Prepare a headless Raspberry Pi 3 with Arch Linux ARM to connect to WiFi
Prepare the SD-card to use for the Raspberry Pi 3 by following the official documentation for Arch Linux ARM.
Prepare headless operation
It is expected that the root file system on the SD-card is mounted on your system at /mnt/root.
Beware that both root and alarm user has default passwords, hence the Pi should never be put on an untrusted network before those are changed (there’s a reason the username is alarm).
dhcpcd take care of wireless networking (it’s not handling wired
connections with this setup):
# ln -s /usr/lib/systemd/system/dhcpcd@.service /firstname.lastname@example.org
Add a hook so that
dhcpcd can take care of starting
# ln -s /usr/share/dhcpcd/hooks/10-wpa_supplicant /mnt/root/usr/lib/dhcpcd/dhcpcd-hooks/
wpa_supplicant configuration file with your wifi connection details
# echo "ctrl_interface=DIR=/var/run/wpa_supplicant" > /mnt/root/etc/wpa_supplicant/wpa_supplicant-wlan0.conf # wpa_passphrase "My SSID" "My passphrase" >> /mnt/root/etc/wpa_supplicant/wpa_supplicant-wlan0.conf
Place your public key inside root user’s SSH configuration directory to allow for root login
# mkdir /mnt/root/root/.ssh # chmod 0700 /mnt/root/root/.ssh # cat ~/.ssh/id_rsa.pub > /mnt/root/root/.ssh/authorized_keys # chmod 0600 /mnt/root/root/.ssh/authorized_keys
Boot up the Pi and it should connect to the wireless network you specified automatically on boot.
When I’m unsure what IP a device on my network has got, I use
# arp-scan -l Interface: wlp3s0, datalink type: EN10MB (Ethernet) Starting arp-scan 1.9.5 with 256 hosts (https://github.com/royhills/arp-scan) 192.168.1.1 xx:xx:xx:xx:xx:a6 xxx 192.168.1.22 xx:xx:xx:xx:xx:24 xxx 192.168.1.26 xx:xx:xx:xx:xx:a4 Raspberry Pi Foundation 3 packets received by filter, 0 packets dropped by kernel Ending arp-scan 1.9.5: 256 hosts scanned in 2.013 seconds (127.17 hosts/sec). 3 responded
Then attempt SSH
$ ssh email@example.com -i ~/.ssh/id_rsa Last login: Mon Jul 22 14:30:50 2019 from 192.168.1.19 [root@alarm ~]#
Apparently, I need to get
Network time synchronisation
I had troubles using
systemd-timesyncd, as it was failing all the time.
And, initially, I had problems with the default config of
openntpd, but got
it working by avoiding hostnames for the
server directives, and instead
using plain IPv4 addresses. I got the IPs of the DNS records of
dig +short pool.ntp.org).
/etc/ntpd.conf (on the Pi):
server 22.214.171.124 server 126.96.36.199 server 188.8.131.52 server 184.108.40.206
Add a hook at
/etc/dhcpcd.exit-hook (on the Pi):
#!/bin/bash if $if_up; then # Don't wait for this to finish systemctl start openntpd.service & elif $if_down; then systemctl stop openntpd.service fi