Killing Floor server

Run a Killing Floor dedicated server with LinuxGSM, in Docker or directly on Linux.

kfserver Docker kfUnreal 2

Steam login required. This server cannot be downloaded anonymously, so LinuxGSM needs a Steam username and password. Use a dedicated Steam account.

Run with Docker

First install Docker Engine and the Compose plugin on your Linux host. Run the commands below from your project directory with a user allowed to access Docker; otherwise prefix Docker commands with sudo. The container manages its own linuxgsm user.

The kf image has LinuxGSM and every dependency for Killing Floor already installed on Ubuntu 26.04. On first start it downloads the game server, then keeps it updated.

1. Create `compose.yaml`

compose.yaml

services:
  kfserver:
    image: ghcr.io/gameservermanagers/gameserver:kf
    container_name: kfserver
    restart: unless-stopped
    network_mode: host
    volumes:
      - ./kfserver:/data
    environment:
      - UPDATE_CHECK=60

Also published on Docker Hub as gameservermanagers/gameserver:kf. Prefer docker run? See Docker help.

2. Add your Steam login before the first start

Create the LinuxGSM config file inside the data directory. LinuxGSM reads it on first start and keeps it on updates.

shell

mkdir -p kfserver/config-lgsm/kfserver
nano kfserver/config-lgsm/kfserver/common.cfg

common.cfg

steamuser="username"
steampass='password'

3. Start it

shell

docker compose up -d
docker compose logs -f

The first start installs the server, which can take a while for large games. When it is ready the log shows the server details, including ports and passwords.

Ports

With network_mode: host the server uses the host's ports directly, so there is nothing to map. Open them in your firewall.

Ports for this game are set in its own config file. Run details to see every port and its protocol.

Manage the server

Show details, ports and passwords

docker exec -it --user linuxgsm kfserver ./kfserver details

Open the live console (leave with CTRL+b then d)

docker exec -it --user linuxgsm kfserver ./kfserver console

Restart the game server

docker restart kfserver

Check for a game update now

docker exec -it --user linuxgsm kfserver ./kfserver update

Update the image

docker compose pull && docker compose up -d

Server files, configs and logs live in ./kfserver on the host: back up that directory. Docker help below covers permissions, environment variables and bridge networking.

Docker help

Images and tags

Images are built weekly and published to two registries. They are identical, so use whichever you prefer.

Registry	Image
GitHub Container Registry	`ghcr.io/gameservermanagers/gameserver:kf`
Docker Hub	`gameservermanagers/gameserver:kf`

The image uses the base OS LinuxGSM recommends for this game. You do not need to match it on the host.

Use docker run instead of Compose

shell

docker run -d \
  --name kfserver \
  --network host \
  --restart unless-stopped \
  -v "$PWD/kfserver:/data" \
  -e UPDATE_CHECK=60 \
  ghcr.io/gameservermanagers/gameserver:kf

Data and permissions

Everything that should survive a container update lives in /data inside the container, which is ./kfserver on the host.

Path in `/data`	Contents
`serverfiles/`	The game server itself
`config-lgsm/`	LinuxGSM config, including `common.cfg`
`log/`	Script, console and game logs
`data/`	LinuxGSM data and cache

The game server runs as the linuxgsm user, not root. On every start the container sets that user to UID and GID (both 1000 by default) and takes ownership of /data. If your host user has a different ID, set them to match so you can edit files on the host:

compose.yaml

environment:
      - UID=1001
      - GID=1001

Environment variables

Variable	Default	What it does
`UPDATE_CHECK`	`60`	Minutes between update checks, from `1` to `59`, or `60` for hourly. `0` turns scheduled checks off.
`UPDATE_ON_START`	`true`	Check for a game update every time the container starts.
`VALIDATE_ON_START`	`false`	Run a SteamCMD validate on start. Slow, but repairs broken files.
`UID` / `GID`	`1000`	User and group IDs the game server runs as.
`LGSM_GITHUBBRANCH`	`master`	LinuxGSM branch to run. Set `develop` to test unreleased fixes.

Updates and health checks

The game server updates itself. The container checks every UPDATE_CHECK minutes and on start. If an update is out, it stops the server, updates it and starts it again.

The image brings new LinuxGSM releases, dependency fixes and OS updates. Pull it now and then with docker compose pull && docker compose up -d.

The image runs LinuxGSM's monitor as the Docker health check every minute, so docker ps shows whether the game server is answering, not just whether the container is up.

Bridge networking

network_mode: host is the simplest choice: the game server uses the host's ports directly, the way it would without Docker, and query ports work without extra setup.

If you need bridge networking, publish each port the server uses. Run details to see them, then add them with the right protocol:

compose.yaml

ports:
      - "PORT:PORT/udp"
      - "PORT:PORT/tcp"

Bridge networking can hide the server's real IP from the game, which breaks some server browsers. Use host networking if players cannot find the server.

Troubleshooting

Permission denied in /data: set UID and GID to the owner of the host directory.
Server not listed in game: check the ports are open, use host networking, and add a GSLT if the game needs one.
Install fails at SteamCMD: the game may need a Steam login. Check the notes at the top of this page.
Will not start: stop the container, then run docker compose run --rm kfserver debug to see why.
Still stuck: run details and debug, then ask on Discord or GitHub Discussions with the output.

Install on Linux

Install directly on a server running Ubuntu 26.04, Debian 11 or Enterprise Linux 8.

1. Create a user and log in

Creating users and installing system packages require administrator privileges. From your administrator account, use sudo below (omit it if already root). Install curl, tar and an editor such as nano with your distribution's package manager first.

administrator shell

sudo adduser kfserver

Give the user a strong password, then switch to its login shell:

administrator shell

sudo su - kfserver

Run all remaining commands as kfserver from its home directory, without sudo. On Enterprise Linux, create the account with sudo useradd -m kfserver and set its password with sudo passwd kfserver instead of adduser.

2. Download LinuxGSM

shell

curl -Lo linuxgsm.sh https://linuxgsm.sh && chmod +x linuxgsm.sh && bash linuxgsm.sh kfserver

3. Add your Steam login

Create lgsm/config-lgsm/kfserver/common.cfg relative to the game-server user's home directory and add your dedicated Steam account:

shell

mkdir -p lgsm/config-lgsm/kfserver
nano lgsm/config-lgsm/kfserver/common.cfg

common.cfg

steamuser="username"
steampass='password'

4. Install

shell

./kfserver install

LinuxGSM checks dependencies and installs the game files. If this user has sudo access, it can install missing packages when prompted. Otherwise, ask an administrator to install the packages listed by LinuxGSM, then rerun this command as kfserver. Running ./kfserver install as root only installs dependencies, not the game server.

5. Configure and start the server

Review your LinuxGSM settings in lgsm/config-lgsm/kfserver/kfserver.cfg (instance settings) or lgsm/config-lgsm/kfserver/common.cfg (shared settings). Do not edit _default.cfg, which LinuxGSM updates automatically. Game settings use a separate config file; run ./kfserver details to find its path. Once configured, start the server explicitly:

shell

./kfserver start

Common commands

Start the server

start

./kfserver start

Stop the server

stop

./kfserver stop

Restart the server

restart

./kfserver restart

Show details, ports and passwords

./kfserver details

Open the live console (leave with CTRL+b then d; CTRL+c stops the server)

./kfserver console

Update the game server

./kfserver update

Run in the foreground to debug

./kfserver debug

Back up the whole server

./kfserver backup

List every command

./kfserver

Automate with cron

Restart the server if it crashes, apply game updates and keep LinuxGSM current. Add these with crontab -e.

crontab

*/5 * * * * /home/kfserver/kfserver monitor > /dev/null 2>&1
*/30 * * * * /home/kfserver/kfserver update > /dev/null 2>&1
0 0 * * 0 /home/kfserver/kfserver update-lgsm > /dev/null 2>&1

Killing Floor server

Run with Docker

1. Create compose.yaml

2. Add your Steam login before the first start

3. Start it

Ports

Manage the server

Docker help

Install on Linux

1. Create a user and log in

2. Download LinuxGSM

3. Add your Steam login

4. Install

5. Configure and start the server

Common commands

Automate with cron

1. Create `compose.yaml`