ARMA 3 – Installing and Managing Mods

This guide shows you step by step how to install and manage mods on your ARMA 3 server. ARMA 3 has a huge modding community – from new weapons to vehicles to complete gameplay overhauls like ACE or TFAR.

How Do ARMA 3 Mods Work?

ARMA 3 mods are downloaded via the Steam Workshop. Each mod has its own folder that starts with @ (e.g. @cba_a3, @ace). The server loads the mods on startup and all players must have exactly the same mods installed.

Step 1: Download Mods

Method A: Via SteamCMD (recommended for servers)

# Start SteamCMD
cd ~/steamcmd
./steamcmd.sh

# Log in
login YOUR_STEAM_USERNAME

# Installation directory
force_install_dir ~/arma3-mods

# Download mod by Workshop ID
workshop_download_item 107410 463939057

# Workshop ID explained:
# 107410 = ARMA 3 App ID
# 463939057 = Mod ID (from the Workshop URL)

You can find the Workshop ID in the mod's URL:

https://steamcommunity.com/sharedfiles/filedetails/?id=463939057
                                               ^^^^^^^^^
                                               Mod ID

Method B: Manual Copy from Workshop

If you have ARMA 3 installed on the same machine:

1. Subscribe to the mods in the Steam Workshop
2. Navigate to the Workshop folder:

   C:\Program Files (x86)\Steam\steamapps\workshop\content\107410\

3. Each folder inside is a mod (named after the Mod ID)
4. Copy the desired folders to your server

Step 2: Set Up Mods in the Server Folder

# Create and rename mod folders
mkdir ~/arma3/@cba_a3
mkdir ~/arma3/@ace
mkdir ~/arma3/@rhsafrf

# Copy Workshop files into the @ folders
cp -r ~/arma3-mods/steamapps/workshop/content/107410/463939057/* ~/arma3/@cba_a3/
cp -r ~/arma3-mods/steamapps/workshop/content/107410/463939058/* ~/arma3/@ace/

Important: The folder name MUST start with @. Otherwise ARMA 3 won't recognize the mod.

Step 3: Install Mod Keys

Each mod has a .bikey key that must be placed in the server's keys/ folder:

# Create keys folder (if it doesn't exist)
mkdir ~/arma3/keys

# Copy keys from all mods
cp ~/arma3/@cba_a3/keys/*.bikey ~/arma3/keys/
cp ~/arma3/@ace/keys/*.bikey ~/arma3/keys/
cp ~/arma3/@rhsafrf/keys/*.bikey ~/arma3/keys/

Without the correct key, players cannot join when verifySignatures = 2 is set.

Step 4: Adjust Server Startup Parameters

Add the mods to your startup script:

Windows (start.bat)

arma3server_x64.exe -port=2302 -config=server.cfg -cfg=basic.cfg -name=server -mod=@cba_a3;@ace;@rhsafrf;@tfar -autoInit

Linux

./arma3server -port=2302 -config=server.cfg -cfg=basic.cfg -name=server -mod=@cba_a3\;@ace\;@rhsafrf\;@tfar

Important:

• Windows: Separate mods with semicolon ;
• Linux: Separate mods with semicolon, but escape the semicolon with backslash: \;
• Pay attention to order: Basic mods first (CBA), then those that build on them (ACE, RHS, TFAR)

Step 5: Configure server.cfg for Mods

// Check mod signatures
verifySignatures = 2;    // 0 = off, 1 = warn, 2 = strict (recommended)

// Mod requirement for players
equalModRequired = 1;    // 0 = players can join with fewer mods
                         // 1 = players need exactly the same mods

The Most Important ARMA 3 Mods

Keeping Mods Up to Date

# Update all mods via SteamCMD
cd ~/steamcmd
./steamcmd.sh

login YOUR_STEAM_USERNAME
force_install_dir ~/arma3-mods

# Update each mod individually
workshop_download_item 107410 450814997 validate
workshop_download_item 107410 463939057 validate
workshop_download_item 107410 894678801 validate

quit

Using validate detects corrupted files and re-downloads them.

Optimizing Mod Load Order

The order is crucial. Wrong order = crashes or faulty mods:

1. CBA_A3 – ALWAYS first
2. Basic mods: ace, ace_compat
3. Large content mods: RHS, CUP (in any order)
4. Function mods: TFAR, ACRE2
5. Small addons: Maps, weapons, vehicles from individual creators

Common Problems

Players cannot join – "Mod signature mismatch":

• Player has a different mod version than the server
• Player hasn't installed all mods
• Player has additional mods that the server doesn't have
• Solution: Give all players the same mod list

Server won't start after mod installation:

• Check mod order – CBA must be before ACE, ACE before RHS
• Are keys missing from the keys/ folder?
• Are mod folders correctly named with @?

Mods load extremely slowly:

• ARMA 3 loads mods into RAM on startup – large mods like RHS need several GB
• Use SSD instead of HDD
• Deactivate unnecessary mods

Quick Checklist

1. Mods downloaded via SteamCMD or Workshop
2. Mod folders named with @
3. Keys copied to the keys/ folder
4. Startup parameters extended with -mod=
5. Mod load order checked (CBA first)
6. verifySignatures set in server.cfg
7. Server started and checked for errors