UlfWetzker / build-raspbian-image

Builds a minimal Raspbian Stretch image

build-raspbian-image

Builds a minimal Raspbian Jessie image. Based on: https://github.com/niklasf/build-raspbian-image

Login: root
Password: raspberry

Only a basic Debian with standard networking utilities.

❗ Careful: As an exception dropbear is pre-installed and will allow root login with the default password. Host keys are generated on first boot.

Dependencies

Run ./install.sh

Usage

Run ./bootstrap.sh (probably root required for loopback device management) to create a fresh raspbian-yyyy-mm-dd.img in the current directory.

Writing the image to an SD card

dd if=raspbian-yyyy-mm-dd.img of=/dev/mmcblk0 bs=1M && sync

Recommended packages

• Install console-common to select a keyboard layout.

• Install ntp to automatically synchronize the clock over the network. Without a synchronized clock there may be problems when checking validity and expiration dates of SSL certificates. Also dpkg-reconfigure tzdata to select a time zone.

• Install locales. Also dpkg-reconfigure locales and select at least one UTF-8 locale to generate.

• Install iptables for firewall configuration. Sample /etc/network/iptables:

  *filter
  :INPUT DROP [23:2584]
  :FORWARD ACCEPT [0:0]
  :OUTPUT ACCEPT [1161:105847]
  -A INPUT -i lo -j ACCEPT
  -A INPUT -p tcp -m tcp --dport 22 -j ACCEPT
  -A INPUT -p udp -m udp --dport 5353 -j ACCEPT
  -A INPUT -p icmp -m icmp --icmp-type 8 -j ACCEPT
  -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
  COMMIT
  

  Append pre-up iptables-restore < /etc/network/iptables to /etc/network/interfaces.

• fail2ban to ban IPs trying too many wrong SSH passwords for some time. Works without any configuration.

• needrestart, telling you which services to restart after package upgrades.

• Install apt-cron to automatically look for package updates. Regularly updates the package lists (but does not install anything) if installed without any reconfiguration.

• Install avahi-daemon to broadcast the device address to the local network using Zeroconf / Bonjour.

Resize the root partition to the SD card

The default image is effectly about 200MB but actually comes with a 2GB root parition. Its likely the the SD card is much bigger.

1. Boot. Login. fdisk /dev/mmcblk0p1. Delete the partition. Create a new primary ext4 parition.

2. Reboot.

3. Login. resize2fs /dev/mmcblk0p1.

Optimize for heavy RAM usage

Add a swapfile

1. Allocate a continuous file:

   dd if=/dev/zero of=/var/swapfile bs=1M count=512

2. Create a swap file in there: mkswap /var/swapfile

3. Append the following line to /etc/fstab to activate it on future boots:

   /var/swapfile none swap sw 0 0

4. swapon /var/swapfile to activate it right now. swapon -s to show statistics.

Relinquish ramdisks

Remove tmpfs /tmp tmpfs defaults,size=100M 0 0 from /etc/fstab. It makes no sense to have a ramdisk only to swap it to disk anyway.

Optimize for SD card life

Make sure you limit writes to your SD card. /tmp is already mounted as tmpfs (see /etc/fstab). If you do not need logs across reboots you could also mount /var/log as tmpfs.