Port 30120: FiveM — Where Los Santos Becomes Whatever You Want

Port 30120 is the default port for FiveM, the multiplayer modification framework for Grand Theft Auto V that transformed a single-player crime simulator into a platform for anything players could imagine.

What Runs on Port 30120

FiveM servers listen on port 30120 for both TCP and UDP traffic.¹ UDP handles the constant stream of game data: player positions, vehicle states, the moment-to-moment chaos of dozens or hundreds of players sharing the same virtual city. TCP handles resource downloads and server browser communication.

When you connect to a FiveM server, your client reaches out to port 30120. If the server is running txAdmin (the management interface), that listens on port 40120.² But 30120 is where the game happens.

The Story of FiveM

The Cfx.re framework that powers FiveM has existed in various forms since 2014.³ It started as CitizenMP, a modification framework for GTA IV and Max Payne 3, created by a developer known online as NTAuthority.⁴ The "what if" was simple: what if players could create their own game modes and custom content in Rockstar's open worlds?

When GTA V came to PC in 2015, NTAuthority adapted the framework. The first public FiveM build went live in February 2015.⁵ The name merges "Five" (from GTA V) and "M" (for Multiplayer).

Rockstar did not welcome this. In August 2015, the company banned three people responsible for FiveM from the Rockstar Social Club, calling it "an unauthorized alternate multiplayer service that contains code designed to facilitate piracy."⁶ The word "FiveM" was blacklisted in Social Club. In November 2015, Take-Two reportedly sent private investigators to the home of one of the banned modders.⁷

The project survived. The team found ways around the restrictions, and FiveM grew. By April 2021, FiveM had 250,000 concurrent players on Steam, surpassing the base game's player count.⁸ It became the dominant way to experience GTA V multiplayer for anyone interested in roleplay, from serious law enforcement simulations to absurdist comedy servers.

In August 2023, Rockstar acquired Cfx.re.⁹ The company that had sent lawyers and investigators eight years earlier now owned the whole thing. Port 30120, once the address of a banned mod, became an official Rockstar property.

The Port

Port 30120 sits in the registered port range (1024-49151). It has no IANA assignment. The FiveM developers chose it, and now it's the de facto standard for an entire ecosystem of custom GTA servers.

To run a FiveM server, you need to open port 30120 for both TCP and UDP on your firewall.¹⁰ Multiple servers on the same machine require different ports: 30121, 30122, and so on.

How to Check What's Listening

To see if something is using port 30120 on your system:

Linux/macOS:

sudo lsof -i :30120
# or
sudo netstat -tlnp | grep 30120

Windows:

netstat -ano | findstr :30120

If you see FXServer or a similar process, you're running a FiveM server. If you see something else, investigate.

Why This Port Matters

Port 30120 represents something that happens in the margins of the Internet: communities building what they want on top of platforms that weren't designed for it. FiveM turned GTA V from a game you play into a platform you build on. Thousands of servers run custom scripts, custom maps, custom rules. Some are serious roleplay experiences where players spend hours as police officers or paramedics. Others are chaos experiments.

The port carries all of it. Every virtual traffic stop, every heist gone wrong, every player living out a life in a digital Los Santos.