I was configuring my Raspberry Pi (B+) on Raspbian via the ethernet port, but also wanted to get the WiFi adapter up and running. I had some issues getting both running at the same time though – don’t know why as the device is running headless, but as soon as I disconnected the ethernet cable the WiFi was working as you would expect.
The workaround for this is a little messy, but I thought I’d share it here. First of all, use either the GUI or the config file to configure the WiFi (GUI is easier). The key point here, as I want to use a static IP when on my home network and DHCP the rest of the time, is to set the ‘id_str’ parameter to something meaningful e.g. home_network. The id_str allows us to match a WiFi access point to an interface configuration.
WiFi Config File
This is stored in /etc/wpa_supplicant/wpa_supplicant.conf
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
network={
ssid="network-SSID"
psk="my_network_key"
proto=RSN
key_mgmt=WPA-PSK
pairwise=TKIP
auth_alg=OPEN
id_str="<strong>home_static</strong>"
}
Interfaces File
This is /etc/network/interfaces
Note how the iface name is the same as the id_str for the home network/static IP configuration
auto lo iface lo inet loopback allow-hotplug eth0 iface eth0 inet dhcp allow-hotplug wlan0 iface wlan0 inet manual wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf iface <strong>home_static</strong> inet static address 192.168.1.20 netmask 255.255.255.0 gateway 192.168.1.1 iface default inet dhcp
The Weirdness
For some reason if we hotplug the Ethernet port we disable wlan0 (and it makes a right mess of things as the sshd and other services aren’t bound to the correct interface any more).
So we edit /etc/default/ifplugd
INTERFACES="eth0" HOTPLUG_INTERFACES="eth0" ARGS="-q -f -u0 -d10 -w -I" SUSPEND_ACTION="stop"
And to give the WiFi dongle a kick at startup we add the following to /etc/rc.local.
# Disable the ifplugd eth0 sudo ifplugd eth0 --kill sudo ifup wlan0
