🛠 WiFi sur la prise USB unique et SSH à distance

Objectives

• Make the Model A network-capable: it has no built-in Ethernet or WiFi, only a direct USB 2.0 port on the BCM2835.
• Configure wpa_supplicant in station mode and obtain an address via DHCP.
• Connect via SSH from a laptop, then operate without a screen and keyboard.

Hardware

• An old-stock USB WiFi dongle (driver included in the legacy image) or, as a dongle-free alternative, a g_ether gadget setup connected to the laptop.
• A quality power supply: some dongles exceed the single port's power budget and blow the polyfuse.
• An empty ssh file on the boot partition to enable the SSH server on first boot.

Complete code

# /etc/wpa_supplicant/wpa_supplicant.conf
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
country=FR
network={
    ssid="MonReseau"
    psk="MotDePasseWiFi"
}

# Appliquer
sudo wpa_cli -i wlan0 reconfigure
sudo dhclient wlan0
ip -4 addr show wlan0

# Depuis le portable (le Model A n'a pas de MAC fixe en gadget, se fier au nom mDNS)
ssh pi@raspberrypi.local

Expected verification

ip -4 addr show wlan0 displays an address in the 192.168.x.x range; pinging the router works; the SSH session opens without a screen or keyboard connected to the Pi. >

Common errors

• Dongle drawing too much power: disconnections, brown-outs, throttling — try a powered hub.
• In g_ether gadget mode, the MAC address seen by the laptop changes on each connection (known firmware bug #843): rely on raspberrypi.local.
• WiFi password with accents or country not set: association fails.
• Forgetting country=FR: channels 12-13 unavailable, network not found.