Running a self-hosted Foxhole dedicated server is a labor of love. You’ve set it up, configured the mods, invited your squad, and then — boom — someone decides to ruin the fun with a DDoS attack. If you’re routing player connections through OpenVPN over UDP, you’re potentially sitting on a well-known amplification vector that attackers love to exploit.
Let’s walk through how to actually defend against this, layer by layer, without making your eyes glaze over.
Why OpenVPN UDP Is a DDoS Target
OpenVPN in UDP mode is fast and efficient, which is exactly why game server admins use it. But that same efficiency becomes a liability when attackers send spoofed packets to trigger responses from your server — amplifying traffic back toward a victim, or simply overwhelming your pipe with junk handshake requests.
The TLS negotiation phase is especially expensive. Without protection, your server will dutifully attempt to respond to every single one of those fake connection attempts. That gets costly fast.
Layer 1: iptables TLS Handshake Rate Limiting
The first thing you should do is throttle how many new UDP connection attempts your server will entertain per second. With iptables, you can use the hashlimit module to cap incoming OpenVPN handshake attempts by source IP.
A rule like this limits new connections to a sane threshold, dropping anything that looks like a flood before it ever touches OpenVPN. It’s not glamorous, but it cuts a huge chunk of volumetric noise right at the kernel level.
Practical Tip
Set your hashlimit burst low — something like 5-10 packets per second per source IP is reasonable for legitimate players. Log the drops for a few days before making the rule permanent so you can tune it without accidentally blocking real users.
Layer 2: OpenVPN tls-auth HMAC Hardening
This one is arguably the most important server-side change you can make. The tls-auth directive adds a shared HMAC signature to every OpenVPN control packet. Any packet arriving without that pre-shared key gets dropped instantly — before any TLS processing even begins.
This single configuration line essentially makes your server invisible to attackers who don’t have your key. No key, no handshake, no CPU burn. Add tls-auth ta.key 0 to your server config and distribute the key securely to your players.
Practical Tip
Generate a fresh ta.key with openvpn --genkey --secret ta.key and rotate it periodically. Treat it like a password — don’t paste it in your Discord.
Layer 3: Voxility BGP Scrubbing as Upstream Protection
When volumetric attacks exceed what your server’s NIC or upstream link can handle, host-based rules aren’t enough. This is where Voxility’s BGP-announced scrubbing infrastructure becomes a game changer. By announcing your IP prefixes through Voxility, attack traffic gets absorbed and filtered at their network edge before it ever reaches your server.
It’s a genuine upstream moat. Legitimate traffic passes through clean; the garbage gets dropped in the scrubbing center. For game servers that need low latency and high availability, this kind of always-on protection is hard to beat.
Putting It All Together
These three layers work best in combination. iptables handles the small stuff at the edge of your OS. tls-auth kills spoofed handshake abuse cold. And Voxility catches the big volumetric floods before they even reach your machine.
If you’re not sure how to tune these for your specific setup, professional DDoS protection consulting is available to help you design a stack that fits your infrastructure and budget.
Under Attack Right Now?
Don’t wait it out hoping the attacker gets bored. Open a support ticket immediately and get expert eyes on your situation. The faster you act, the less downtime your players suffer — and the less likely the attacker is to come back for round two.
