Module A3 · Operate & secure

DDoS, proxy, and networking basics

Owners ask the same three questions: why can nobody join, why does it lag under load, and why am I getting attacked. This lesson gives you the mental model and a tiny resource that prints your live networking config so the numbers stop being abstract. You will not become a network engineer, but you will stop guessing and know what to check and what to ask your host.

You'll learn: Why your server is unreachable or laggy, what a proxy/filter actually does, and which ports matter.
Time: ~20 minutes.
You need: A server you can reach (local or VPS) and access to its firewall settings.
You'll learn: Ports -> why connections fail -> what DDoS protection does -> when to use a proxy/filter -> what hosting handles for you

BEFORE YOU START

Build it

We are going to make the networking config concrete. This is a server-only resource that reads your live network settings and prints them to the console, so the ports, the OneSync mode, and the player cap stop being words in a guide and become numbers you can see. Follow the names exactly. Once it prints, the next section takes it apart and explains what each number controls.

Make the resource folder

The server has one folder for this lesson.

Inside your server's resources folder, create this folder:

code

resources/qu_networking_basics

Create the files

Every file named in the manifest exists.

Create this exact file layout:

code

resources/qu_networking_basics/
fxmanifest.lua
server.lua

Set the endpoints in server.cfg

The server binds TCP and UDP on the same port.

Open server.cfg. Near the top, where your other networking lines live, make sure both endpoints are declared on the same port:

code

endpoint_add_tcp "0.0.0.0:30120"
endpoint_add_udp "0.0.0.0:30120"

0.0.0.0 means "listen on every network interface on this machine", and 30120 is the port players connect to. If you only ever see one of these lines in a guide, add the other. The TCP line alone gets you a handshake but no gameplay; the UDP line alone gets you gameplay the handshake never reaches.

Write fxmanifest.lua

FiveM knows which file to load.

Open fxmanifest.lua and paste this:

code

fx_version 'cerulean'
game 'gta5'

server_script 'server.lua'

No lua54 line. As of June 2025 that directive is deprecated and ignored, because Lua 5.4 is now the only Lua runtime.

Write the lesson code

The topic is now a runnable probe of your real config.

Open server.lua and paste this:

code

RegisterCommand('netinfo', function()
    local port = GetConvarInt('netPort', 30120)
    local maxClients = GetConvarInt('sv_maxClients', 48)
    local oneSync = GetConvar('onesync', 'off')

    print('[qu_networking_basics] game port (TCP+UDP): ' .. port)
    print('[qu_networking_basics] txAdmin panel port:  40120')
    print('[qu_networking_basics] sv_maxClients:        ' .. maxClients)
    print('[qu_networking_basics] onesync:              ' .. oneSync)
end, true)

Keep reading the full lesson

Still ahead in this lesson

How it works
If something went wrong
What you can do now
Try it yourself

Build it

Make the resource folder

Create the files

Set the endpoints in server.cfg

Write fxmanifest.lua

Write the lesson code

Keep reading the full lesson

Start and test it