Dyrr

Dyrr is a join policy for Valheim servers. A character that has played on other worlds, that has used cheats, or that arrives with mods the server does not permit can be refused when it connects. Nothing is refused until an admin turns Enforce on.

It also kicks idle players on dedicated servers, reports when a character comes back carrying something it did not leave with, and stops your own client from taking a character into a world it does not belong to.

Features

• Six checks at the join: the character has spawned in another world, the game has flagged it for cheats, it has run a console command the game classes as a cheat, its own records disagree with each other, the client is running mods the server does not permit, or it did not answer at all. Each can be switched off on its own.
• Enforce is off by default. Every connection is still judged and the verdict is written to the log, so you can see who would be turned away before anyone actually is.
• A refused player is told which rule they broke, on their own screen if they have Longhouse Core, and in their own log either way.
• Character protection on the client: a character is bound to the first world it plays in, and the game refuses to start it anywhere else. This works whether or not the server runs Dyrr.
• Idle kick on dedicated servers, with a chat warning first.
• Inventory watch: a log line when a character's inventory changed while it was offline. This only ever reports. It never refuses or kicks.
• A dyrr console command that prints the standing verdict for everyone currently connected.

How the join check works

Both ends register an RPC as soon as the connection object exists, before either side sends PeerInfo. The client sends what it knows about its own character: the character name, the cheats flag and its counter, the name of every console command the character has ever run, the UIDs of every world it has spawned in, and the BepInEx plugin GUIDs loaded on that machine. The server does the arithmetic in a prefix on ZNet.RPC_PeerInfo and refuses before the player spawns, so a refused player never watches the world load first. All of it comes out of PlayerProfile, which lives on the client's disk, so all of it is self-reported. See Known limits.

Which console commands count as cheats is decided on the server, from the server's own Terminal command table, so a cheat command added by some other mod on the server counts for free. A dedicated server has no guarantee of having built that table when the first player knocks, so there is a fallback list of the 73 vanilla commands registered with isCheat: true.

The mod check is the one that reaches cheating on a dedicated server. Console.IsCheatsEnabled() returns ZNet.instance.IsServer(), so a client's own devcommands does nothing on someone else's server. Anyone cheating there is running a mod that patched around that line, which makes "what is this client running" the more useful question.

The tamper check does not need the client to be honest, only consistent. The game writes the same facts in more than one place: m_usedCheats is a bool, PlayerStatType.Cheats is a counter incremented on the next line, and m_knownWorlds records worlds by name at save time where m_worldData records them by UID at spawn. A flag that is clear beside a counter above zero, or more world names than world UIDs, is an edited save. Neither inequality can be produced by playing the game.

Character protection

Refusing a character at the join arrives too late to help it. Loading a character into any world writes that world into PlayerProfile.m_worldData permanently, and nothing in the game ever removes the entry. So the client half refuses the trip instead.

Each character is bound to the first world it is seen in, recorded in BepInEx/config/dyrr-home.txt. After that:

• Starting a local world with a character bound elsewhere is refused at FejdStartup.OnWorldStart, with a popup naming both worlds and the file to edit.
• Joining a server whose world is not the character's home is dropped inside RPC_PeerInfo, before the character spawns and before the game writes anything. This works whatever the server does, and whether or not the server runs Dyrr at all. That is ProtectOnServers.

Neither asks for confirmation. The damage has no undo, so a confirm dialog would just be a button for doing the unfixable thing.

The character select screen carries the answer under the character's name, in a clone of vanilla's own "Cloud save" label: Belongs to <world>, Not bound to a world yet, Has played in <world> and <world> for a character that already has more than one, or Belongs to a world that is not on this PC when the world is a server's. The line follows ProtectCharacter and disappears with it.

A character with exactly one world in its own save is bound on the spot even if Dyrr has never watched it play. A character with more than one is left unbound, since there is no single home left to defend, and those are exactly the characters an enforcing server turns away.

Idle kick

On dedicated servers only. A player whose character has not moved 5cm or turned one degree for IdleMinutes is kicked, after a chat warning IdleWarnMinutes ahead. Position and facing are read off the character's ZDO every five seconds. Walking, fighting, turning the camera or sorting a chest all reset the clock.

The kick itself is vanilla's own InternalKick, the same path the console command takes, so the player gets the ordinary kicked screen with a reason attached. A locally hosted world is never watched.

The warning needs Core 1.2.5 or newer, because a dedicated server cannot write into a chat window by itself: the line is sent to that one player and their Core draws it. Without Core, or on an older one, the kick still happens and the warning is only in the server's log. It is said in the ordinary voice rather than as a shout, since it is meant for one person.

Inventory watch

A player's inventory never crosses the wire in vanilla: it lives in their own .fch on their own disk. So the client sends a tally of what it is carrying every InventoryInterval seconds, the server keeps the most recent one, and compares the first report of the next session against it. What that catches is a change made while the character was away, rather than ordinary play.

The line names what moved, biggest movement first. Item names are the game's own localisation tokens, and anything above quality 1 carries its level:

Inventory changed while away: Balder, +40 $item_iron, +12 $item_silverore, +1 $item_sword_iron*4

Two honest sources of false alarms: a client that crashes stops sending, so the stored snapshot can be up to one interval stale, and Valheim can itself roll a character back to its own last local save. Both look identical to tampering at the moment the report arrives, which is why this only ever writes a log line. Nothing here can refuse, kick or correct anybody.

Installation

Through a mod manager, install Dyrr and it is done. By hand, put Dyrr.dll in BepInEx/plugins/Dyrr/.

• Requires BepInEx 5.4.2350. BepInEx 5 API only, not compatible with BepInEx 6.
• Longhouse Core is an optional soft dependency. See Multiplayer.
• Install it on the server and on every client. The facts being judged live on the client, so a client without Dyrr answers nothing, and RefuseUnreported is on by default.

Start the game or the server once and quit. That first run writes BepInEx/config/ezomic.valheim.dyrr.cfg, which does not exist until the plugin has loaded. This is the usual reason people think the mod is broken.

Built against Valheim 1.0.7. Version 1.4.0 does not run on pre-1.0 Valheim, and 1.3.0 does not run on 1.0.

Before you turn Enforce on

Read this part. Enforce is the one setting here that can lock people out of a server, including you.

• The game never removes a world from a character's record. One visit anywhere else is permanent for that character file. Restoring a backup taken before the trip is the only way back in, and it does work: a character refused for having travelled came back from backup and was admitted.
• The cheat flag is the same. devcommands sets it and nothing clears it.
• Being an admin does not exempt you. Dyrr does not consult adminlist.txt anywhere. Your own character is judged by exactly the same rules as everybody else's.
• With Enforce on, a client without Dyrr is refused by RefuseUnreported. If you are running Core as well, its version check turns that client away first.
• Every server you run must enforce. A lenient server is a hole a bound character walks into, and the lenient one is what ruins it. Keep a separate character per server.

The order that works: leave Enforce off, let people connect, run dyrr and read the log, put the innocent plugins in dyrr-mods.txt, then turn Enforce on.

ProtectCharacter is on while Enforce is off. Refusing other people is a policy somebody should choose; refusing to let you ruin your own character is not.

Configuration

BepInEx/config/ezomic.valheim.dyrr.cfg. Every entry carries its own comment in the file.

Door (server side)

Protect (client side)

Mods (server side)

Notice exists because Enforce is a single switch over every rule at once. Trialling the mod list by turning Enforce off also stops refusing cheats and altered records for as long as the trial runs. Use Notice for a week, read the log, then set Refuse.

The plugins the server itself runs are always permitted and never need listing, so adding a mod to the server does not refuse everybody the next day. A value that is none of the three words is read as Refuse and logged, so a typo cannot be the thing that opens a server.

Inventory

Idle (dedicated servers)

BepInEx writes every entry to disk on the first run, and the saved value beats a new default in code. If a setting appears to do nothing after an update, check the .cfg before anything else.

Files Dyrr writes

All three live in BepInEx/config/, as plain text.

dyrr-home.txt (client). One line per character: playerId|worldUid|character|world. Only the two numbers are read; the names are there so you can recognise the line. Delete a line to unbind that character. The file is re-read whenever it changes, so you can edit it with the game running. Editing it can only damage your own character, which is why it is not defended.

dyrr-mods.txt (server). The allowlist, one GUID per line, # for comments. Written with its own explanation the first time Dyrr looks for it. It is re-read whenever it changes, so letting one friend keep their map mod takes effect on the next connection rather than at the next restart. AllowedMods in the .cfg still works and is added to this, but BepInEx never reloads a .cfg on its own, so that entry costs a server restart and everybody online.

dyrr-inventories.txt (server). The last inventory snapshot per character. Safe to delete; you lose the next comparison and nothing else.

Console commands

The console needs Valheim's -console launch argument on a client. A dedicated server has one already. None of these are cheat commands and none are admin gated: the report is the server's own state to whoever is already at its console, and the bindings are the local machine's own file.

dyrr forget does not undo anywhere the character has already been. The game's record of that is permanent and no mod can clear it.

On a server, dyrr prints something like:

Dyrr 1.4.0
World: 'midgard' (-4881...)
Enforce is OFF - failures are reported here and refused to nobody.
Checks: other worlds on, cheats on, cheat commands on, tampered on, unreported on
Mods: Allow (Refuse) - 12 permitted here
Refused so far this session: 0

  Ragnar  admitted
  Sigrun  would refuse: has played on 2 other world(s)

The same block also goes to BepInEx/LogOutput.log, because a console scrolls and a log file does not. On a client it reports what that machine knows instead: whether a server has refused it this session, and why, plus the local bindings.

Every plugin a joining client brings that the server does not run or allow is logged as it connects, admitted or refused. That line is what you build the allowlist from:

A client brought 2 plugin(s) this server does not run or allow: randyknapp.mods.equipmentandquickslots, ...

A refusal names who it was, by character name and by the platform id off the socket:

Refused a connection: Balder (76561198662440314) has played on 1 other world(s)

Multiplayer

Install Dyrr on the server and on every client. The server decides everything; the client only answers the question and protects itself.

Longhouse Core is optional and the join check works without it. Two things are lost when it is not installed:

• The version check. Core compares each Ezomic mod's version and build id when a client connects and makes the server reject mismatches. That matters more here than elsewhere, because the facts being judged are reported by the client, and an old build of Dyrr answering an unfamiliar question is exactly what the version check would have caught. A report in a format this build cannot read is treated as unreported rather than guessed at.
• The refusal screen. Valheim's kick screen carries no text of its own. Core is what puts the reason on it. Without Core, a refused player gets a generic screen and the reason in their own BepInEx/LogOutput.log.
• The idle warning. A server has no way to write into a player's chat window on its own, so the warning before an idle kick goes through Core 1.2.5 or newer. Without it the kick is unannounced and the warning exists only in the server log.

With Core installed, Dyrr registers at Requirement.Everyone, so Core requires the plugin on both ends. Core also applies the host's config values on connected clients in memory, without writing their config file.

What a refused player sees. With Core: This server refused this connection. It has played on 2 other world(s). on the kick screen, and the same line in their log. Without Core: the stock kicked screen, and the line in their log. A refusal by the client's own protection is different again: a local world gets a vanilla popup naming both worlds and the file to edit, while a stopped server join gets a plain disconnect screen, with the reason on it only when Core is installed.

Known limits

• Everything the client reports is self-reported, the plugin list included. A purpose-built client can lie about all of it. More records only raise what a liar has to keep straight.
• A cheat that never touches the console leaves no mark. Confirmed here rather than reasoned about: a god mode toggle that calls Player.SetGodMode directly writes none of the four records the character checks read, so those checks correctly find nothing. RefuseMods is what sees that client, by its plugin GUID.
• RefuseTampered has never fired in practice. Producing a profile whose own records disagree takes deliberate editing nobody here has done. It cannot be tripped by playing the game wrong, so the risk is that it never fires rather than that it fires wrongly.
• The inventory watch can raise a false alarm after a crash. See that section.
• If Dyrr cannot read PlayerProfile.m_worldData at all, it says so once at error level and judges nobody on travel, rather than reading an unreadable list as an empty one. Both travel rules go quiet together and the server logs that it is judging without them.

Troubleshooting

There is no config file. The plugin has to load once before BepInEx writes it. Start the game or the server, quit, look again.

A setting has no effect. BepInEx saved the old value on first run and it beats the new default. Edit the .cfg, not just the docs.

Nobody is being refused. Enforce is off by default. Run dyrr to see what the checks are set to and what the verdict on each connected player is.

Your own client is refused for mods. A server does not run the tools you develop with. Put their GUIDs in dyrr-mods.txt.

The character select line is missing. It follows ProtectCharacter. With that off there is nothing being enforced for it to describe.

A restored backup carries a stale home. Backups do not touch dyrr-home.txt, which lives beside the config rather than with the character. Use dyrr forget <id> or delete that character's line.

Upgrading from Threshold. Dyrr was called Threshold until 2026-08-18. On the first run it copies ezomic.valheim.threshold.cfg to its new name and adopts threshold-home.txt (and boon-home.txt before that) if dyrr-home.txt does not exist. Both originals are left in place. Confirmed on a real run, config and bindings intact.

Status

Run against a real dedicated server in both directions: it refuses a character that has been elsewhere, with the reason on the client's own screen and in its own log, and it admits a clean character on an enforcing server. Both cheat checks have fired on a deliberately flagged character. Backup recovery, the menu guard's binding and the migration from the Threshold-era files are all confirmed. RefuseTampered is the one check that has never seen the thing it looks for.

1.4.0 is the Valheim 1.0 rebuild. The achievements system turned PlayerProfile's single stat record into an array of ten and moved the known-worlds and known-commands lists inside it, and the cheat counter is now resolved by name rather than by the ordinal the compiler baked in. Full history in CHANGELOG.md.

Bug reports

The Discord is the fastest route, and the right one if you are not sure whether what you are seeing is a bug. Issues on the repo work too and suit anything long.

Bring BepInEx\LogOutput.log from whichever end saw the problem, and say whether you were on a server or in single player. If a refusal is wrong, the dyrr output and the character's line from dyrr-home.txt are the two things that settle it. If a vanilla mechanic broke, check AppData\LocalLow\IronGate\Valheim\Player.log as well, because gameplay exceptions land there rather than in the BepInEx log.

Discord

discord.gg/hJzAVaZ5wb is where mod information, updates, support, bug reports and compatibility questions go. There is also a small EU server running the pack if you want somewhere to play. Details are in the Discord.

Licence

MIT. See LICENSE.

Robbin Thijssen / Thijssen Software.

Part of Longhouse

Dyrr is one of the mods in the Longhouse pack, which pins exact versions of its members. You do not need the pack to use this, and it behaves the same on its own.