SKULL BBS: I bolted a dial-up board into a hard hat

Somewhere in the 1980s, if you wanted to find your people, you dialed a phone number and a modem screamed at another modem and you were suddenly somewhere. A board: a little world someone ran out of a spare bedroom, on a machine they owned, run by a person instead of a company. Nothing chose what you saw and nothing sold your attention onward, because there was nobody to sell it to. Just the node, and whoever else was on it that night.

I've been chewing on that idea for a while, and DEF CON 34's theme this year is Agency. Which gave me a definition to chase: the most agency you can have over a corner of the internet is to host it yourself, on hardware you can hold, that answers to nobody.

So I built one. It's called SKULL BBS, it runs Mystic BBS, and it lives inside a hard hat.

Yes, an actual hard hat

The whole board runs on a Raspberry Pi Zero 2 W, bolted into a hard hat, running off a battery pack. There is a tiny OLED on the front of it that scrolls a live ticker.

This is also not my first hard hat. Last year I put a rude offline AI into one and called it HatGPT, which somehow won Smart Wear on the DEF CON Hacker Runway. Apparently I have a whole bit now: put a computer somewhere it has no business being, then wear it out of the house.

The build: a Pi Zero 2 W, a battery, and a lot of wire, all visible through a translucent green shell.

The look is 1985 and unapologetic about it: green phosphor on black, 80 columns, CP437 block art, a skull rendered entirely out of ASCII that grins at you when you log in. There are NO CARRIER jokes. There is a prompt that asks what is your name? and tells first-timers new caller detected. I recolored the entire stock Mystic theme into that green-and-amber palette by hand, byte by byte, because I am not well.

Come call it

The board is only up when the hat is, so start at skullbbs.com. There's a lamp on the page that tells you whether the hard hat is currently awake, and a terminal right there in the browser if you don't have one handy.

When it's lit, you can call it directly:

telnet connect.skullbbs.com 2323

SSH works too, if you'd rather not send your handle in the clear:

ssh -p 2222 -c aes256-cbc bbs@connect.skullbbs.com

(Yes, you need to spell out that cipher. Mystic's crypto library only offers CBC, and I burned an evening at DEF-CON-prep o'clock discovering that SyncTERM-over-SSH and this board refuse to speak to each other because of a version mismatch deep in cryptlib. OpenSSH and PuTTY are happy. Telnet is the universal front door. War story for another post.)

The SKULL BBS ANSI login screen: a green block-art skull in a yellow hard hat beside the words SKULL BBS, a small blue monster labeled marba$, and the taglines 'a bulletin board that lives inside a hard hat', 'telnet/ssh connect.skullbbs.com', and 'new callers welcome · agency · DEF CON 34'. — What you get when you call in: green phosphor, a grinning skull, and a prompt asking your name.

What's actually on it

Once you're in, there are message bases (the job site for general chatter, war stories for scene nostalgia, a wall of callers for one-liners), file areas stocked with the good old stuff (Phrack, cDc t-files, DEF CON history), and a doors menu with things I couldn't help myself building:

gone to hell - a choose-your-own-adventure that goes about how you'd expect.
the defcon trail - it's Oregon Trail, but you're trying to make it to Vegas. You will dysentery.
the wall - a graffiti wall. Leave your mark. Behave, mostly.

The part where the security researcher shows up

I couldn't build a box, hang it on the open internet, and not turn the incoming abuse into a feature.

Breaking into other people's things is sort of my day job, and it's usually the lazy left-open front door that gets you in, not anything clever. So I pointed that lens back at my own board.

The Pi itself has zero inbound ports. It dials out through an encrypted tunnel to a small VPS, which means the thing on my head at the con isn't sitting there with an open door to the world. Password-auth SSH at DEF CON is how the hard hat ends up on someone else's head.

The VPS, though, I left interesting on purpose. There's a Cowrie honeypot sitting where the real SSH port used to be, so the bots and randoms hammering the box with root/root and admin/admin all day long land in a fake shell and get recorded. Then I pipe that catch back into the board itself: there's an intruder log door where you can watch, more or less live, the internet trying to log into my skull. The same feed scrolls across the OLED on the hard hat while I'm walking the con floor.

The OLED on the brim, handing out the number. The same ticker rotates through the honeypot's latest catches.

The credentials people try are grimly predictable, and watching it happen against your own honeypot in real time never stops being funny. I own this box, so I get to decide that getting attacked is content.

Find me at DEF CON 34

The hard hat is coming to Vegas for DEF CON 34, August 6 to 9. If you see a skull with an amber lid scrolling green text at you, come say hi and call the board off my head. First callers from the con get a little something.

And if you can't make it, the number works from anywhere. Check the lamp, then pull up a chair and leave your mark.

-Marbaṩ