field notes
Hardening a Self-Hosted Game Server (2026): The Pre-Launch Security Checklist
A self-hosted game server is a public service on the open internet, and most of them are secured like a LAN box: RCON open on 0.0.0.0, password SSH, an OS that has not seen an update since install, no firewall. Here is the checklist to run before you open a port, concrete, game-server-specific, and ordered by how much risk each step removes.
Game-server hardening content is oddly thin. There is plenty of generic Linux advice and almost nothing that names the game-specific traps, RCON binding, mod privileges, the ports that actually need to be open. This is that list. Work top to bottom before the server is reachable from the internet; each item removes a category of attack, and the order roughly follows how often each one is what actually gets a box owned.
1. Firewall to the game ports and SSH only
Default-deny inbound, then open exactly the ports the game needs plus SSH. Nothing else. The most common mistake is a fresh box with no firewall at all, exposing every service that happens to be listening, database ports, the RCON port, a web panel, a stray dev server. Look up your game's actual port list (query port, game port, and any separate ports it uses) and open only those. If your admin access can be restricted to a known IP or a small range, restrict SSH to it too.
Use the tooling your distro ships: ufw or firewalld in front of nftables is fine for a single box, and a cloud provider's network firewall is even better because it drops traffic before it reaches the machine. The test is simple: from outside your network, a port scan should show the game ports and SSH, and nothing you did not intend.
2. SSH: keys only, no passwords, no root login
Password SSH on a public IP is a losing game: automated bots try common usernames and passwords against every reachable server, continuously. Generate a key pair, install the public key, then in sshd_config set PasswordAuthentication no and PermitRootLogin no, and reload SSH. Log in as an unprivileged user and use sudo for admin tasks. Moving SSH off port 22 cuts log noise but is not security by itself; the real control is disabling passwords entirely.
This single change removes the entire brute-force category, which is the most common way a hobby server gets compromised. If you must keep a password path for emergencies, gate it behind the firewall rule from step one so it is never exposed to the whole internet.
3. RCON: never on 0.0.0.0
This is the game-specific one people miss. RCON is the remote admin protocol for most dedicated servers (Source RCON, and the equivalents in Minecraft, Rust, ARK and others), and it is frequently left bound to 0.0.0.0, meaning any host on the internet can reach it. Combined with a weak or default password, or a protocol that sends credentials in the clear, that is a direct path to running admin commands on your server.
The fix has two acceptable forms. Best: bind RCON to 127.0.0.1 (localhost) and reach it through an SSH tunnel when you need it, so it is never exposed at all. Acceptable: keep it reachable but put it behind a long random password and a firewall rule that only allows your admin IP. What is never acceptable is RCON on 0.0.0.0 with a guessable password. Check the bind address explicitly; do not assume the default is safe, because for several games it is not.
4. Patch the game build and the OS
Two separate patch streams, and self-hosters usually forget one of them. The game build needs updating because server binaries ship security and stability fixes, and running months behind is running known bugs. The operating system needs updating because that is where the serious remote vulnerabilities live; enable unattended security updates so the base OS patches itself, and reboot when the kernel asks.
The discipline that ties them together: never auto-update a game build blindly on a server people care about (a bad patch can break saves or mods), but never let the OS drift either. Take a backup, then update the game deliberately; let the OS security updates run automatically. The gap between "I installed it once" and "I keep it patched" is where a lot of compromises happen.
5. Rate-limit and fail2ban
Even with password SSH disabled, install fail2ban (or an equivalent) to watch auth logs and temporarily ban IPs that hammer your services. It is a cheap, defence-in-depth layer that cuts log noise, slows down any probe that does slip through, and gives you a record of who is knocking. Point it at SSH at minimum, and at any other authenticated service you expose.
Where the game supports it, apply the same instinct in-game: connection rate limits, allow or block lists, and a query-port limiter blunt the low-effort spam and malformed-packet probes that game servers attract. This will not stop a real DDoS (step seven), but it handles the constant background nuisance traffic.
6. Do not run the server as root
Run the game as a dedicated unprivileged user, never as root. Game servers are large C++ or engine binaries that also load your mods, so a memory-safety bug or a malicious mod is a real code-execution surface. If that process is root, a single exploit is a total machine compromise. If it is a locked-down service account, the same exploit is contained to that account's files.
Create a gameserver user, own the install directory to it, and run the process under a systemd unit with that user set. While you are there, systemd gives you cheap extra containment, NoNewPrivileges, ProtectSystem, a private /tmp, so the blast radius of a bad day stays small. This is one of the highest-value, lowest-effort items on the list.
7. DDoS mitigation is upstream, not on the box
Game servers are among the most common DDoS targets, low effort to attack, high emotional payoff for whoever is angry about a ban or a match. The uncomfortable truth is that you cannot solve this on the server. A volumetric attack saturates your inbound pipe before your firewall ever sees the packets, so mitigation has to happen upstream, at the provider or the network edge, where there is enough capacity to absorb and filter it.
Practically: choose a host or transit that includes real DDoS protection, and understand what "protected" actually means on their plan, because the word is heavily marketed and unevenly delivered. For a home-hosted server this is the single strongest argument for putting a protected VPS or proxy in front of your residential connection rather than exposing your home IP directly. Our DDoS reality piece separates the genuine mitigation from the marketing.
8. Backups you have actually restored
Security includes surviving the bad day: a corrupted save, a bad update, a ransomware-style compromise, or a mod that eats your world. Automate regular backups of the save data and server config, keep at least one copy off the machine (a compromised or dead box takes its local backups with it), and, the part everyone skips, actually restore one to confirm it works. An untested backup is a guess, and you find out it was a bad one at the worst possible moment.
Match the cadence to how much progress you are willing to lose. A busy survival server justifies frequent snapshots; a small weekend world can back up nightly. Either way, verify the restore before you need it.
9. Mods are a supply chain
The last item is the one game servers uniquely have to worry about. Server-side mods and plugins run with your server's privileges, so every mod is code you are choosing to execute, and the mod list is a supply chain, not a wishlist. A malicious plugin, or a legitimate one whose account or distribution got compromised, is a direct path onto your box, which is exactly why step six (non-root) matters so much.
Install mods only from sources you trust, prefer well-maintained projects with active authors over abandoned ones, pin to specific versions rather than blindly pulling latest, and read what a plugin actually asks to do before you grant it. When a mod goes unmaintained, treat that as a security signal, not just a compatibility one. The convenience of "just add the mod" is real, and so is the risk behind it.
Run the whole list before you open a port
None of these steps is exotic, and that is the point: the compromises that hit self-hosted game servers are almost never clever, they are open RCON, a guessed SSH password, an unpatched OS, or a sketchy mod running as root. Work the list top to bottom before the server is reachable, and you have removed the categories that account for the overwhelming majority of incidents. If you are still deciding whether to self-host at all, weigh it against a managed host that handles patching and DDoS for you, our self-host vs rent guide frames that trade, and a good general reference for the OS layer is the Arch Wiki security guide, which applies well beyond Arch.
FAQ
- What is the single most important thing to secure on a game server?
- Two steps tie for first: a firewall that exposes only the game's own ports plus SSH, and disabling SSH password login in favour of keys. Together they remove the two most common ways a self-hosted box gets taken over.
- Should I expose RCON to the internet?
- No. Bind RCON to localhost and reach it over an SSH tunnel, or at minimum put it behind a strong password and a firewall rule. RCON open on 0.0.0.0 with a weak or default password is one of the most common game-server compromises.
- Do I need DDoS protection for a game server?
- Game servers are among the most common DDoS targets, and mitigation has to happen upstream at the provider or network edge, not on your box. Choose a host or transit that offers it; you cannot filter a saturating attack from inside the server.
- Is it safe to run mods on a dedicated server?
- Only from sources you trust. Server-side mods run with the server's privileges, so a malicious or compromised mod is a code-execution path. Pin versions, avoid unmaintained mods, and treat the mod list as a supply chain.
- Should I run my game server as root?
- No. Run it as a dedicated unprivileged user so a bug in the game or a mod cannot trivially become full control of the box.