Flash eMMC with latest Debian image

  1. Download Debian image [whatever].img.xz
    unxz bone-debian-7.8-lxde-4gb-armhf-2015-03-01-4gb.img.xz
  2. Insert microSD card and make sure that it is unmounted
    • lsblk
    • fdisk -l
  3. Copy the img to the microSD card

    sudo dd bs=4 if=bone-debian-7.8-lxde-4gb-armhf-2015-03-01-4gb.img of=/dev/mmcblk0 conv=fsync

    This step will take a lot of time.

  4. Mount the microSD card and make sure it flashes to the beaglebone:

    sudo mount /dev/mmcblk0p1 /mnt/sd-card
    vim /mnt/sd-card/boot/uEnv.txt

    Uncomment the line:

  5. Hookup the USB-to-serial cable
    • Connect Black Wire to Pin 1 (closest to 5v barrel)
    • Connect Green Wire to Pin 4 (2 pins from pin 1)
    • Connect White Wire to Pin 5
  6. Connect to USB, check output of dmesg for which /dev/ the serial connection is on
  7. Connect to serial connection via screen

    screen /dev/ttyUSB0 115200
  8. put sdcard in BBB and power up, hold the S2 button, power up
  9. Wait, the status lights will flash in a cylon pattern, you can watch the eMMC flash progress via screen
  10. All User LEDs should be solid on completion

More info is available on the BeagleBoneBlack Wiki

Initial setup

Connect over SSH

To connect via ssh: plugin beaglebone to computer via SSH

ssh -l root

Wifi Setup

  1. Plugin the wifi adapter
  2. Reboot (unplug it and plug it back in)
  3. Generate your pre-shared key using wpa_passphrase (see Debian Wiki)
  4. vim /etc/network/interfaces

    auto wlan0
    iface wlan0 inet dhcp
        wpa-ssid "network-name"
        wpa-psk "network-password"
  5. ifdown wlan0; ifup wlan0
  6. use ip -o addr show to confirm that you have an ip address

Update debian

Use the Debian Upgrade Script to update debian:

#!/usr/bin/env bash
# Debian auto-upgrade script
# https://debian-handbook.info/browse/stable/sect.automatic-upgrades.html

# kill all cached creds
sudo -k

# ask for new creds
sudo -v

export DEBIAN_FRONTEND=noninteractive
sudo apt-get update
yes '' | sudo apt-get -y -o Dpkg::Options::="--force-confdef" -o Dpkg::Options::="--force-confold" dist-upgrade

Basic security

Make a root password

  • Install pwgen: sudo apt-get install pwgen
  • Generate a root password: pwgen -Bsy 16 1
  • Store that password in your password store—you’ll never remember it
  • Login to beaglebone via ssh, run passwd

Add a privileged non-root user

  • Generate a non-privileged user password: pwgen -Bsy 16 1
  • Save password in password store
  • Add the user

    sudo groupadd sudo-user
    sudo groupadd ssh-user
    useradd tyler
    mkdir /home/tyler
    mkdir /home/tyler/.ssh
    touch /home/tyler/.ssh/authorized_keys
    chown -R tyler:tyler /home/tyler
    chmod 700 /home/tyler/.ssh
    chmod 600 /home/tyler/.ssh/authorized_keys
    usermod -a -G sudo-user tyler
    usermod -a -G ssh-user tyler
    usermod --shell /bin/bash tyler
    passwd tyler
  • give that user sudo privileges
    • EDITOR=vim visudo -f /etc/sudoers.d/sudo-user
    • Add the line: %sudo-user ALL=(ALL) NOPASSWD:ALL
  • Add your laptop’s key to user’s authorized_keys

    # This should happen from your local machine: laptop/desktop/whatever
    cat ~/.ssh/id_rsa.pub | ssh -l tyler 'mkdir -p .ssh && cat >> ~/.ssh/authorized_keys'

Remove demo user

  • userdel -fr debian

Lockdown ssh

  • Generate better hostkeys

    cd /etc/ssh
    rm ssh_host_*key*
    ssh-keygen -t rsa -b 4096 -f ssh_host_rsa_key < /dev/null
  • Modfiy /etc/ssh/sshd_config to make it like below:

    Ciphers aes256-ctr,aes192-ctr,aes128-ctr
    KexAlgorithms diffie-hellman-group-exchange-sha256
    MACs hmac-sha2-512,hmac-sha2-256,hmac-ripemd160
    Protocol 2
    HostKey /etc/ssh/ssh_host_rsa_key
    PubkeyAuthentication yes
    PermitRootLogin no
    PasswordAuthentication no
    AllowGroups ssh-user
  • Restart SSH service ssh restart
  • Open a new terminal window and make sure you can still login (you may need to delete and reaccept hostkeys)

Fun Stuff

  • Change ssh banner:

    sudo apt-get install figlet
    awk '$1 !~ /default/' /etc/issue.net > ~/issue.net && sudo mv ~/issue.net /etc/issue.net
    sudo sh -c 'figlet BeagleBone >> /etc/issue.net'
  • BeagleBone pin-out

Things to remember

thank god for 1wire temp sensor blog posts: