Arma 3 Headless Client Setup Guide
Headless clients (HCs) offload AI computation to a separate process, freeing your server's
main thread for players. Fill in your details below to generate the exact
server.cfg additions and HC launch command you need.
Server Configuration
The IP players (and HCs) use to connect.
HC must supply the same password to connect.
Arma 3 supports a maximum of 3 HCs simultaneously.
Common Gotchas
allowedFilePatching = 1; is required
Setting this to 0 (the default) blocks headless clients entirely.
They cannot connect at all without this. Set it to 1 (allow selected clients)
or 2 (allow all) in your server.cfg.
HC counts toward maxPlayers
Each headless client occupies one player slot. If you have 40-player slots and 2 HCs,
only 38 real players can join. Raise maxPlayers to compensate.
Maximum 3 HCs simultaneously
Arma 3 only recognizes up to 3 headless clients at a time. Additional HC connections beyond 3 are treated as regular players.
Mission must have HC support scripted in
HCs don't automatically take over AI. Your mission must include a framework that transfers AI groups to the HC — the most popular option is Werthles' Headless Kit. Without this, HCs connect but do nothing useful.
server.cfg Additions
Add these lines to your existing server.cfg
// Headless Client settings
headlessClients[] = { "HC_IP_1" };
localClient[] = { "HC_IP_1" };
allowedFilePatching = 1;
Replace each HC_IP_x placeholder with the actual IP of that HC machine.
HC Launch Command
Windows — run each as a separate process or batch file
rem === Headless Client 1 === arma3server.exe -client -connect=SERVER_IP -profiles=HC_Profiles_1 -nosound -world=empty
Save each command as a separate .bat file (e.g. start-hc1.bat) and run it from your Arma 3 server directory.
Step-by-Step Setup Checklist
- 1
Add the
server.cfglines above to your server configPaste the generated block into your existing
server.cfg, outside any existing arrays. - 2
Raise
maxPlayersby 1Each HC occupies one slot. If your intended player cap is 40, set
maxPlayers = 41;to keep 40 real slots open. - 3
Restart the Arma 3 server
The
server.cfgchanges are only picked up on a full server restart — not a mission change. - 4
Launch your HC using the command above
Run each command from the Arma 3 server installation directory. The HC process has no visible window — check the
HC_Profilesfolder for logs. - 5
Verify the HC appears in the server player list
A connected HC appears as a player named
Headless(or the profile name you set). It is invisible to other players in-game but visible in RCON and admin tools. - 6
Load a mission with HC support scripted in
Without a framework like Werthles' Headless Kit embedded in the mission, the HC will be connected but idle. No AI groups will be transferred to it automatically.
- 7
Confirm AI transfer in RPT logs
Check
arma3server_YYYY-MM-DD_HH-MM-SS.rptfor HC framework messages confirming group transfers. The HC's own log will show the groups it has taken ownership of.
server.cfg Parameter Reference
| Parameter | Values | Purpose |
|---|---|---|
| headlessClients[] | Array of IP strings | IPs allowed to connect as a headless client. Only these addresses receive HC privileges. |
| localClient[] | Array of IP strings | IPs that bypass bandwidth throttling. Should match headlessClients[] to ensure HCs receive data at full speed. |
| allowedFilePatching | 0, 1, 2 | Required for HCs. 0 = blocked (default), 1 = headlessClients[] only, 2 = all clients. Must be 1 or 2 or HCs cannot connect. |
| maxPlayers | Integer | Total slot count including HCs. Increase by the number of HCs you run to preserve player slot count. |
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