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Raspberry Pi

I use a lot of Raspberry PIs. I want bootstraping them from a fresh SD card to be quick and painless, but I want to preconfigure the network settings and the SSH authentication config from first boot.

Raspbian First Boot Setup

  1. Download Raspberry Pi OS Lite from https://www.raspberrypi.com/software/operating-systems/
  2. Uncompress with xz -d

  3. Use main.go to get the mount point offsets

    go run main.go ./2023<imagename>

  4. Mount first mount point (this is /boot). Example (Your offsets may vary!):

    mount -v -o offset=272629760,loop ./2022-09-22-raspios-bullseye-arm64-lite.img /mnt

  5. Inside the mountpoint add the following files

    • Setup userconf (see password manager for contents) - this creates the default user. It looks like this: admin:$<PASSWORED HASH>. The contents can be generated with password.py

    vim /mnt/userconf

  6. Enable SSH on boot:

    touch /mnt/ssh

  7. Copy firstboot.sh setup script:

    cp firstboot.sh /mnt/firstboot.sh

  8. umount the boot partition

  9. Then mount the second mount point (this is the root / partition)
  10. Add firstboot.service to /mnt/lib/systemd/system/firstboot.service

  11. Enable the service:

    cd /mnt/etc/systemd/system/multi-user.target.wants && ln -s /lib/systemd/system/firstboot.service .

  12. Edit /mnt/etc/ssh/sshd_config, add these lines:

        PasswordAuthentication no
    PermitRootLogin no

  13. Setup pi user's SSH config. Note! Even if your user is not pi, put it in /home/pi anyways, the system will rename it on first boot.

    cd /mnt/home/pi
mkdir .ssh
chmod 0700 .ssh
chown 1000:1000 .ssh
# add your keys to .ssh/authorized_keys
chown 1000:1000 .ssh/authorized_keys
chmod 0600 .ssh/authorized_keys

Finally, umount the partition, then rename your .img file to something you'll recognize as being first-boot ready:

mv 2022-04-04-raspios-bullseye-armhf-lite.img 2022-04-04-raspios-bullseye-armhf-lite-firstboot-ready.img