How to install mods on your Arma 3 server

Arma 3 mods are folders whose names start with an @ symbol. The server needs the folder, the launch parameter and the signature key.

1. Get the mod files

1. Subscribe to the mod in the Steam Workshop on your own PC and let it download.
2. In the Arma 3 Launcher, open the mod's context menu and choose the option to open its folder.
3. The folder you want is the one containing addons and a keys folder.

2. Upload to the server

1. Stop the server.
2. In the Files tab, upload the mod folder to the server root and name it @ModName. Use SFTP for anything large, since mods are often several gigabytes.
3. Repeat for each mod.

3. Load them at startup

Mods are loaded by a launch parameter, so this is set on the Startup page of your server. That page is not linked in the sidebar, so open your server in the panel and add /startup to the end of the address. The value is a list separated by semicolons:

-mod=@CBA_A3;@ace;@MyMap

Server side only mods go in -serverMod= instead, so clients are not asked for them.

4. Install the signature keys

1. Open each mod folder and find its keys folder with a .bikey file inside.
2. Copy every .bikey file into the keys folder in your server root.
3. Leave verifySignatures = 2; in server.cfg.

Without the key, players running that mod are kicked with a signature error even though the mod is correct.

5. Match your players

• Everyone loads the same mods in the launcher. Export your list as a preset and share the file.
• Mod versions must match. After a Workshop update, everyone updates, including the server.
• Start the server and read the console. Each loaded mod is listed during boot, which is how you confirm the parameter is right.

Add mods a few at a time. If the server stops booting after a batch, remove the last one you added and start again.