Appendix: BOOMSTICK

Reinstalling Linux on a headless PC or a Raspberry Pi with the official installer is a tedious affair. Before the target machine will accept a remote login, there is a handful of chores to be done by hand, every single time: write the ISO to a stick, borrow a monitor and keyboard, type a WiFi passphrase into iwctl, set a root password or paste in an authorized key, get onto the same network as the target, and clear the machine’s stale entry out of known_hosts.

BOOMSTICK does all of those chores for you, once, at your desk. You write the image to a USB stick, drop your WiFi, WireGuard and SSH settings onto it, and from then on you plug it in, power on, and SSH in from wherever you are. It is what the rest of this book assumes you booted the target machine from.

What’s on the stick

BOOMSTICK is the stock Arch Linux installer – archiso’s releng profile – with a few additions layered on top:

• WiFi, optionally: iwd joins your networks automatically, with wired ethernet preferred when both are available.
• WireGuard, optionally: wg-quick@wg0 brings up a tunnel to your own server at boot, retrying until the endpoint’s DNS name resolves, so the stick has the same address on any network.
• SSH: sshd lets you in as root with your authorized_keys, which is the one thing you must supply. Password login is never permitted.
• A stable identity: the hostname is always arch-iso, and the stick generates its SSH host keys on first boot and keeps them.
• A boot webhook, optionally, which notifies you (via ntfy, for example) with the stick’s LAN, public and WireGuard addresses once it is up.

One image boots both x86_64 PCs (UEFI only) and the Raspberry Pi 5, so a single stick in your bag covers every machine in this book.

The image is generic; the stick is yours

The image itself contains no secrets, so you can build it once, and so can anyone else. Your WiFi passwords, WireGuard key, SSH keys and webhook URL go into an archiso-config/ directory on the stick’s FAT32 partition, which you fill in after writing the image. That partition is readable from any computer, so you edit those files with whatever editor you like, and the live system reads them again on every boot.

The rest of this appendix goes through it in order, beginning with Build the image.