Installing Arch Linux on a Raspberry Pi 3

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This article describes a simple approach to build a basic Arch installation with fixed IP address and a few basic utilities. Typically, once complete, I would create a clone of this SD card (see Cloning an SD Card for Raspberry Pi) in order to replicate the installation quickly for other machines etc. This is particularly useful when adding nodes to a cluster (bramble).

Basic Installation

Insert the SD card to be used into a Linux machine and determine the device using e.g. 

   lsblk

The device /dev/sdX should be replaced with the correct device as displayed using the above command.

Start fdisk to partition the SD card: 

   fdisk /dev/sdX

At the fdisk prompt, delete old partitions and create a new one:

  • Type o. This will clear out any partitions on the drive.
  • Type p to list partitions. There should be no partitions left.
  • Type n, then p for primary, 1 for the first partition on the drive, press ENTER to accept the default first sector, then type +100M for the last sector.
  • Type t, then c to set the first partition to type W95 FAT32 (LBA).
  • Type n, then p for primary, 2 for the second partition on the drive, and then press ENTER twice to accept the default first and last sector.
  • Write the partition table and exit by typing w.
  • Create and mount the FAT filesystem:
   mkfs.vfat /dev/sdX1
   mkdir boot
   mount /dev/sdX1 boot

Create and mount the ext4 filesystem: 

   mkfs.ext4 /dev/sdX2
   mkdir root
   mount /dev/sdX2 root

Download and extract the root filesystem (as root, not via sudo): 

   wget http://os.archlinuxarm.org/os/ArchLinuxARM-rpi-2-latest.tar.gz
   bsdtar -xpf ArchLinuxARM-rpi-2-latest.tar.gz -C root
   sync

Move boot files to the first partition: 

   mv root/boot/* boot

Unmount the two partitions: 

   umount boot root

Insert the SD card into the Raspberry Pi, connect ethernet, and apply 5V power. Use the serial console or SSH to the IP address given to the board by your router. Login as the default user alarm with the password alarm, the default root password is root.

Full details of the installation are detailed here:

https://archlinuxarm.org/platforms/armv8/broadcom/raspberry-pi-3

Update the System

   pacman -Suy

Add Users

Follow the instructions here to add a user.

SSH

SSH should be enabled by default. The following command will confirm this. 

   # systemctl status sshd.service

If the service needs to be enabled or started, the following commands can be used as required. 

   # systemctl enable sshd.service
   # systemctl start sshd.service


If you do not already have a public/private key pair, details of how to do this can be fount at https://wiki.archlinux.org/index.php/SSH_keys#Generating_an_SSH_key_pair.

Copy the public key to /home/<user>/.ssh. This can be sone using SSH from another device e.g. to copy a public key to /home/john on a pi with the IP 192.168.1.66, from a Linux/Mac on the same network the following command can be used. 

   cat ~/.ssh/id_rsa.pub | ssh john@192.168.1.66 "mkdir -p ~/.ssh && cat >> ~/.ssh/authorized_keys"

The matching private key should be placed in .ssh directory of the connecting device. Once the keys have been installed, it should be possible connect with SSH using the key rather than a password. All that is required is to change the entries in /etc/ssh/sshd_config to tighten things up a little. 

   PermitRootLogin no
   PubkeyAuthentication yes
   PasswordAuthentication no

Reboot the machine and test SSH. 

   reboot

Sudo

Follow the instructions here to install a SUDO user.

Networking

Set the Hostname

Set the hostname 

   $ nano /etc/hostname

Fixed IP Address

There are several ways to do this, the method I use most frequently is Systemd. To specify a fixed IP, include an eth0.network file in /etc/systemd/network something like the following and reboot (assumes interface is eth0). 

   [Match]
   Name=eth0
   
   [Network]
   DHCP=no
   Address=192.168.1.67/24
   Gateway=192.168.1.254
   DNS=192.168.1.254

If WiFi is required add s the following profile file wlan0.network to /etc/systemd/network (Ensure the IP is set appropriately) 

   [Match]
   Name=wlan0
   
   [Network]
   DHCP=no
   Address=192.168.1.76/24
   Gateway=192.168.1.254
   DNS=192.168.1.254


Install wpa_supplicant e.g. 

   pacman -S wpa_supplicant

Add the following to wpa_supplicant-wlan0.conf 

   ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
   update_config=1
   
   network={
       ssid="<SSID>"
       psk="<password>"
   }

Start wpa_supplicant e.g. 

   systemctl enable wpa_supplicant@wlan0.service
   systemctl start wpa_supplicant@wlan0.service

Base Packages

   $ pacman -S base-devel file git wget

See Also

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