick <name> | ban <name>   manual moderation

Notes

• Admins are exempt — anyone on the server's adminlist.txt is never checked.
• Detections kick by default; bans are a manual admin action only.
• Optional Discord webhook posts a generic notice and admin/lifecycle events. Full detail is kept in a local violations.log for the admin.
• Like any client-reported system, a determined attacker who modifies the client can attempt to evade it. koumodgp raises the effort required; it is one layer of a server's defenses.