The Sentinel Goes Live

Every self-hoster has a box they don’t care about. Mine is an old Dell OptiPlex 9020 Micro — four gigabytes of RAM, a spinning hard drive, and exactly one job: to be the machine that gets compromised so the others don’t have to.

I call it the sentinel. Its job is to watch the dark web for breaches, leaked credentials, and exposed data related to my domains and email addresses. It does this through Tor, reports findings to me over Telegram, and holds nothing of value. If someone breaks into it — and the whole point is that someone eventually will — they find a disposable OpenRouter API key, a Telegram bot token for a dedicated relay, and a machine with nothing else on it.

Zero-credential discipline

The rule is absolute: no real identity, no real credentials, no real data. The sentinel lives on a separate VLAN, uses its own SSH key, runs its own Hermes profile, and connects to nothing on my main network except through a one-way relay.

The only credential it holds is a burner OpenRouter key — identity-buffered so it can’t be traced back to my main account. If the key gets burned, I delete it and generate a new one. The whole machine can be wiped and rebuilt in ten minutes. That’s the point.

The build

Setting up the sentinel took three sessions. The first was hardware: netboot.xyz for the OS, Debian on the 120GB SSD, SSH enabled, firewall locked down. The second was Tor and Hermes: install the Tor SOCKS proxy, verify it routes .onion traffic, install Hermes with a custom SOUL.md that defines its personality as a watchdog that reports but never acts.

The third session was the interesting one: wiring the relay. The sentinel can’t send Telegram messages directly — that would require a bot token on the machine, which is exactly the kind of credential I don’t want there. Instead, it writes findings to a local file, and a separate relay process on my main PC picks them up and forwards them to Telegram.

It’s overengineered by design. The whole point is that the sentinel never talks to the outside world directly. It talks to the relay. The relay talks to Telegram. If the sentinel gets compromised, the attacker gets a relay that forwards to a bot they don’t control.

What it watches

The breach monitor runs hourly. It checks paste sites, known breach databases, and dark web forums for mentions of my domains (maintainai.co.nz, vntis.nz, vaughantaylor.com) and associated email addresses. When it finds something, it sends a summary through the relay: what was found, where, when, and how severe.

So far it’s found nothing alarming. That’s the best outcome — it means nobody cares enough about my domains to dump them. But “nothing alarming” is only useful if you’re actually checking, and that’s what the sentinel does. Every hour, whether there’s something to find or not.

The sentinel isn’t a security solution. It’s a habit. And habits work because they run whether you’re paying attention or not.