FiveM Anticheat & Server Security Best Practices

A compromised FiveM server is not just an inconvenience — it can destroy weeks of community building overnight. Money menus, vehicle spawners, and event injection tools are freely available, and your server is a target the moment it appears in the server list. The good news is that a layered security approach makes exploitation dramatically harder.

This guide covers every layer of the FiveM security stack: the server-authoritative foundation that OneSync provides, the ace permission system that controls what players and resources can do, rcon hardening, artifact update discipline, txAdmin password hygiene, and the realistic role that third-party anticheats play. Work through each section and your server will be in far better shape than the majority of servers on the list.

The Core Principle: Never Trust the Client

Everything else in this guide builds on one rule: never trust data that comes from a client-side script. A cheater's client can fire any network event with any payload. If your server-side handler receives a `givePlayerMoney` event and blindly adds whatever amount the client sends, any player with a menu trainer can give themselves unlimited money.

Every consequential action — transferring money, giving items, spawning vehicles, changing job grades — must be validated and executed on the server side. The client should only send intent ("I want to buy this item"), never outcome ("add this item to my inventory with this weight"). The server checks whether the action is permitted, then applies it.

OneSync: The Server-Authoritative Foundation

OneSync shifts entity management from clients to the server. In the legacy networking model, clients had significant authority over their own entities — a model that cheaters exploited heavily with god-mode, position teleportation, and entity manipulation. With OneSync enabled, the server controls which entities exist and what state they hold, which closes many of those attack surfaces by design.

# server.cfg — enable OneSync
set onesync on

# Confirm it loaded in the startup console output
# OneSync is required for > 32 slots and strongly recommended for all servers
# It is not a complete anticheat by itself — combine with server-side validation

Ace Permissions: Locking Down What Resources and Players Can Do

FiveM's ace (access control entry) and principal system is the built-in authorization layer for server commands and resource-declared permissions. Every sensitive command — kicking players, spawning vehicles, accessing admin menus — should be gated behind an ace that only privileged principals hold.

How add_ace and add_principal Work

Permissions are declared as aces and assigned to principals (groups or individual identifiers). Players are then added to principals. The server checks this chain before allowing any ace-protected action.

# server.cfg — example ace permission setup

# Define what the 'admin' group is allowed to do
add_ace group.admin command.kick allow
add_ace group.admin command.ban allow
add_ace group.admin command.noclip allow
add_ace group.admin command.add_ace allow
add_ace group.admin command.add_principal allow

# Grant the built-in 'god' group full access
add_ace group.god command allow

# Add a specific player steam ID to the admin group
add_principal identifier.steam:110000112345678 group.admin

# Add the admin group as a principal of the moderator group (inheritance)
add_principal group.admin group.moderator

# Restrict a resource's internal command so only the resource itself can call it
add_ace resource.my_admin_resource command.internalAdminCmd allow

Never leave the default `add_principal identifier.steam:... group.god` entries pointing at accounts you do not personally control. Audit your server.cfg ace block every time a staff member leaves your team.

Least-Privilege Rule

Grant only the permissions a role actually needs. A moderator who handles rule violations does not need `command.add_ace` — that command can be used to escalate privileges. Keep `command.add_ace` and `command.add_principal` restricted to the server owner's identifier only.

Hardening rcon

rcon gives whoever holds the password full console access to your server — they can kick players, execute arbitrary commands, and restart resources. Treat it accordingly.

• Use a long random password (32+ characters, mixed alphanumeric and symbols) if you use rcon at all.
• If you manage your server entirely through txAdmin, consider leaving rcon_password unset or setting it to an unused random string.
• Never share the rcon password with moderators or junior admins — they should use txAdmin's own role system instead.
• Restrict your server's port to known IP ranges at the firewall level where possible.
• Rotate the rcon password immediately if any staff member with access leaves.

Keeping Server Artifacts Updated

FiveM ships security fixes in server artifact updates. Running an outdated artifact means known exploit mitigations are not applied to your server. Check artifacts.fivem.net regularly and update during a scheduled maintenance window. The process takes under five minutes: stop the server, replace the FXServer binary, restart.

txAdmin Security

txAdmin is the web-based server management panel used by the majority of FiveM servers. It is a high-value target because admin access to txAdmin is equivalent to console access to the server.

• Use a strong, unique password for your txAdmin master account — never reuse passwords from other services.
• Enable 2FA in txAdmin if your version supports it.
• Do not expose txAdmin's web interface to the public internet without a firewall rule or VPN requirement.
• Create separate txAdmin accounts for each staff member with appropriate permission levels — do not share the master account.
• Review txAdmin action logs periodically to detect unauthorized admin actions.

Threat Landscape and Mitigations

Where Third-Party Anticheats Fit

Tools like FiveGuard and similar third-party anticheat solutions add a detection-and-ban layer on top of your server's built-in protections. They monitor for known cheat signatures, inject detection hooks, and automate bans. They are genuinely useful as a supplementary layer — but they are exactly that: supplementary.

A third-party anticheat cannot compensate for scripts that trust the client. If your economy script accepts money amounts from client events, no anticheat will reliably catch every player abusing it before damage is done. Fix the root cause first, then add anticheat as an extra layer of defense.

Quick Security Checklist

1. Enable OneSync (`set onesync on`) in server.cfg.
2. Audit all server-side event handlers — validate every piece of client-supplied data.
3. Review and tighten your ace/principal block in server.cfg; remove unused entries.
4. Set a strong rcon_password or disable rcon if unused.
5. Update your FXServer artifact to the latest recommended version.
6. Secure txAdmin with a strong unique password and per-staff accounts.
7. Rate-limit sensitive server events to prevent flood/DoS abuse.
8. Consider a supplementary anticheat (FiveGuard or equivalent) as an additional layer.
9. Schedule regular server restarts via txAdmin to maintain stability.
10. Rotate credentials and audit staff permissions whenever team membership changes.

Conclusion

FiveM server security is not a product you install — it is a set of design decisions, configuration choices, and ongoing maintenance habits. The foundation is always server-side validation and server-authoritative networking via OneSync. The ace permission system, rcon hardening, artifact updates, and txAdmin hygiene are the layers that protect your management surface. Third-party anticheats are a useful addition, not a substitute for any of the above.

All server packs and custom scripts from CRM Development are built with server-side validation as a non-negotiable default. Whether you are running a serious roleplay environment, a street-life server like 100K or Die, or a semi-serious community, the security architecture matters as much as the content. Get the foundation right and your moderation team can focus on the community instead of fire-fighting exploits.