Running a Garry’s Mod dedicated server gives you full control over the game mode, maps, addons, player limits, permissions, and performance settings. Whether you want a private sandbox for friends, a DarkRP community, a Trouble in Terrorist Town server, or a custom modded setup, hosting your own server is the best way to build a stable environment tailored to your players.
Setting up a server is straightforward once the core pieces are in place: SteamCMD for downloading server files, a proper configuration, open network ports, and a plan for addons and administration. The process is similar on Windows and Linux, with a few platform-specific commands and file paths along the way.
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This guide walks through the full setup from requirements to first launch, then covers updates, Workshop content, firewall rules, and common fixes so your Garry’s Mod server is ready for public or private play.
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Garry’s Mod Dedicated Server Requirements
Before you install SteamCMD or download any server files, confirm that the machine you plan to use can run a Garry’s Mod dedicated server reliably. Garry’s Mod is not especially demanding for a small private sandbox server, but performance can drop quickly when you add many players, physics-heavy contraptions, large maps, scripted addons, or custom game modes such as DarkRP, TTT, or Prop Hunt. A stable server depends on four main areas: CPU performance, memory, storage, and network upload speed.
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Minimum and recommended hardware
For a small server with a few friends, an older desktop, a spare PC, a VPS, or a rented dedicated server can work. For a public server with Workshop addons and regular traffic, choose stronger hardware and avoid running other heavy services on the same machine. Garry’s Mod servers usually benefit more from strong per-core CPU speed than from a large number of CPU cores, because much of the game simulation is sensitive to single-thread performance.
| Server size | CPU | RAM | Storage | Network |
|---|---|---|---|---|
| Small private server, 2-8 players | Modern dual-core CPU or better | 2-4 GB available RAM | 10-20 GB free space | 5-10 Mbps upload |
| Medium server, 10-24 players | Fast quad-core CPU | 4-8 GB available RAM | 20-40 GB free space | 10-25 Mbps upload |
| Addon-heavy public server, 24+ players | High-clock modern CPU | 8-16 GB available RAM | 40+ GB free space, SSD preferred | 25+ Mbps upload and low latency |
An SSD is strongly recommended, especially if you plan to use many maps, Workshop addons, or custom content packs. The server can run from a hard drive, but map changes, addon loading, and updates are smoother on solid-state storage. Keep extra free space available for downloaded Workshop content, logs, backups, and future updates. If you install mulle game mode servers on one machine, calculate storage and memory per instance rather than assuming one set of requirements covers everything.
Operating system and software requirements
You can host a Garry’s Mod dedicated server on Windows or Linux. Windows is straightforward for beginners because file paths, firewall prompts, and batch files are familiar. Linux is common for VPS and dedicated hosting because it is lightweight, stable, and easy to manage remotely over SSH. For Linux, use a current 64-bit distribution such as Ubuntu Server or Debian. For Windows, use a supported 64-bit version of Windows 10, Windows 11, or Windows Server.
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- 64-bit operating system: Recommended for stability and proper memory handling.
- Internet connection: Needed for installation, updates, server listing, Workshop downloads, and player traffic.
- Administrator or sudo access: Needed for firewall rules, service setup, folder permissions, and port binding.
- Text editor: Used to edit files such as server.cfg, startup scripts, and game mode configuration files.
You also need access to your router or hosting provider firewall if the server will accept players over the internet. Garry’s Mod commonly uses UDP port 27015 for game traffic, though you can choose a different port if you run mulle servers. For a local-only server, router port forwarding is not required, but the host machine’s firewall must still allow the server process. Once these requirements are in place, the next step is installing SteamCMD and downloading the Garry’s Mod dedicated server files.
Installing SteamCMD and Downloading the Server Files
SteamCMD is Valve’s command-line tool for downloading and updating dedicated server files. Garry’s Mod uses the Steam app ID 4020 for its dedicated server, and you can install it on either Windows or Linux without running the full Steam client. Before you start, create a dedicated folder for SteamCMD and another folder for the Garry’s Mod server files so future updates and backups are easier to manage.
Windows installation
- Create a folder such as C:\steamcmd.
- Create a server folder such as C:\gmodserver.
- Download SteamCMD for Windows from Valve’s official SteamCMD page.
- Extract steamcmd.exe into C:\steamcmd.
- Open Command Prompt and run cd C:\steamcmd.
- Start SteamCMD by running steamcmd.exe.
Once SteamCMD opens, install the Garry’s Mod dedicated server with these commands, replacing the install path if you chose a different folder:
login anonymous
force_install_dir C:\gmodserver
app_update 4020 validate
quit
The login anonymous command is enough for Garry’s Mod server files in most cases. The force_install_dir command tells SteamCMD where to place the server, and app_update 4020 validate downloads the files while checking for missing or damaged content. The first download can take several minutes depending on your connection and disk speed.
Linux installation
On Linux, install SteamCMD through your package manager when available, or download it manually from Valve. For Ubuntu or Debian-based systems, first install common dependencies and create separate folders for SteamCMD and the server. Running the server from a non-root user is recommended for cleaner permissions and better security.
sudo apt update
sudo apt install steamcmd lib32gcc-s1
mkdir -p ~/gmodserver
steamcmd
Inside the SteamCMD prompt, run:
login anonymous
force_install_dir /home/youruser/gmodserver
app_update 4020 validate
quit
If your distribution does not provide a working steamcmd package, create a folder such as ~/steamcmd, download the Linux SteamCMD archive from Valve, extract it, and run ./steamcmd.sh. Keep the server path simple and avoid spaces in folder names, especially if you plan to use scripts, systemd services, or automated update tasks later.
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Verifying the server files
After the download finishes, check the install directory for the main server files. On Windows, you should see files such as srcds.exe. On Linux, look for srcds_run. You should also see folders such as garrysmod, bin, and platform. These files confirm that the dedicated server has been installed in the correct location.
- Windows server launcher: C:\gmodserver\srcds.exe
- Linux server launcher: /home/youruser/gmodserver/srcds_run
- Main configuration folder: garrysmod/cfg
- Addons folder: garrysmod/addons
- Maps folder: garrysmod/maps
To update the server later, run SteamCMD again with the same force_install_dir path and app_update 4020 validate. Using the same directory is essential; otherwise, SteamCMD may download a second copy of the server files into a different folder. After installation, the next step is to configure the server name, password, player slots, default map, and game mode before opening it to players.
Configuring Server Settings and Game Modes
After the Garry’s Mod dedicated server files are installed, the next step is to configure how the server appears, behaves, and loads its game mode. Most basic settings live in the garrysmod/cfg/server.cfg file. If it does not exist, create it as a plain text file named server.cfg inside the cfg folder. This file is executed each time the server starts, making it the best place for hostname, player limits, passwords, voice settings, download behavior, and other persistent options.
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A small private sandbox server can use a simple configuration, while a public roleplay, Trouble in Terrorist Town, or Prop Hunt server usually needs more tuning. At minimum, set a recognizable server name, decide whether the server needs a password, and configure remote console access with a strong rcon_password. Avoid using a weak RCON password, since anyone who gets it can run administrative commands on the server.
hostname "My Garry's Mod Server"
sv_password ""
rcon_password "change_this_to_a_long_random_password"
sv_lan 0
maxplayers 16
sv_voiceenable 1
sv_alltalk 0
sbox_noclip 1
sbox_godmode 0
sbox_playershurtplayers 1
The sv_lan value controls whether the server is LAN-only or available for online play. Use sv_lan 0 for an internet server and sv_lan 1 for local network play. The sv_password line can be left empty for a public server or set to a password for a private group. The maxplayers value can also be set in the startup command with +maxplayers, and startup values may override or interact with config values depending on how the server is launched.
Selecting a Game Mode
Garry’s Mod loads game modes from the garrysmod/gamemodes directory or from mounted Workshop content. The default mode is usually sandbox, but many popular servers run modes such as terrortown, darkrp, prop_hunt, or murder. The game mode is normally selected in the server startup command using the +gamemode parameter.
srcds.exe -console -game garrysmod +map gm_construct +maxplayers 16 +gamemode sandbox
On Linux, the same idea applies with the srcds_run script:
./srcds_run -game garrysmod +map gm_construct +maxplayers 16 +gamemode sandbox
For Trouble in Terrorist Town, you might use +gamemode terrortown with a compatible map such as ttt_minecraft_b5. For DarkRP, the usual value is +gamemode darkrp, but the DarkRP files must be installed correctly before the server can load it. If the server falls back to sandbox or fails during startup, check that the game mode folder name matches the value used after +gamemode.
Common Server Configuration Values
| Setting | Purpose | Example |
|---|---|---|
| hostname | Name shown in the server browser | hostname “TTT Server” |
| sv_password | Restricts access to players with the password | sv_password “friendsOnly” |
| rcon_password | Allows remote console administration | rcon_password “long_random_value” |
| sv_lan | Controls LAN or internet visibility | sv_lan 0 |
| sv_voiceenable | Enables or disables voice chat | sv_voiceenable 1 |
Map selection is also part of the initial configuration. Use a stable, installed map in the startup command with +map. If the map is missing, misspelled, or only available through a Workshop addon that has not loaded, the server may crash, hang, or switch to a fallback map. Start with a default map such as gm_construct or gm_flatgrass while testing, then change to the map required by your chosen game mode once Workshop content and addons are configured.
Once the main settings are in place, restart the server and watch the console output. Look for lines confirming the selected map, game mode, hostname, and player slots. Fix configuration errors early, before adding large addon packs, so it is easier to tell whether a problem comes from the base server setup or from custom content.
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After the Garry’s Mod dedicated server is installed and configured, players still need a network path to reach it. For most home and small-office setups, that means forwarding the correct ports from your router to the machine running the server and allowing the same traffic through the server’s operating system firewall. Garry’s Mod commonly uses UDP 27015 as the main game port, but your exact port depends on the value you use with the server’s -port launch option.
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Assign a Static Local IP Address
Before creating router rules, make sure the server computer keeps the same local IP address. If the router later gives it a different address, the forwarding rule will point to the wrong device and outside players will no longer be able to connect. You can either set a static IP on the server itself or create a DHCP reservation in your router’s admin panel.
- Windows: Run
ipconfigin Command Prompt and note the IPv4 address, default gateway, and network adapter name. - Linux: Run
ip addrorhostname -Ito find the local IP address used by the server. - Router access: Enter the default gateway address in a browser, then sign in to the router’s administration page.
Forward the Garry’s Mod Server Port
In your router, look for a section named Port Forwarding, NAT, Virtual Server, or Applications and Gaming. Create a rule that forwards the Garry’s Mod server port to the static local IP address of your server machine. For a standard setup, forward UDP 27015. If you run mulle Garry’s Mod servers on the same public IP, each server must use a different port, such as 27015, 27016, and 27017.
| Setting | Typical Value |
|---|---|
| Service name | GarrysMod |
| Protocol | UDP |
| External port | 27015 |
| Internal port | 27015 |
| Internal IP | Your server’s local IP address |
Some routers ask for a port range rather than a single port. In that case, enter 27015 as both the start and end port. Avoid forwarding broad ranges unless you have a specific need. If you also use remote administration tools, forward only the ports those tools require and protect them with strong passwords or VPN access.
Allow Traffic Through Windows or Linux Firewall
Router forwarding is only half of the setup. The server machine must also allow incoming traffic. On Windows, open Windows Defender Firewall with Advanced Security, create a new inbound rule for UDP port 27015, and allow the connection on the appropriate network profile. You can also allow the dedicated server executable directly, but a port rule is usually clearer for dedicated hosting.
On Linux, allow the same UDP port using your firewall tool. For UFW, the command is sudo ufw allow 27015/udp. For firewalld, use sudo firewall-cmd --permanent --add-port=27015/udp followed by sudo firewall-cmd --reload. If your server is hosted by a VPS or dedicated server provider, also check the provider’s cloud firewall or security group settings, since those can block traffic before it reaches the operating system.
Once the rules are in place, start the Garry’s Mod server and test from an external connection, not from the same LAN. Ask a friend to connect using your public IP and port, or use the in-game console command connect your.public.ip:27015. If the server is intended to stay private, share the address only with trusted players and use a server password in your configuration.
Adding Workshop Collections, Addons, and Maps
Workshop content is what turns a basic Garry’s Mod dedicated server into a custom experience. Addons can provide weapons, vehicles, tools, models, textures, HUDs, admin systems, and full game mode dependencies, while maps define where players spawn and play. The cleanest way to distribute this content is through a Steam Workshop collection, because clients can automatically download the same addons your server uses instead of hunting for files manually.
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Start by creating a Workshop collection on Steam. Open the Garry’s Mod Workshop, choose Browse, then Collections, and create a new collection for your server. Add the maps and addons you want players to load. Keep the collection focused: too many large addons can slow joining times, increase memory usage, and create conflicts. If you are running a game mode such as Trouble in Terrorist Town, DarkRP, Prop Hunt, or Sandbox with custom tools, include only the content required for that setup.
Once the collection is ready, copy its numeric collection ID from the Steam URL. A collection URL usually looks similar to steamcommunity.com/sharedfiles/filedetails/?id=1234567890, where the number after id= is the collection ID. Add that ID to your server startup command with the +host_workshop_collection parameter. You should also include an authentication key with -authkey, which you can generate from Steam’s game server account management page.
- +host_workshop_collection 1234567890 tells the server which Workshop collection to mount.
- -authkey your_auth_key_here allows the server to access Workshop content reliably.
- +workshop_start_map gm_construct can be used to start directly on a Workshop map when needed.
For a local dedicated server folder, custom non-Workshop addons usually go in garrysmod/addons. Each addon should have its own folder containing files such as lua, materials, models, or sound. Avoid placing random loose files directly into the addons directory unless the addon instructions specifically require it. If an addon includes server-specific configuration files, check its documentation before editing, and keep a backup of any changed files before updating.
Maps can be handled through the Workshop collection or placed manually in garrysmod/maps as .bsp files. To use a map, set it in your startup command with +map mapname, without the .bsp extension. For example, if the file is ttt_minecraft_b5.bsp, the startup parameter is +map ttt_minecraft_b5. If the server starts and immediately changes back to a default map, confirm the map name is spelled correctly and that the game mode supports it.
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After changing collections, addons, or maps, restart the server and watch the console for errors. Lua errors, missing files, and failed Workshop downloads usually appear during startup or when the first player joins. Add content gradually rather than installing dozens of addons at once; this makes it much easier to identify the addon responsible for crashes, conflicts, long load times, or broken game mode features.
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Once the server files, ports, and content are in place, you can start the Garry’s Mod dedicated server with the srcds executable. The exact command depends on your operating system, tickrate preference, player count, map, and gamemode. Run the server from the folder where SteamCMD installed the Garry’s Mod server files, usually a directory containing srcds.exe on Windows or srcds_run on Linux.
Starting the server on Windows
On Windows, create a batch file in the server directory, such as start.bat. This makes launching the server repeatable and prevents you from typing the same command each time. A typical startup command looks like this:
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You can replace gm_construct with your chosen map and sandbox with another installed gamemode, such as darkrp, terrortown, or prop_hunt. If your gamemode needs a specific map, make sure the startup map exists on the server and is available to clients through your Workshop collection or FastDL setup.
Starting the server on Linux
On Linux, launch the server with srcds_run from the installation directory. A common command is:
./srcds_run -game garrysmod +map gm_construct +maxplayers 16 +gamemode sandbox
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If the file is not executable, run chmod +x srcds_run first. For long-term hosting, avoid running the server directly in a normal SSH session, because it will stop when the session closes. Use a terminal mullexer such as screen or tmux, or create a systemd service so the server can run in the background and restart after reboots.
Common startup options
| Option | Purpose |
|---|---|
-console |
Starts the server in console mode, useful for dedicated hosting. |
-game garrysmod |
Tells Source Dedicated Server to load Garry’s Mod. |
+map gm_construct |
Sets the first map loaded when the server starts. |
+maxplayers 16 |
Sets the player slot limit. |
+gamemode sandbox |
Sets the active gamemode. |
-port 27015 |
Uses a specific server port, helpful when hosting multiple servers. |
After startup, watch the console for missing files, Lua errors, failed Workshop downloads, or map load failures. A clean launch should end with the server running on the selected map and accepting connections. You can type commands directly into the server console, including status to view players and connection details, changelevel mapname to switch maps, and quit to shut down safely.
Managing the server day to day
For public servers, install an admin system such as ULX with ULib or another trusted moderation tool. These addons let you assign ranks, kick or ban disruptive players, change maps, run votes, and manage permissions without editing files while the server is live. Keep your server.cfg, gamemode configuration, and addon settings backed up before making major changes.
- Use scheduled restarts: Garry’s Mod servers can accumulate memory usage over time, especially with many addons. A daily restart during low activity helps stability.
- Check logs regularly: Review console output and log files for repeated Lua errors, missing models, or addon conflicts.
- Limit addon changes: Add or remove Workshop items in small groups so problems are easier to trace.
- Monitor performance: High ping, low server FPS, or frequent timeouts often point to overloaded hardware, heavy scripts, or too many physics entities.
Updating the server
Update the dedicated server through SteamCMD using the same app ID used during installation. Shut the server down first, then run SteamCMD and execute an update command such as app_update 4020 validate. The validate option checks server files and replaces damaged or missing ones, but it can take longer than a normal update.
Workshop addons usually update automatically when the server starts and reads the configured collection, but restarting is still required for many changes to fully apply. After a Garry’s Mod or addon update, test the server with a direct connection before announcing that it is ready. Confirm that the map loads, players can join, downloads work, and core gamemode features still function.
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Troubleshooting Common Garry’s Mod Server Issues
Most Garry’s Mod server problems fall into a few categories: connection issues, missing content, addon conflicts, permission mistakes, or performance bottlenecks. When something breaks, check the server console first. Errors printed during startup or map change usually point to the file, addon, Lua script, or configuration value causing the problem. If you run the server through a batch file, shell script, or service manager, make sure logs are being saved so you can review crashes after the process exits.
Players cannot connect to the server
If the server starts but does not appear in the browser, confirm that it is actually listening on the expected port. By default, Garry’s Mod commonly uses UDP 27015, but your startup command may specify another value with -port. Check that your router forwards the same UDP port to the server’s local IP address, and make sure Windows Defender Firewall, iptables, ufw, firewalld, or your hosting provider’s firewall allows inbound traffic. For private testing, connect directly from the Garry’s Mod console with connect your-server-ip:27015. If direct connection works but the server browser does not, verify your server name, gamemode, map, and region filters.
- Local players can connect but internet players cannot: port forwarding or upstream firewall rules are usually wrong.
- No one can connect: the server may be bound to the wrong IP, blocked by the OS firewall, or failing during startup.
- Connection times out after loading: the map, addons, or FastDL/Workshop downloads may be failing or taking too long.
Missing textures, errors, or maps
Pink-and-black textures and red error models usually mean clients are missing required assets. Garry’s Mod often depends on content from mounted games such as Counter-Strike: Source, Team Fortress 2, or Half-Life 2 episodes, depending on the map and addons you use. If a map requires CSS content, installing the map alone will not provide those textures. Use a Workshop collection for required addons and add it to the startup command with +host_workshop_collection. Also confirm that the server has a valid Steam Web API key if your setup uses Workshop downloading options that require it.
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Addons crash the server or break the gamemode
Addon conflicts are common on DarkRP, TTT, Sandbox build servers, and heavily customized roleplay servers. If the server crashes after adding new Workshop items, remove the most recent additions and restart. Then re-add them in small groups until the problem returns. Look for Lua errors mentioning duplicate hooks, missing functions, outdated libraries, or scripts trying to access client-only files on the server. Keep essential frameworks, admin mods, and gamemode files updated, but avoid updating dozens of addons at once on a live server without testing.
| Symptom | Likely cause | First fix to try |
|---|---|---|
| Server crashes on startup | Bad addon, map, or startup parameter | Start with a default map and temporarily disable recent addons |
| Players spawn with errors | Missing Workshop or mounted game content | Check the collection and required game assets |
| High ping or rubber-banding | CPU load, weak network, or too many entities | Lower player slots, remove heavy addons, and monitor usage |
| Admin commands do not work | Incorrect ULX, SAM, or server owner permissions | Verify SteamID64 entries and permission groups |
Performance, lag, and update problems
Garry’s Mod is sensitive to single-core CPU performance, Lua-heavy addons, and excessive physics entities. If tickrate drops or players experience lag, reduce prop limits, NPC counts, vehicle use, and scripted entity spam. Use your admin mod to clean up abandoned props and review addons that run frequent timers or expensive hooks. On Linux, run the server inside screen or tmux while monitoring CPU and memory with tools such as top or htop. On Windows, Task Manager and Resource Monitor are enough for basic checks.
If players receive “server uses different class tables” or version mismatch errors, update the server through SteamCMD and restart it fully. Also update Workshop addons by restarting the server after SteamCMD has completed validation. For stubborn file issues, run SteamCMD again with app_update 4020 validate. Validation can replace modified base files, so keep custom configuration, gamemode edits, and backups separate from default server files where possible.
Frequently Asked Questions
Do I need to own Garry’s Mod to run a dedicated server?
You do not need to own Garry’s Mod just to download and run the dedicated server files through SteamCMD. However, you do need a legitimate copy of Garry’s Mod to join and test the server as a player. If you are using mounted content from games like Counter-Strike: Source, those game files must also be available to players or properly mounted on the server.
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The default Garry’s Mod server port is UDP 27015, and this is the main port you need to forward on your router and allow through your firewall. If you change the server port with the -port launch option, forward that UDP port instead. For public servers, make sure your server is using a reachable public IP address and is not blocked by double NAT or a restrictive ISP firewall.
How much RAM and CPU does a Garry’s Mod server need?
A small private sandbox server can usually run with 2 GB of RAM and a modern dual-core CPU, but public servers with many players, scripted gamemodes, and Workshop addons need more resources. For 20-40 players, 4-8 GB of RAM and strong single-core CPU performance are more realistic. Heavy gamemodes like DarkRP, large maps, and poorly optimized addons can increase usage significantly.
How do I add a Workshop collection to my Garry’s Mod server?
Create a Steam Workshop collection, add the addons and maps you want, then get the collection ID from the collection URL. Add that ID to your server launch options using +host_workshop_collection COLLECTION_ID, and set a valid Steam Web API key with -authkey YOUR_API_KEY. Restart the server after changes so it can download and mount the collection content.
Why is my Garry’s Mod server not showing in the server browser?
First, confirm the server is running without console errors and that UDP 27015, or your chosen server port, is forwarded correctly. Check that your firewall allows inbound traffic to the server executable and that your server has a valid Internet connection. If it still does not appear, try connecting directly with the public IP and port, because the Steam server browser can take time to list new or recently restarted servers.
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Bottom Line
Setting up a Garry’s Mod dedicated server comes down to getting the right files installed, configuring your server settings, opening the correct ports, and testing everything before inviting players. Whether you host on Windows or Linux, a clean setup with sensible addons, regular updates, and proper admin tools will make the server far more stable.
Your next step is to launch the server, connect locally, confirm your map, gamemode, permissions, and workshop content are working, then share the IP with friends or list it publicly. Keep backups of your configuration and monitor performance as your community grows.
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