Arma 3 Server Hosting

What is an Arma 3 dedicated server and what game types can it host?

The Arma 3 dedicated server is the official server application Bohemia Interactive publishes for its military simulation game, running missions independently of players. Arma 3’s strength is that game modes are defined almost entirely by mission files and mods; the same server software can host anything from a one-evening co-op mission to a campaign lasting months.

Common server types in Arma communities:

• Milsim (military simulation) units: Planned operations, rank structures and realistic play with ACE and radio mods.
• Co-op mission servers: Missions against AI, run by the community or a Zeus game master.
• Persistent scenarios: Long-running campaigns such as Antistasi, where progress is saved between sessions.
• PvP scenarios: Large-scale player battles such as King of the Hill.

The game type directly determines the server’s resource needs: a co-op mission running hundreds of AI units needs far more CPU than a PvP scenario with the same number of players.

A unit that runs its own server sets its own operation schedule, mod list and mission files. Opening the server with a password only at set hours for weekly operations, and loading a separate mission on training days, gives you a structure that shared servers cannot. In Zeus-run missions, the game master’s live interventions also consume server resources, so it is wise to plan resources a little generously for live-managed operations.

How many resources does an Arma 3 server need?

On an Arma 3 server the decisive resource is the CPU: mission logic and AI calculations run largely on a single thread, so high single-core performance matters even more than player count. The values in the table are estimates; the number of AI in the mission and the mod list change the requirement.

Factors to consider when planning resources:

• AI units: Every soldier, vehicle and group active at the same time loads the server CPU. Falling server FPS, unresponsive AI and desync are the symptoms.
• Mod list: Large mods such as ACE, CBA_A3, RHS or CUP significantly increase memory and disk use. Large mod sets can take up tens of GB of disk space.
• Mission scripts: Poorly written mission scripts or ones running constant loops slow the server down regardless of hardware.
• Headless client: Spreads AI calculations across separate processes and lightens the main server’s load; these processes need extra cores and memory as well.

Dedicated cores remove the fluctuations caused by neighbouring workloads in a CPU-sensitive game like Arma 3. Plan disk space generously for large mod sets; NVMe storage noticeably shortens mod loading time at start-up.

Game package or VDS for Arma 3?

At LIONFIN you run an Arma 3 server on a VDS; this page lists VDS plans for the game. You can install the server yourself or open a support ticket from the customer panel after ordering the VDS and ask for the setup.

Arma 3 servers need active management, with mods and mission files changing often. A VDS fits this in several ways:

• Full file access: You manage the mod folders, the keys folder and the mpmissions directory directly.
• Headless client: You can run one or more headless client processes on the same machine as the main server.
• Multiple instances: Run separate server instances for different mod sets (for example a milsim server and a training server).
• Choice of operating system: Windows Server or Linux; both are officially supported.

According to the official Arma 3 documentation, the server needs a native IPv4 connection; IPv6 or IPv4 over an IPv6 tunnel (DS-Lite) is not supported. VDS plans come with a public IPv4 address. A general comparison of a game package and a VDS is on the game server package vs VDS page; current plan values are shown in the plan table on this page.

Windows or Linux? How do you install the server?

The Arma 3 dedicated server is released for both Windows and Linux. The Windows version offers the widest mod compatibility and most community tools are built for Windows; the Linux version needs no licence and uses resources more efficiently, but some mods and server add-ons can cause problems on Linux.

The basic installation workflow:

1. Create a separate user to run the server; the official documentation recommends running SteamCMD as a separate user rather than root.
2. Download the files with SteamCMD:

   steamcmd +force_install_dir /home/arma3/server +login anonymous +app_update 233780 validate +quit

   According to Valve’s server list the server package can be downloaded anonymously; if you get a login error, sign in with a Steam account.
3. Create the server.cfg and basic.cfg files.
4. Start the server; the 64-bit binary is arma3server_x64 on Linux and arma3server_x64.exe on Windows:

   ./arma3server_x64 -port=2302 -config=server.cfg -cfg=basic.cfg -profiles=profile -name=server "-mod=@cba_a3;@ace"

On Linux, mod folder and file names must be lowercase; mod folders with uppercase letters may not load.

What do you configure in server.cfg and basic.cfg?

An Arma 3 server’s identity, security and mission cycle are kept in server.cfg, and network bandwidth settings in basic.cfg. Difficulty settings live separately in the server profile’s .Arma3Profile file.

hostname = "LIONFIN Milsim EU";
password = "";
passwordAdmin = "a-long-and-unique-password";
serverCommandPassword = "another-password";
maxPlayers = 60;
verifySignatures = 2;
kickDuplicate = 1;
persistent = 1;
BattlEye = 1;

• passwordAdmin: Used to become admin in-game with the #login command.
• verifySignatures = 2: Lets players connect only with signed mod files whose keys are on the server.
• persistent = 1: Keeps the mission running when the last player leaves; important for persistent scenarios.
• BattlEye: Enables anti-cheat.

The class Missions block in server.cfg decides which mission the server starts automatically and at what difficulty. basic.cfg settings control the amount and size of packets the server sends; the defaults suit most servers, but on busy servers fine-tuning can improve synchronisation. Copy the files before making changes.

Difficulty settings (AI accuracy, third-person camera, map markers, crosshair and so on) are defined in the CustomDifficulty section of the server profile and selected in the mission cycle with difficulty = "Custom";. Milsim units usually disable the third-person camera and crosshair and keep AI skill at a medium level. Remember that these settings are enforced server-side and override the player’s own settings.

How do you manage mods and .bikey keys?

To add mods to an Arma 3 server, copy the mod folders into the server directory and add them to the -mod= parameter on the launch line; also place each mod’s .bikey key in the server’s keys folder. With verifySignatures = 2 enabled, the server requires players’ mods to be signed with these keys.

1. Download the mods: You can download Workshop mods with SteamCMD; this requires logging in with a Steam account that owns Arma 3 (the game’s client ID is 107410):

   steamcmd +login USERNAME +workshop_download_item 107410 MOD_ID +quit

2. Place the folders: Copy the mods into the server directory as @modname; on Linux convert the names to lowercase.
3. Copy the keys: Put the .bikey file from each mod’s keys or key folder into the server’s keys folder.
4. Update the launch line: Mods that players must also load go in -mod=; mods that run only on the server go in -serverMod=.

Players need the same mod list as the server. Communities prepare a shareable mod list (preset) in the Arma 3 Launcher or use a Workshop collection for this. When updating mods, update the server and the keys at the same time; an old key causes players connecting with the new mod version to be kicked.

What is a headless client and when do you need one?

A headless client (HC) in Arma 3 is a separate client process that renders nothing, connects to the server like a player and takes over AI calculations from the main server. Because the AI load in Arma 3 piles onto a single core of the main server, using an HC in large co-op missions noticeably improves server FPS and AI responsiveness.

An HC helps when:

• A mission has hundreds of AI units active at the same time,
• A large part of the map is active in a persistent scenario such as Antistasi,
• Server FPS drops noticeably at busy moments.

The HC starts from the same files as the main server and connects to it:

./arma3server_x64 -client -connect=127.0.0.1 -port=2302 -password=SERVER_PASSWORD "-mod=@cba_a3;@ace"

The mission file must support HCs, and the address the HC connects from must be allowed in server.cfg. Each HC process uses its own core and memory, so if you are planning HCs, choose resources from the upper ranges in the table. Running the HC on the same VDS gives a local connection with no network delay.

Each HC process must have exactly the same mod list as the main server; a different mod set stops the HC connecting or makes the AI misbehave. Starting the server and HC processes from the same script is an easy way to keep them in sync.

Which ports need to be open?

An Arma 3 server uses the base port set with the -port parameter (default 2302) and several ports after it; on a default install you need to open the 2302–2306/UDP range.

sudo ufw allow 2302:2306/udp

If you run a second Arma 3 server on the same VDS, offset the base port by at least five to ten (for example 2312), otherwise the port ranges overlap. The official documentation also states that the base port must be changed for multiple instances.

How do you monitor and improve server performance?

The key indicator of an Arma 3 server’s health is server FPS; after logging in as admin, the #monitor command shows the server’s FPS and bandwidth values at regular intervals. As server FPS drops, AI becomes unresponsive and vehicles and units lose synchronisation.

Practices that improve performance:

• AI management: Use mission scripts or mods that freeze or cache units far from players.
• Headless client: Offload AI to an HC.
• View distance: Keep server- and mission-side view distance reasonable; very long distances increase calculation load.
• Wreck and body cleanup: Enable garbage collector settings in missions; piles of destroyed vehicles and bodies slow the server down.
• Trim the mods: Remove mods you do not use.

To monitor CPU and memory use at the operating-system level, standard tools such as htop are enough. If the delay players experience comes from the network rather than server FPS, compare ping with the #monitor output at the time of the problem.

How do you back up mission files and persistent progress?

What needs backing up on an Arma 3 server: the mission files in mpmissions, server.cfg and basic.cfg, the server profile folder and the keys folder. Persistent scenarios (such as Antistasi) mostly store progress in the variables file in the server profile (.vars.Arma3Profile); if that file is lost, campaign progress is lost with it.

• Profile folder: Archive the folder set with the -profiles parameter every day.
• Missions and configuration: Include mpmissions, the configuration files and the keys folder in the backup.
• Mods: Workshop mods can be downloaded again, but back up any mods you edited by hand or your own custom mods separately.
• Off-site copy: Move the archives to another location.

Persistent scenarios usually write their saves from within the mission or when the server shuts down cleanly; abrupt shutdowns can lose the latest progress.

How is an Arma 3 server protected against DDoS and cheating?

Arma 3 server security relies on BattlEye anti-cheat, signature verification, strong admin passwords and network-level DDoS filtering used together. On LIONFIN infrastructure the RouteFence firewall filters at the network level and traffic is monitored 24/7 by our NOC and SOC teams; see our data center for more.

• BattlEye: Keep it enabled in server.cfg; BattlEye filter files let you write rules that fit your mission and mods.
• Signature verification: Use verifySignatures = 2 to block connections with modified mod files.
• Admin passwords: Keep passwordAdmin and serverCommandPassword different and strong.
• Mission security: Review mission scripts that allow remote code execution and your CfgRemoteExec settings.

The most common problem on public Arma 3 servers is abuse of remote script execution. Allowing only the functions that genuinely need it to be called remotely in your mission files, and tuning BattlEye filters to your mission, blocks most of these attacks. If you run a closed unit server, putting a password on it and sharing that only with members is the simplest and most effective protection.

What are the most common Arma 3 server errors?

Most Arma 3 server problems come from mod signatures, port conflicts and mission file errors.

The first place to look when the server has problems is the .rpt log file in the profile folder. If you cannot solve it, open a support ticket from the customer panel; attaching the relevant part of the log and your mod list speeds up diagnosis.