Tech Blog (wh)

Recently I wanted to set up Wireless (Wi Fi) Ethernet 802.1X authentication on a Raspberry Pi with Raspbian “wheezy” 3.6 (version 3.6.11 actually) and the Edimax EW 7811UN WiFi Adapter.

I had read a lot of posts about having trouble with the Edimax adapter – and how you would need to replace the driver file `cfg80211.ko` and / or rebuild one from the source code. This simply wasn’t true for me – the device worked very well right out of the box – with a few small configuration changes which I will share with you.

Here is my setup:

– Raspberry Pi was a “Pi Model B” with the 512MB of memory
– Downloaded Raspbian wheezy from the [downloads site](http://www.raspberrypi.org/downloads) – version was `2013-05-25-wheezy-raspbian.zip1
– Created a SD card with the image
– EW-7811UN WiFi Adapter

Notes:

– If you boot up the Pi and then plug in the EW-7811UN WiFi Adapter directly to the Pi, it will likely crash / reboot the Pi. This is not a problem with either device, but the `EW-7811UN WiFi Adapter` requires a lot of power and so it underloads the Raspberry Pi’s circuits and causes this behavior.
– If you have a powered USB hub (in my case my monitor) and plug / unplug the `EW-7811UN WiFi Adapter` then you will not cause the system to crash / reboot
– I did my initial bootup of the Pi without the `EW-7811UN WiFi Adapter` plugged in
– I did not select any special options on the first boot – I just went down and hit the “continue” button
– After rebooting, I logged in as `pi` and the command propt started but no GUI (this is expected behavior) and the `EW-7811UN WiFi Adapter` was still not plugged in
– Next I plugged in the `EW-7811UN WiFi Adapter` into the monitor (powered usb hub) and the ran `lsusb` and `iwconfig` which both showed the `EW-7811UN WiFi Adapter` available. You can also use `lsmod` to get information on the chipset of your devices.
– The `EW-7811UN WiFi Adapter` should show up as `wlan0` – the third of three devices (wired, loopback, and wifi)

There are some options for the network configuration in this file, but **you should not need to edit this file**:

/etc/network/interfaces

The final line of that file, however, should be something like this (should already be existing):

wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf

That of course points to a file that you will need to configure:

/etc/wpa_supplicant/wpa_supplicant.conf

If you don’t know how to do that, use a command to edit using either `emacs` or `vi` and you will need to preface this with `sudo`:

sudo vi /etc/wpa_supplicant/wpa_supplicant.conf

If you are using `WPA-PSK` (not 802.1X) you can add something like this to the bottom of that file (don’t delete what is already there – just APPEND it):

network={
ssid=”_SSID_”
proto=RSN
key_mgmt=WPA-PSK
pairwise=CCMP TKIP
group=CCMP TKIP
psk=”_WPA_SHARED_KEY_”
}

Replace `_SSID_` and `_WPA_SHARED_KEY_` with the correct corresponding values.

Now for the good stuff – industrial `802.1X` or `802.1X LEAP` authentication – yay! Instead of appending that last block, use something like this:

network={
ssid=”_SSID_”
scan_ssid=1
key_mgmt=WPA-EAP
eap=PEAP
pairwise=CCMP TKIP
group=CCMP TKIP
# authentification info
identity=”_USERNAME_”
password=”_PASSWORD_”
phase1=”peaplabel=0″
phase1=”auth=MSCHAPV2″
}

Again, be sure to replace `_SSID_`, `_USERNAME_`, and `_PASSWORD_` with the correct values.

Now save the file, and reboot your `pi` and then run `ifconfig` and the `wlan0` should now have a real IP address and be connected to the network! Yay!

More notes:

– When I rebooted the first time this worked – but then I unplugged the ethernet cable, and although the wireless network was connected, the `pi` was still defaulting to the wired connection `eth0` and so I had to reboot again after unplugging the wired connection – but upon reboot the `pi` was functioning with wireless with NO PROBLEMS with the `Edimax EW-7811UN WiFi Adapter` – woot woot!
– Update: I left the pi turned off overnight and when I turned it on again it didn’t connect to the wireless. Running lsusb showed that the adapter was not available. I unplugged the adapter, rebooted, then inserted the adapter after it was booted up. The adapter showed up. After rebooting once again it connected to the WiFi automatically. There are probably some commands to facilitate connecting automatically after a period of the pi being off but I haven’t discovered yet.