Left 4 Dead 2

Left 4 Dead 2 is one of the most lightweight dedicated servers available. This guide covers installation, configuration, and deployment on Linux.

Left 4 Dead 2 has a small footprint and low resource requirements, making it ideal for budget VPS deployments. You can run multiple instances on a single small VPS.

• RAM: 1GB minimum (2GB recommended)
• vCPU: 2+ cores
• Storage: 15GB+ available space
• Network: Standard upstream bandwidth
• OS: Ubuntu 20.04+ or similar

Update your system and install dependencies:

sudo apt update && sudo apt upgrade -y
sudo apt install -y steamcmd lib32gcc-s1 lib32stdc++6 libncurses5:i386

Create a dedicated user:

sudo useradd -m -s /bin/bash steam
sudo su - steam
mkdir -p ~/steamcmd
cd ~/steamcmd
steamcmd +quit

Download the server using SteamCMD (AppID 222860):

cd ~/steamcmd
./steamcmd.sh +login your_steam_username your_steam_password +app_update 222860 validate +quit

The server installs to ~/steamcmd/steamapps/common/Left 4 Dead 2 Dedicated Server/.

Verify installation:

ls -la ~/steamcmd/steamapps/common/Left\ 4\ Dead\ 2\ Dedicated\ Server/

Create server.cfg in the left4dead2/cfg/ directory:

mkdir -p ~/steamcmd/steamapps/common/Left\ 4\ Dead\ 2\ Dedicated\ Server/left4dead2/cfg
nano ~/steamcmd/steamapps/common/Left\ 4\ Dead\ 2\ Dedicated\ Server/left4dead2/cfg/server.cfg

server.cfg:

Campaign and Difficulty Settings

Map names for coop:

Difficulty levels:

• c1m1_apartment — No Mercy
• c2m1_highway — Crash Course
• c3m1_plankcountry — Swamp Fever
• c4m1_milltown_a — Hard Rain
• c5m1_waterfront — The Parish
• 0 — Easy
• 1 — Normal
• 2 — Hard
• 3 — Impossible

Basic command:

cd ~/steamcmd/steamapps/common/Left\ 4\ Dead\ 2\ Dedicated\ Server
./srcds_run -game left4dead2 -console -usercon +sv_pure 2 +map c1m1_apartment +maxplayers 8 +ip 0.0.0.0 -port 27015

Launch parameters:

Custom Startup Script

Create start-l4d2.sh:

nano ~/start-l4d2.sh

#!/bin/bash
cd ~/steamcmd/steamapps/common/Left\ 4\ Dead\ 2\ Dedicated\ Server
./srcds_run -game left4dead2 \
  -console \
  -usercon \
  +sv_pure 2 \
  +map c1m1_apartment \
  +maxplayers 8 \
  +ip 0.0.0.0 \
  -port 27015 \
  +exec server.cfg

chmod +x ~/start-l4d2.sh
./start-l4d2.sh

• -game left4dead2 — Game type
• -console — Enable console
• -usercon — Allow user console commands
• +sv_pure 2 — Enforce pure server
• +map c1m1_apartment — Starting map
• +maxplayers 8 — Maximum players
• +ip 0.0.0.0 — Listen on all interfaces
• -port 27015 — Game port

Open required ports:

sudo ufw allow 27015/udp
sudo ufw allow 27015/tcp
sudo ufw allow 27020/udp

Port assignments:

• 27015/UDP+TCP — Game server port
• 27020/UDP — SourceTV port (optional, for spectators/demos)

Create /etc/systemd/system/l4d2-server.service:

sudo tee /etc/systemd/system/l4d2-server.service > /dev/null <<'EOF'
[Unit]
Description=Left 4 Dead 2 Dedicated Server
After=network-online.target
Wants=network-online.target

[Service]
Type=simple
User=steam
WorkingDirectory=/home/steam/steamapps/common/Left 4 Dead 2 Dedicated Server
ExecStart=/home/steam/steamapps/common/Left 4 Dead 2 Dedicated Server/srcds_run \
  -game left4dead2 \
  -console \
  -usercon \
  -port 27015 \
  +exec server.cfg
Restart=on-failure
RestartSec=10
StandardOutput=journal
StandardError=journal

[Install]
WantedBy=multi-user.target
EOF

Enable and start:

sudo systemctl daemon-reload
sudo systemctl enable l4d2-server
sudo systemctl start l4d2-server

Check status:

sudo systemctl status l4d2-server
sudo journalctl -u l4d2-server -f

Add Workshop Content

Download mods via SteamCMD:

./steamcmd.sh +login your_steam_username your_steam_password +workshop_download_item 550 addon_id +quit

Mods download to steamapps/workshop/content/550/.

Enable Addons

Copy addon files to the addons folder:

cp -r ~/steamcmd/steamapps/workshop/content/550/addon_id/* \
  ~/steamcmd/steamapps/common/Left\ 4\ Dead\ 2\ Dedicated\ Server/left4dead2/addons/

Addon types:

SourceTV (Spectator Mode)

Enable SourceTV in server.cfg:

• .vpk — Mod packages
• .bsp — Custom maps
• Extracted folders — Loose addons

Set the mutation mode in server.cfg:

Available mutations:

• mutation_1 — Tougher Than The Rest
• mutation_2 — Headshot! Headshot!
• mutation_3 — Bleed Out
• mutation_4 — Hard Eight
• mutation_5 — Versus Survival
• mutation_6 — Chainsaw Massacre
• mutation_7 — Versus Survival
• mutation_8 — Hunting Party

Backup Server Configuration

tar -czf l4d2-backup-$(date +%Y%m%d).tar.gz \
  ~/steamapps/common/Left\ 4\ Dead\ 2\ Dedicated\ Server/left4dead2/cfg/

Update Server

cd ~/steamcmd
./steamcmd.sh +login your_steam_username your_steam_password +app_update 222860 validate +quit
sudo systemctl restart l4d2-server

Monitor Performance

top
netstat -tupn | grep 27015
du -sh ~/steamcmd/steamapps/common/Left\ 4\ Dead\ 2\ Dedicated\ Server/

Server won't start: Run manually to see error messages

cd ~/steamcmd/steamapps/common/Left\ 4\ Dead\ 2\ Dedicated\ Server
./srcds_run -game left4dead2 -console

Players can't connect: Verify UDP port 27015 is open, test with nmap -uU your_ip -p 27015

Map won't load: Ensure map name is correct, check maps/ folder for availability

Addons causing crashes: Remove the addon and rebuild the list

rm ~/steamapps/common/Left\ 4\ Dead\ 2\ Dedicated\ Server/left4dead2/addons/*

High CPU usage: Reduce maxplayers or disable unnecessary convars

Run multiple L4D2 servers on different ports:

# Instance 1
./srcds_run -game left4dead2 -console -port 27015 +exec server1.cfg &

# Instance 2
./srcds_run -game left4dead2 -console -port 27016 +exec server2.cfg &

Open both ports in your firewall.

Step 1: Download Server on Windows

steamcmd +force_install_dir "C:\L4D2-Server" +login your_steam_username your_steam_password +app_update 222860 validate +quit

Step 2: Create server.cfg

Create C:\L4D2-Server\left4dead2\cfg\server.cfg (same as Linux guide in Configuration File section).

Step 3: Create Startup Batch

Create C:\L4D2-Server\start-server.bat:

@echo off
cd /d C:\L4D2-Server
srcds.exe -game left4dead2 -console -usercon +sv_pure 2 +map c1m1_apartment +maxplayers 8 +ip 0.0.0.0 -port 27015
pause

Step 4: Run as Service (Optional)

nssm install L4D2Server "C:\L4D2-Server\srcds.exe" "-game left4dead2 -console -port 27015 +exec server.cfg"
nssm start L4D2Server

sv_allow_lobby_connect_only Parameter

Recommendation: Use 0 for public servers, 1 for competitive/closed groups.

Server.cfg Rate Settings

Sourcemod + L4DToolZ for Increased Slots

Extend server capacity beyond default 8 slots:

Installation:

Enable higher slots in server.cfg:

RCON Admin Commands

Access console via RCON:

telnet your_server_ip 27015
# Enter rcon_password when prompted

• Download Sourcemod for Left 4 Dead 2
• Extract to left4dead2/addons/
• Download L4DToolZ plugin
• Place in left4dead2/addons/sourcemod/plugins/

• Install Sourcemod for advanced admin control
• Configure L4DToolZ for increased player slots
• Set up competitive mod settings if desired
• Create custom campaign rotations
• Monitor server stability on high player counts