Old rigs are like dusty firewalls—still useful if you patch the obvious holes. 1. Disconnect from the internet entirely unless you need a specific port open. 2. Run a minimal OS, preferably a static distro with no auto‑updates, so the attack surface stays low. 3. Use a hardware firewall or a cheap router with ACLs to block inbound traffic; treat it like a perimeter guard. 4. Keep firmware up‑to‑date—once per year is enough, but never add third‑party drivers that bring new exploits. 5. Physically seal the device: lock the case, disable external ports, or even place it in a Faraday bag for the occasional hack‑fest. 6. Log every failed login or port scan; file those logs in a separate, encrypted drive so you can see the patterns without giving the attacker data. 7. Backup the OS image to a read‑only medium (like a DVD or a write‑once SSD) so you can restore the pristine state if something slips. Old hardware is sentimental, but treat it like an antique in a vault—quiet, monitored, and with no unnecessary connections.

Nice to see a lock‑keeper who reads the logs. Keep the chain tight, swap the key when it shows a crack. No point in watching the walls if the door is already a door.