Garry's Mod Server Guide

📋 Quick Info

Server Specifications

Game: Garry's Mod (Sandbox Physics Game)
Platform: Source Engine
Default Port: 27015/UDP
Max Players: 128 (default 16-32)
Control Protocol: RCON
Server Binary: srcds_run (Linux), srcds.exe (Windows)
App ID: 4000 (game), 4020 (server)
Special Features: Sandbox building, Lua scripting, Steam Workshop, extensive addons

🔌 Ports & Firewall Configuration

Garry's Mod servers require specific ports for proper operation:

Port	Protocol	Purpose	Required
27015 (configurable)	UDP	Game port	Yes
27015 (same as game port)	UDP	Query/RCON port	Yes
27005	UDP	Client port	No
26900	UDP	Steam master server updater	No
27020	UDP	SourceTV port (if enabled)	No

Firewall Examples

UFW (Ubuntu/Debian):

sudo ufw allow 27015/udp comment 'GMod Game/Query Port'
sudo ufw allow 27020/udp comment 'GMod SourceTV'
sudo ufw allow 26900/udp comment 'Steam Master Server'

FirewallD (CentOS/RHEL):

sudo firewall-cmd --permanent --add-port=27015/udp
sudo firewall-cmd --permanent --add-port=27020/udp
sudo firewall-cmd --permanent --add-port=26900/udp
sudo firewall-cmd --reload

iptables:

iptables -A INPUT -p udp --dport 27015 -j ACCEPT
iptables -A INPUT -p udp --dport 27020 -j ACCEPT
iptables -A INPUT -p udp --dport 26900 -j ACCEPT

⚙️ Installation & Setup

System Requirements

OS: Linux (Ubuntu 18.04+, Debian 9+, CentOS 7+), Windows Server 2012+
CPU: 2.0+ GHz processor (quad-core recommended for large servers)
RAM: 4GB minimum, 8GB+ recommended for addon-heavy servers
Disk: 20GB+ (base game + addons + Workshop content)
Network: Stable broadband connection (more bandwidth for Workshop downloads)

Installation via SteamCMD (Linux)

Install SteamCMD:
sudo apt update sudo apt install lib32gcc1 steamcmd # Debian/Ubuntu # OR for manual install: mkdir ~/steamcmd && cd ~/steamcmd wget https://steamcdn-a.akamaihd.net/client/installer/steamcmd_linux.tar.gz tar -xvzf steamcmd_linux.tar.gz
Download Garry's Mod Server:
./steamcmd.sh login anonymous force_install_dir ./gmod-server app_update 4020 validate quit
Install Counter-Strike: Source Content (Required):
./steamcmd.sh login anonymous force_install_dir ./css-content app_update 232330 validate quit # Create symbolic link to CSS content ln -s /path/to/css-content/cstrike /path/to/gmod-server/garrysmod/addons/cstrike

Installation via SteamCMD (Windows)

Download SteamCMD from Valve's website
Extract to C:\steamcmd\
Run steamcmd.exe and execute:
login anonymous force_install_dir C:\gmod-server app_update 4020 validate quit
Install CSS content similarly and mount it in server configuration

📝 Configuration

server.cfg Example

Create or edit garrysmod/cfg/server.cfg:

// Server Identity
hostname "My Awesome Garry's Mod Server"
sv_password ""                  // Leave blank for public server
sv_steamgroup ""                // Steam Group ID (optional)

// Server Rates
sv_minrate 10000
sv_maxrate 30000
sv_minupdaterate 20
sv_maxupdaterate 66
sv_mincmdrate 20
sv_maxcmdrate 66

// Server Region
sv_region 1                     // 1 = East Coast USA

// Server Visibility
sv_lan 0                        // 0 for internet, 1 for LAN only
sv_logbans 1
sv_logecho 1
sv_logfile 1
sv_log_onefile 0

// RCON (Remote Console)
rcon_password "your_secure_password"
sv_rcon_banpenalty 0
sv_rcon_maxfailures 5

// Contact & Tags
sv_contact "admin@example.com"
sv_tags "sandbox,fun,friendly"

// Gameplay Settings
sbox_maxprops 300               // Max props per player
sbox_maxragdolls 10             // Max ragdolls per player
sbox_maxvehicles 6              // Max vehicles per player
sbox_maxeffects 200             // Max effects per player
sbox_maxballoons 50             // Max balloons per player
sbox_maxlamps 20                // Max lamps per player
sbox_maxthrusters 50            // Max thrusters per player
sbox_maxwheels 50               // Max wheels per player
sbox_maxhoverballs 50           // Max hoverballs per player
sbox_maxnpcs 20                 // Max NPCs per player
sbox_maxsents 100               // Max SENTs per player
sbox_godmode 0                  // God mode (0 = off)
sbox_noclip 1                   // Allow noclip (1 = yes)
sbox_plpldamage 0               // Player vs player damage (0 = off)

// Voice Chat
sv_alltalk 1                    // 1 = everyone can hear, 0 = team only
sv_voiceenable 1

// Download Settings
sv_allowdownload 1
sv_allowupload 1
sv_downloadurl ""               // FastDL URL (highly recommended)

// Workshop Collection
host_workshop_collection "0"    // Your Steam Workshop Collection ID

// Performance
sv_loadingurl ""                // Loading screen URL (optional)
net_maxfilesize 64              // Max downloadable file size (MB)

// Server Protection
sv_pure 0                       // File consistency (usually 0 for GMod)
lua_openscript_cl 0             // Client Lua scripts (security)

// Exec ban files
exec banned_user.cfg
exec banned_ip.cfg

mount.cfg Example

Create garrysmod/cfg/mount.cfg to mount content from other Source games:

// Mount CS:S content (required for most servers)
"mountcfg"
{
    "cstrike"    "C:\css-content\cstrike"
    "tf"         "C:\tf2-content\tf"
    "dod"        "C:\dod-content\dod"
}

Game Mode Configuration

Set game mode in startup parameters:

// Sandbox (default)
+gamemode sandbox

// DarkRP
+gamemode darkrp

// Trouble in Terrorist Town (TTT)
+gamemode terrortown

// Prop Hunt
+gamemode prop_hunt

🚀 Startup Parameters

Parameter	Description	Example
-game	Game directory name	-game garrysmod
-console	Enable console output	-console
-port	Server port	-port 27015
-maxplayers	Maximum players	-maxplayers 32
+map	Starting map	+map gm_flatgrass
+gamemode	Game mode to load	+gamemode sandbox
+exec	Execute config file	+exec server.cfg
-tickrate	Server tickrate	-tickrate 66
-ip	Bind to specific IP	-ip 192.168.1.100
+host_workshop_collection	Workshop collection ID	+host_workshop_collection 123456789
+sv_setsteamaccount	Steam Game Server Login Token	+sv_setsteamaccount YOURTOKENHERE

Example Startup Command (Linux)

./srcds_run -game garrysmod -console -port 27015 -maxplayers 32 \
  +map gm_flatgrass +gamemode sandbox +exec server.cfg \
  +host_workshop_collection YOUR_COLLECTION_ID \
  +sv_setsteamaccount YOUR_GSLT_TOKEN -tickrate 66

Example Startup Command (Windows)

srcds.exe -game garrysmod -console -port 27015 -maxplayers 32 ^
  +map gm_flatgrass +gamemode sandbox +exec server.cfg ^
  +host_workshop_collection YOUR_COLLECTION_ID ^
  +sv_setsteamaccount YOUR_GSLT_TOKEN -tickrate 66

Getting Steam Game Server Login Token (GSLT)

Visit Steam Game Server Account Management
Log in with your Steam account
Create new token with App ID 4000
Use token in +sv_setsteamaccount parameter

🔧 Troubleshooting

Missing Textures/Errors (Purple/Black Checkerboard)

Issue: Players see missing textures or error models.

Solutions:

Install Counter-Strike: Source content (required)
Mount CSS content correctly in mount.cfg
Verify Workshop addons are downloaded
Check FastDL is configured properly
Install additional Source game content (TF2, DOD, HL2:EP2) if needed

Lua Errors on Startup

Issue: Server shows Lua errors in console.

Solutions:

Check addon compatibility with current GMod version
Remove or update problematic addons
Verify Lua files are not corrupted
Check garrysmod/lua/autorun/server/ for conflicting scripts
Review server console logs for specific errors

Workshop Content Not Downloading

Issue: Workshop addons not appearing on server.

Solutions:

Verify Steam Game Server Login Token (GSLT) is valid
Check Workshop Collection ID is correct
Ensure host_workshop_collection is set in startup
Use resource.AddWorkshop() in Lua for individual addons
Check cache/workshop/ directory permissions

High Player Ping/Lag

Issue: Players experiencing latency.

Solutions:

Reduce prop limits if server is heavily populated
Optimize addon count (remove unnecessary addons)
Increase server CPU allocation
Set up FastDL to reduce client download times
Adjust sv_maxrate based on bandwidth

Server Crashes

Issue: Server randomly crashes or restarts.

Solutions:

Check for conflicting addons (disable one at a time)
Review crash logs in garrysmod/ directory
Ensure adequate RAM (8GB+ for large servers)
Update server files with SteamCMD
Remove memory-intensive addons or maps

RCON Connection Issues

Issue: Cannot connect via RCON.

Solutions:

Verify rcon_password is set in server.cfg
Ensure firewall allows UDP on game port
Use correct IP:PORT for RCON connection
Try alternative RCON tools (SourceAdmin RCON, etc.)

🎮 Popular Game Modes

Sandbox

The default GMod experience. Build anything with physics props and tools.

Features: Unlimited creativity, physics manipulation, prop spawning
Best For: Creative building, testing contraptions, relaxed gameplay

DarkRP

Roleplay game mode where players take on jobs in a virtual city.

Features: Jobs (police, mayor, gangster), economy, laws, guns
Best For: Roleplay enthusiasts, social gameplay
Note: Requires DarkRP gamemode addon

Trouble in Terrorist Town (TTT)

Social deduction game. Traitors vs Innocents.

Features: Hidden roles, detective tools, tension and paranoia
Best For: Group play, mystery/deduction fans
Players: 8+ recommended

Prop Hunt

Hide-and-seek with props. Hunters vs Props.

Features: Props disguise as objects, hunters seek them out
Best For: Casual fun, all skill levels

Murder

One murderer, one detective, bystanders. Survive or solve.

Features: Stealth kills, detective investigation, bystander survival
Best For: Tense gameplay, smaller groups

Deathrun

Runners navigate deadly obstacle courses while Deaths activate traps.

Features: Parkour, trap activation, teamwork
Best For: Skill-based challenges

🔌 Addons & Customization

Installing Addons Manually

Download addon files (.gma or folder structure)
Place in garrysmod/addons/ directory
Restart server

Popular Server Addons

ULX/ULib: Admin mod with extensive permissions
DarkRP Mods: Custom jobs, money printers, weapons
Pointshop: Player shop system for cosmetics
PAC3: Advanced player customization
AdvDupe2: Save and load contraptions
Wire Mod: Advanced contraption building
ACF: Armored Combat Framework (vehicles and weapons)

Lua Scripting

GMod servers use Lua for custom functionality:

-- Example: garrysmod/lua/autorun/server/welcome.lua
hook.Add("PlayerInitialSpawn", "WelcomeMessage", function(ply)
    ply:ChatPrint("Welcome to the server, " .. ply:Nick() .. "!")
end)

🛠️ Steam Workshop Integration

Creating Workshop Collection

Open Garry's Mod and go to Main Menu
Click "Workshop" → "Collections"
Create new collection and add desired addons
Publish collection and note the Collection ID
Use ID in host_workshop_collection parameter

Adding Individual Workshop Items (Lua)

In garrysmod/lua/autorun/server/workshop.lua:

-- Add individual Workshop items
resource.AddWorkshop("123456789")  -- Replace with Workshop ID
resource.AddWorkshop("987654321")
resource.AddWorkshop("555555555")

FastDL Configuration

Recommended for faster downloads of custom content:

Set up web server or use hosting service
Compress and upload custom content (maps, materials, models, sounds)
Set sv_downloadurl "http://your-fastdl-url/" in server.cfg
File structure on FastDL must mirror server structure

👤 Admin Commands

Basic Console Commands

status                  # Show players and server info
kick [name/userid]      # Kick player
banid [minutes] [userid]# Ban player
addip [minutes] [ip]    # Ban IP address

changelevel [map]       # Change map immediately
map [map]               # Load specific map

ulx ban [player] [time] # ULX ban command
ulx kick [player]       # ULX kick command
ulx slay [player]       # Kill player

Sandbox Commands

sbox_maxprops [number]      # Set prop limit
sbox_godmode [0/1]          # Toggle god mode
sbox_noclip [0/1]           # Toggle noclip
cleanup                     # Remove all props

📚 Resources

Official Website: gmod.facepunch.com
Steam Workshop: Thousands of addons and maps
GMod Wiki: Lua API Documentation
Forums: Facepunch Studios forums
ULX: ulyssesmod.net

Important Notes

Garry's Mod requires Counter-Strike: Source content (missing textures without it)
Steam Game Server Login Token (GSLT) required for Workshop integration
Supports up to 128 players but 16-32 is typical for performance
Extensive addon ecosystem - Workshop has 500,000+ items
Lua scripting allows virtually unlimited customization
Popular game modes: Sandbox, DarkRP, TTT, Prop Hunt, Murder, Deathrun
FastDL highly recommended for servers with custom content
ULX/ULib most popular admin mod for permissions and management
Server performance depends heavily on addon count and complexity
The possibilities are truly limitless!