Dedicated server guide

Left 4 Dead 2

Manage l4d2server with AlphaGSM. Choose a runtime supported by the recorded module capabilities.

Recorded lifecycle pass · Support evidence: 2026-10-16.

Anonymous Workshop Process and Docker load passed for public dedicated-server content. Mod installation explains add, apply, and cleanup.

Build setup commands

Runtime familysteamcmd-linux

Declared runtimes: Docker or a Linux host process.

Network bindings

27015/UDP, 27015/TCP, clientport/UDP. Named port values remain unknown; review the game guide and configuration for additional requirements.

Mods and plugins

Declared curated families: metamod, sourcemod. The optional sourcemod example installs its dependencies and applies the mod plan before launch. For Workshop content, use the setup builder with an actual game-compatible item ID; review supported content types in the guide. Anonymous Steam Workshop content for this module passed both process and Docker load. After setup, record an item with mod add workshop using a numeric ID or Steam Workshop URL, then run mod apply.

Backup hook

A module-specific backup hook is declared. Review the game guide for its scope, restore procedure and shutdown requirements.

Choose a supported runtime

Linux and Docker quickstart

Review the game guide for installation, account, licensing and runtime prerequisites before setup.

Docker

Complete interactive setup and review game-specific configuration before starting the server. Review the game guide for installation, account, licensing and runtime prerequisites before setup. Optional curated example: sourcemod. Omit all optional mod steps for a base server.

Start the Docker manager ./alphagsm-docker start
Create the game instance ./alphagsm-docker my-l4d2server create l4d2server
Complete interactive setup ./alphagsm-docker my-l4d2server setup
Optional: add metamod # Optional curated mod: sourcemod; add metamod ./alphagsm-docker my-l4d2server mod add manifest metamod
Optional: add sourcemod # Optional curated mod: sourcemod; add sourcemod ./alphagsm-docker my-l4d2server mod add manifest sourcemod
Optional: apply the mod plan # Optional: apply the mod plan ./alphagsm-docker my-l4d2server mod apply
Start the game server ./alphagsm-docker my-l4d2server start
Check the instance status ./alphagsm-docker my-l4d2server status

./alphagsm-docker start
./alphagsm-docker my-l4d2server create l4d2server
./alphagsm-docker my-l4d2server setup
# Optional curated mod: sourcemod; add metamod
./alphagsm-docker my-l4d2server mod add manifest metamod
# Optional curated mod: sourcemod; add sourcemod
./alphagsm-docker my-l4d2server mod add manifest sourcemod
# Optional: apply the mod plan
./alphagsm-docker my-l4d2server mod apply
./alphagsm-docker my-l4d2server start
./alphagsm-docker my-l4d2server status

Host process

Create the game instance ./alphagsm my-l4d2server create l4d2server
Complete interactive setup ./alphagsm my-l4d2server setup
Optional: add metamod # Optional curated mod: sourcemod; add metamod ./alphagsm my-l4d2server mod add manifest metamod
Optional: add sourcemod # Optional curated mod: sourcemod; add sourcemod ./alphagsm my-l4d2server mod add manifest sourcemod
Optional: apply the mod plan # Optional: apply the mod plan ./alphagsm my-l4d2server mod apply
Check the host prerequisites ./alphagsm my-l4d2server doctor
Start the game server ./alphagsm my-l4d2server start
Check the instance status ./alphagsm my-l4d2server status

./alphagsm my-l4d2server create l4d2server
./alphagsm my-l4d2server setup
# Optional curated mod: sourcemod; add metamod
./alphagsm my-l4d2server mod add manifest metamod
# Optional curated mod: sourcemod; add sourcemod
./alphagsm my-l4d2server mod add manifest sourcemod
# Optional: apply the mod plan
./alphagsm my-l4d2server mod apply
./alphagsm my-l4d2server doctor
./alphagsm my-l4d2server start
./alphagsm my-l4d2server status

This guide covers the l4d2server module in AlphaGSM.

Requirements

screen
SteamCMD runtime libraries (lib32gcc-s1, lib32stdc++6)
Python packages from requirements.txt

Support Status

l4d2server is fully supported. AlphaGSM now installs app 222860 anonymously by staging the Windows depots first and then applying the Linux depots into the same server tree, which matches the current working SteamCMD install path for Left 4 Dead 2 Dedicated Server.

Quick Start

Create the server:

alphagsm myl4d2serv create l4d2server

Run setup:

alphagsm myl4d2serv setup

Start it:

alphagsm myl4d2serv start

Check it:

alphagsm myl4d2serv status

Stop it:

alphagsm myl4d2serv stop

Setup Details

Setup configures:

the game port (default 27015)
the install directory
the executable name
SteamCMD downloads the server files
default configuration and backup settings

setup now uses the proven two-phase anonymous SteamCMD install flow for app 222860: Windows depots first, then Linux depots in the same directory. This works around the current SteamCMD Invalid platform failure for a Linux-only anonymous install.

Useful Commands

alphagsm myl4d2serv update
alphagsm myl4d2serv backup

Notes

Module name: l4d2server
Default port: 27015

Server variables

After create l4d2server, inspect or change these with set:

alphagsm myserver set --list
alphagsm myserver set KEY --describe
alphagsm myserver set KEY VALUE

Key	Aliases	Type	What it does
`map`	gamemap, startmap, level, worldname	string	The currently selected map or level. Example: `c5m1_waterfront`.
`maxplayers`	users	integer	Maximum number of player slots. Example: `8`.
`port`	gameport	integer	The primary game port. Example: `27015`.
`rconpassword`	rconpass, querypassword, query_administrator_password	string	Remote console password for administrative access. Stored as a secret.
`servername`	hostname, name	string	The server's public name shown to players. Example: `AlphaGSM Left 4 Dead 2`.
`serverpassword`	sv_password, password	string	Password required for players to join the server. Stored as a secret.

Developer Notes

Run File

Executable: srcds_run
Location: <install_dir>/srcds_run
Engine: Source
SteamCMD App ID: 222860

Server Configuration

Config file: left4dead2/cfg/server.cfg
Key settings:
- hostname — Server name
- sv_maxrate — Max network rate
- rcon_password — Remote console password
Default port: 27015
Default map: c5m1_waterfront
Max players: 8
Ports:
- Game port: 27015 (UDP)
- Client port: 27005 (UDP)
Template: See server-templates/l4d2server/

Maps and Mods

Map directory: left4dead2/maps/
Mod directory: left4dead2/addons/
Workshop support: Anonymous item and collection downloads with game AppID validation and one bare VPK per item, including verified legacy upload names. The opt-in live test uses public Back To School and Admin System fixtures.
Mod notes: AlphaGSM manages addons from checked-in manifest entries, direct url entries, GameBanana IDs, Mod DB URLs, and game-validated Workshop IDs/collections. The manifest includes MetaMod and SourceMod. Direct URLs accept .vpk files or supported archives; GameBanana, Mod DB, and manifest sources install supported archives. Workshop items must contain one bare .vpk. mod cleanup removes AlphaGSM-tracked files and keeps its local cache/state under .alphagsm/mods/left4dead2/.
Current status: Fully supported. The current anonymous SteamCMD lane for app 222860 works when AlphaGSM stages the Windows depots first and then the Linux depots into the same install tree.
Map install: Copy .bsp files into left4dead2/maps/ and add to left4dead2/cfg/mapcycle.txt.
Mod install: Copy addon folders into left4dead2/addons/.

Examples:

alphagsm myl4d2 mod add manifest metamod
alphagsm myl4d2 mod add manifest sourcemod
alphagsm myl4d2 mod add url https://mods.example.invalid/custom-campaign.vpk
alphagsm myl4d2 mod add gamebanana 12345
alphagsm myl4d2 mod add moddb https://www.moddb.com/mods/example/downloads/example-addon-pack
alphagsm myl4d2 mod add workshop ITEM_ID
alphagsm myl4d2 mod add workshop-collection COLLECTION_ID
alphagsm myl4d2 mod add workshop "https://steamcommunity.com/sharedfiles/filedetails/?id=762591677"
alphagsm myl4d2 mod apply
alphagsm myl4d2 mod cleanup

Workshop items use the game AppID 550, rather than server-tool AppID 222860. Both item and collection commands accept IDs or Steam Workshop URLs. AlphaGSM checks the collection and every nested item against 550 before saving additions. Workshop VPKs install as left4dead2/addons/workshop/<item-id>.vpk; enabled desired addons auto-apply before launch. Re-importing a collection adds new items without deleting old ones. Remove an individual entry with mod remove workshop ITEM_ID, then mod apply. Steam can still require an entitled account for some downloads.

To test a public campaign collection and server addon on process and Docker runtimes:

ALPHAGSM_RUN_INTEGRATION=1 ALPHAGSM_RUN_STEAMCMD=1 \
ALPHAGSM_RUN_L4D2_WORKSHOP=1 ALPHAGSM_WORK_DIR=/tmp/alphagsm-work \
PYTHONPATH=.:src python3 -m pytest tests/integration_tests/test_l4d2server.py \
  -k workshop_collection -s

The test defaults to Back To School collection 121115793 and the independent Admin System item 214630948. Set ALPHAGSM_L4D2_WORKSHOP_COLLECTION and ALPHAGSM_L4D2_WORKSHOP_ITEM to override them. The earlier collection 3819008159 returned Valve result 9 (unavailable), so it is no longer the default. The test exercises AlphaGSM create/setup/start/readiness/status/query/info/stop and requires every addon in the running engine's addon load order. File existence alone cannot pass. This proves VPK mounting, rather than client rendering or every gameplay effect. An unavailable collection fails before downloading the server.

Both process and branch-local Docker tests passed on 2026-10-13. Fresh engine output listed all 11 VPKs and showed Admin System executing; real A2S query/info and UDP shutdown also passed. Process shutdown completed normally. Docker used the existing 60-second timeout/kill fallback, so graceful Docker shutdown remains unverified.

The streamed equivalent is ALPHAGSM_RUN_L4D2_WORKSHOP=1 make smoke-test SMOKE_TEST=run_l4d2server.sh. The normal lifecycle test and smoke runner do not require an external Workshop collection unless this option is enabled.

Configuration templates

Reference files from this source revision. Review paths, passwords and game-specific settings before use.

server.cfg

Share your server

Sector Alpha server directory

When your server is ready, you can publish its connection details and community information on Sector Alpha. Review your listing and keep the information current.

Find a community

Browse the directory for game servers and their published connection details.

Browse server directory

Publish your server

Prepare a name, address and description for your listing.

Publish a server

Manual server sharing instructions

Frequently asked questions

What support evidence is recorded for Left 4 Dead 2?

Recorded lifecycle pass. Review the game guide for installation, account, licensing and runtime prerequisites before setup.

Which runtimes can run Left 4 Dead 2?

Declared runtimes: Docker or a Linux host process.

Which ports does Left 4 Dead 2 use?

27015/UDP, 27015/TCP, clientport/UDP. Named port values remain unknown; review the game guide and configuration for additional requirements.

Can I add mods to Left 4 Dead 2?

How should I back up Left 4 Dead 2?

A module-specific backup hook is declared. Review the game guide for its scope, restore procedure and shutdown requirements.

Source and support evidence

This guide mirrors AlphaGSM’s upstream documentation at 32cef5ba9e03053c8e461fffa0ba133b160b528d. Commands and prerequisites can change. Check current support notes before installation.

All game guides