How to make a Garry’s Mod server: ports, addons and admins
Updated 2 November 2026 · 7 minute read · Garry’s Mod (PC), your own PC or a rented server · By Exclsv Support
A Garry’s Mod server is Valve’s free Source dedicated server (SteamCMD app 4020) running on a computer that stays on. Open port 27015, give it a Steam login token so it shows in the server list, and load your addons from one Workshop collection.
What you need
- A Windows or Linux computer that stays on while people play. If it’s your gaming PC, the server stops when you switch it off.
- SteamCMD, Valve’s command-line Steam client. The server downloads without a Steam login; players need their own copy of Garry’s Mod to join.
- About 3 GB of memory for a sandbox or TTT server with 16 players. Big DarkRP addon packs and 64 players want 6 GB or more.
- Access to your router, to forward the port if friends join over the internet.
Install and start it
- Install SteamCMD and open it.
- Type force_install_dir ./gmod (any empty folder), then login anonymous, then app_update 4020 validate. Run app_update 4020 again whenever Garry’s Mod updates.
- Start the server from that folder with ./srcds_run on Linux or srcds.exe on Windows, for example: -game garrysmod +maxplayers 16 +gamemode sandbox +map gm_flatgrass
- Wait for the map to load, then join from Garry’s Mod: open the console with the ~ key and type connect followed by your address.
Ports to open
| Port | Protocol | What it’s for |
|---|---|---|
| 27015 | UDP | Game traffic and the server list. Forward this one. |
| 27015 | TCP | Remote console (RCON). Only forward it if you use RCON from outside your network. |
Change the port with -port 27016 on the start line if 27015 is taken, for example by a second server.
Settings: server.cfg
Most settings live in garrysmod/cfg/server.cfg, which the server reads when it starts and on every map change. A small one looks like this:
- hostname "Our server": the name in the server list.
- sv_password "": leave empty for an open server.
- rcon_password "…": a long password if you use the remote console.
- sv_loadingurl: an optional loading screen page.
The gamemode, map and player limit go on the start line (+gamemode, +map, +maxplayers), not in server.cfg.
The Steam login token
To show in the public server list, a Garry’s Mod server needs a Game Server Login Token (GSLT).
- Sign in at Steam’s Game server account management page (steamcommunity.com/dev/managegameservers). The account can’t be a limited one.
- Make a token for App ID 4000, Garry’s Mod itself (not 4020, the server).
- Add +sv_setsteamaccount YOURTOKEN to the start line. Use one token per server and keep it private: it’s tied to your Steam account.
Without a token, friends can still join with connect and your address.
Addons from the Workshop
- Make a public collection on the Steam Workshop with every addon your server uses.
- Add +host_workshop_collection 1234567890 (the number at the end of the collection’s address) to the start line. The server downloads the collection when it starts.
- So players get the same content when they join, add a Lua file in garrysmod/lua/autorun/server/ with one resource.AddWorkshop("ID") line per addon.
Addons that aren’t on the Workshop go in garrysmod/addons/, one folder each. Players with missing content see purple-and-black checks and big red errors.
Admins
Garry’s Mod has no full admin system of its own. Most servers add ULX with ULib (both on the Workshop, in your collection), then run ulx adduser "YourName" superadmin in the server console to make the first admin. From there, admins use ULX’s menu in game to kick, ban and promote others.
With rcon_password set, you can also run console commands from the game: rcon_password "…", then rcon and the command.
The easy way: on Exclsv
On an Exclsv server you pick the gamemode and map in HQ, paste your Workshop collection on the Mods page, and HQ makes the Steam login token for you. The ports are open already, nothing runs on your PC, and updates install automatically as soon as they’re out (or at your chosen time), with a backup first and one-click undo.
| Size | Memory | Players | Suits | Price a month |
|---|---|---|---|---|
| Friends | 3 GB | 16 | Up to 16 players | £6.99 |
| Community | 4 GB | 32 | DarkRP and TTT run well here | £11.99 |
| Public | 6 GB | 64 | Heavy addon packs | £19.99 |
Garry’s Mod plans and what each includes
If it doesn’t work
The server doesn’t show in the server list
Check the login token is on the start line and hasn’t been deleted, and that UDP 27015 is forwarded to the right computer. A new server can take a few minutes to appear. Friends can join with connect and your address in the meantime.
Players see errors and purple-and-black checks
They don’t have the addon content. Check the collection is public and add a resource.AddWorkshop line for each addon that has models, materials or sounds.
The server stops when I close the window
It runs only while that window does. Leave it open on a computer that stays on, run it as a service, or rent one that runs without your PC.
Friends on your own home network can’t join with the public address
Some home routers don’t let devices inside the house reach the house’s own public address. People at home join with the server PC’s local network address instead; everyone else uses the public one.
Run this on Exclsv: Garry’s Mod server hosting, from £6.99 a month