Applying firewall rules and filters for a Garry's Mod game server

In this article we will be discussing a quick and simple method of securing and setting up your firewall to whitelist and protect your Garry's Mod game-server. Please direct yourself to your filtering/firewall portal and login with the credentials you were providing during onboarding.

Ports & Filters

You'll need to open the following ports for a default Garry's Mod installation

Game Ports (port - protocol - filter)

- 27015 - udp - Half Life 2 / Source Server

The Source Engine Query filter can also be added to the query port to add A2S caching.