How to Set Up an Arma Reforger Dedicated Server

Choose the server shape before you install it

Arma Reforger has two hosting modes. A player-hosted server is a listen server started from Multiplayer > Host inside the game, and that option is only available on PC. A dedicated server is a separate server process with no game instance attached; it only handles game information and network synchronisation, so it is the right choice if you want a proper community server that stays up when nobody is playing.

That is also why renting is often simpler for a small unit that wants results tonight. You avoid port forwarding, most control panels make mod handling easier, and managed hosts commonly apply -maxFPS 60 for you. If you are weighing home hosting against renting, our guide to self-hosting a game server covers the practical trade-offs around power, networking and maintenance.

The best start is to make five decisions up front, because each one changes what goes in config.json and what the server will cost in CPU time, memory, bandwidth or admin effort.

Install the dedicated server files

On Steam, the stable Arma Reforger dedicated server app is 1874900. There is also an experimental app, 1890870. For a community server, stay on stable unless everyone joining is deliberately using the experimental branch as well. Stable reduces avoidable client-version mismatches and keeps your setup predictable after tonight’s first launch.

A minimal SteamCMD runscript looks like this:

@ShutdownOnFailedCommand 1
@NoPromptForPassword 1
force_install_dir ../armar_ds
login anonymous
app_update 1874900 validate
quit

Run it with steamcmd +runscript update_armar_ds.txt. On Windows the server executable is ArmaReforgerServer.exe. On Linux it is ./ArmaReforgerServer. Both platforms work; the main difference for most admins is simply where you prefer to manage files, services and firewalls.

Write one clean config.json

Keep the first config short and deliberate. Leave bindAddress and publicAddress out unless you already know you need them. This example is enough to boot a visible, passworded server with admin access, RCON, crossplay and the official Conflict – Everon scenario.

{
  "a2s": {
    "port": 17777
  },
  "rcon": {
    "port": 19999,
    "password": "ChangeThisRconPass",
    "permission": "admin"
  },
  "game": {
    "name": "My Reforger Server",
    "password": "ChangeThisJoinPass",
    "passwordAdmin": "ChangeThisAdminPass",
    "admins": [
      "YOUR_IDENTITY_ID"
    ],
    "scenarioId": "{ECC61978EDCC2B5A}Missions/23_Campaign.conf",
    "maxPlayers": 32,
    "visible": true,
    "crossPlatform": true,
    "gameProperties": {
      "fastValidation": true,
      "battlEye": true
    },
    "mods": []
  },
  "operating": {
    "lobbyPlayerSynchronise": true
  }
}

Why each block matters:

• a2s is the server query service used for browser visibility on port 17777.
• rcon starts the remote admin service on port 19999. Without a valid RCON password, it will not start.
• game.name is the browser name players see.
• game.password is the join password. This is for entry, not admin rights.
• game.passwordAdmin is the in-game admin password used with #login.
• game.admins is your admin allow-list. Listed users can #login without the password.
• game.scenarioId picks the only scenario the server will run. There is no mission rotation.
• game.maxPlayers sets your slot count. Higher values increase the amount of player state and replication work the server may need to process.
• game.visible controls browser visibility.
• game.crossPlatform decides whether all platforms can join.
• gameProperties.fastValidation should stay true, especially on a public server.
• gameProperties.battlEye keeps BattlEye enabled.
• game.mods is empty on purpose so the first launch only tests the base game.
• operating.lobbyPlayerSynchronise sends the list of connected players with the server’s heartbeat, so the browser shows the real player count. It is on by default; writing it out keeps it visible when you edit later.

Three JSON rules catch most first-time mistakes. Parameter names are case-sensitive, so scenarioId is not the same as scenarioID. Strings such as names, passwords, IDs and scenario paths go in quotes, while booleans and numbers do not. And every comma matters: one trailing comma is enough to stop the server before it finishes reading the file.

If you want to see the scenario paths available on your install, start the server once with -listScenarios; it will log the available .conf paths at startup. A few official examples are below.

Ports, networking and why UDP matters here

Your server uses three main ports. UDP 2001 is the public game port players actually connect to. UDP 17777 is the A2S port, which answers Steam-style server queries from server lists, monitoring tools and bots. UDP 19999 is the RCON port for remote administration.

For a self-hosted server to be reachable from outside your local network, you forward UDP traffic for the ports you are using. In practice, 2001 is the port players cannot do without, 17777 is worth opening so outside server lists and status bots can see you, and 19999 only needs to be reachable if you use remote RCON tools. This is the traffic pattern to keep in mind:

Do not rush to set bindAddress or publicAddress. The normal starting point is to leave them out, which means the server binds openly and lets the backend auto-detect the public address. Set them only when the default behaviour is wrong, most commonly in a Linux container or Docker setup where the server can register the container IP instead of the reachable host IP. In that case, clients see the server but fail to connect until publicAddress and the correct public port are set explicitly.

Two final points save time. Port forwarding here is UDP, not TCP. And IPv6 is not supported, so if your network is relying on IPv6-only assumptions, fix that before spending an hour on the JSON.

Start it with the right launch options

The three startup parameters that matter most on day one are the config path, the profile path and the frame cap. A clean Windows launch looks like this:

ArmaReforgerServer.exe -config ".\config.json" -profile ".\profile" -maxFPS 60

On Linux, the equivalent form is:

./ArmaReforgerServer -config /home/<username>/.config/ArmaReforgerServer/config.json -profile /home/<username>/.config/ArmaReforgerServer -maxFPS 60

-maxFPS matters because, without it, the server can try to consume all available resources. In practical terms that means unnecessary main-thread CPU use, extra heat and less headroom for other processes on the box. A starting value of 60 is sensible because it limits waste without forcing an unusually low cap; if you later tune upward, do it for a reason rather than as a reflex.

The trade-off is simple: a lower cap conserves CPU time, but if it is set too low it can become its own ceiling under load. The way to tell if your setting helped is to watch the logs rather than guess from one player’s feel. Console logs are written to the profile folder, and -logStats can log server FPS at an interval so you can compare busy sessions against quiet ones.

The profile folder matters for more than logs. By default, Workshop add-ons also download there, so keep it on storage you can monitor and back up.

Privacy, browser visibility, admins and RCON

There are three sensible access patterns for a new server. Public and open means visible: true with no join password, which is only wise when the rules and admin cover are already in place. Public but passworded means the server still appears in the browser yet only players with the join password can enter, which is the safest starting point for a small group. Hidden means visible: false, which removes it from the server browser and is useful for testing changes without advertising the server.

Keep the three passwords separate. game.password is the join password for players. game.passwordAdmin is the in-game admin password; open chat with C in the lobby or Enter in-game, then type #login <password>. The rcon.password is for remote admin software, and it is not the same system. Admin and RCON passwords should contain no spaces, and the RCON password must be at least 3 characters.

The matrix below is the quick reference worth checking before you invite anyone:

game.admins accepts IdentityIds and SteamIds, but there are two details that matter. First, the list is limited to 20 unique IDs. Second, only IdentityIds receive the priority join queue benefit, so if reserved access during busy periods matters, collect IdentityIds rather than relying on SteamIds alone.

If you expect the server to fill, use joinQueue.maxSize and slotReservationTimeout deliberately. A join queue (up to 50 places; 0, the default, turns it off) lets players wait in line for a slot on a full server instead of being turned away. slotReservationTimeout (5 to 300 seconds, default 60) decides how long a slot is held for a player who was kicked by a replication error, so they can reconnect without losing their place. The cost is social rather than technical: a long reservation on a busy server means a free slot sits empty while others wait.

For RCON itself, choose the permission level with care. admin can run state-changing commands, while monitor is safer for tools or staff who only need visibility. Command whitelist and blacklist options are there for a reason: they reduce the blast radius if one remote tool or user is misconfigured.

Crossplay and mods: keep the rules clear

Crossplay

There are two clean ways to configure platform access. If you want all platforms, set game.crossPlatform to true and leave supportedPlatforms undefined. If you want a PC-only server, leave crossPlatform false or omitted and let supportedPlatforms stay at its default PC-only setting.

The reason to keep it this simple is that platform rules affect who can see the server as eligible to join. If you are trying to build a mixed-platform community, set crossplay once and make that policy clear. If you want tight control for a PC modding group, keep it PC-only from the start instead of changing course after players settle in.

Mods

The mods array is a list of objects with a modId, a name and, optionally, a version. If you pin a version, the server keeps loading that specific release until you change the JSON. If you omit the version, the server uses the latest version, which is convenient but means a mod author’s update can alter your server overnight.

Clients automatically download and activate required mods when they join, so the server’s mod list is also the gatekeeper for client content. That is why pinned versions are safer for organised groups: you control when the change lands. If a mod is marked with required: false and it fails to download, the server removes that mod with a warning instead of stopping outright; useful for optional extras, not for anything the scenario depends on.

To build the list, activate the mods in-game, open Mod manager, use the JSON tab and copy the block. Then add mods one at a time and read the log after each change. That approach costs a bit more time tonight, but it saves hours of guessing later because each startup failure has one obvious suspect. Keep this flow in mind when deciding whether to pin or update:

Mods increase startup work in three ways: download time, disk activity and content loading. On containers, large mod downloads can also hit temporary write-path issues; if you see Docker-related curl write errors, use -addonTempDir so temporary add-on files land somewhere suitable.

Persistence, AI and the settings that really affect performance

Once the server works, these are the settings worth learning before you blame the machine. Persistence settings control how often state is written to disk and how much of it you keep. autoSaveInterval decides how often session saves happen, while saveRetention decides how many are kept. Shorter intervals reduce lost progress after a crash, but they also mean more frequent disk writes.

playerSaveTime does the same job for player data. Lower values protect recent progress more aggressively, but they cost extra storage activity. loadSessionSave and keepSessionSave matter when you want the server to resume an existing state instead of booting as if fresh every time.

AI settings mostly hit CPU first and memory second. aiLimit lets you put a ceiling on AI count if a scenario’s combat density is overwhelming the simulation thread. disableNavmeshStreaming loads the full navmesh into memory, which can give slightly better AI performance, but the trade-off is a bigger memory footprint, up to hundreds of MB depending on the terrain.

View distance settings affect both gameplay feel and server load. serverMaxViewDistance sets the upper limit for the world view distance, while networkViewDistance caps how far replicated entities are streamed. Lowering networkViewDistance reduces replication work and bandwidth use first; lowering serverMaxViewDistance is the bigger gameplay compromise because it cuts long-range awareness more directly. Keep fastValidation set to true; that is not a performance toggle to play with on a public server.

If you are trying to judge the machine rather than the config, read how game server hardware requirements work before spending money in the wrong place. Arma Reforger load is shaped more by scenario design, AI, replication range and session persistence than by a single headline spec. Bohemia’s own Docker example assigns 4 CPU cores and 6 GB of memory, but that is an example allocation, not a universal requirement.

Keep it running after updates, and troubleshoot by symptom

After game updates, run SteamCMD again with app_update 1874900 validate. The validate step is worth keeping because it catches damaged or partial files instead of leaving you to guess whether the update or the install is at fault. Before major changes, back up both config.json and the whole profile folder so you keep logs, saves and downloaded add-ons together.

If you edit the BattlEye RCon settings in BattlEye\BEServer_x64.cfg, append the RCon port and password instead of editing existing lines. Changing the wrong lines there can produce the player-facing error about missing GameID or MasterPort settings, which looks like a networking problem but is really a BattlEye config mistake.

First-fix troubleshooting table

Should you self-host or rent?

Both can work. The better choice depends less on budget slogans and more on how much networking, patching and fault-finding you want to handle yourself.

If you are comparing managed options, use our Arma Reforger server hosting comparison to check how providers handle access, file management and general admin convenience rather than chasing one headline feature.

Arma Reforger server FAQ

Is the Arma Reforger dedicated server free?

Yes. The dedicated server is Steam app 1874900 and downloads through SteamCMD with an anonymous login, so you don’t need to buy a second copy of the game for the server. What you pay for is the machine, or a rented plan, plus the time to manage updates, ports, saves and mods.

Which ports does an Arma Reforger server need?

The default game port is UDP 2001, the A2S query port is UDP 17777, and the RCON port is UDP 19999. For outside players to find and join a self-hosted server, 2001 and 17777 are the important pair; 19999 is only needed remotely if you want RCON from outside the local machine or network.

How do I make my Arma Reforger server private?

The simplest method is to keep visible set to true but set a game.password, so only invited players can join. For testing, you can also set visible to false so it does not appear in the server browser at all.

Can Xbox and PlayStation players join my Arma Reforger server?

Yes, if you set game.crossPlatform to true and leave supportedPlatforms undefined. If you want a PC-only server, leave crossplay off or omitted and keep the default PC-only platform behaviour.

How do I add mods to an Arma Reforger dedicated server?

Add entries to the mods array with each mod’s GUID, name and, if you want stability, a pinned version. Required mods are automatically downloaded and activated by clients when they join, so add mods one at a time, watch the profile logs after each startup, and pin versions for anything important to avoid surprise changes after a mod update.

More Arma Reforger server help

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