How to setup a wifi USB device on the raspberry pi


To connect my raspberry pi to a wifi network I am using a wifi USB device with a RTL8188CUS chipset. This is how I managed to connect that device to my raspberry pi which is equipped with a preloaded raspbmc image.

Normally the configuration of the wifi USB device should be very easy using the XBMC settings menu, but actually I didn’t want to make usage of the XBMC application at all. I just wanted to connect via ssh to the raspberry device without making usage of the graphical environment.

At first I had to deactivate NetworkManager as I want to configure the network settings manually from the commandline. Using NetworkManager concurrently to my manual configuration lead me to weird problems trying to bring up the wifi connection properly. Probably this is only necessary when using raspbmc. But not sure at all. At least it solved the mentioned problems I experienced.

You have to ensure to have the following packages installed on the raspberry to be able to configure the USB device as described below.

sudo apt-get install wireless-tools wpasupplicant usbutils

Install the necessary driver

To find out which chipset is implemented on the USB device I used lsusb which pointed to the mentioned chipset as mentioned earlier.

pi@raspbmc:~$ lsusb
Bus 001 Device 002: ID 0424:9514 Standard Microsystems Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp.
Bus 001 Device 004: ID 0bda:8176 Realtek Semiconductor Corp. RTL8188CUS 802.11n WLAN Adapter

The last entry of that list indicates the USB device I had plugged to my raspberry. This information is relevant to find out the valid driver package to run properly the device. You will find the respective package with the needed firmware searching for the pattern ‚Realtek‘.

pi@raspbmc:~$ sudo apt-cache search Realtek
firmware-realtek - Binary firmware for Realtek wired and wireless network adapters

Actually on my raspbmc this packages was already installed, which I figured out when I tried to install the package.

pi@raspbmc:~$ sudo apt-get install firmware-realtek
Reading package lists... Done
Building dependency tree
Reading state information... Done
firmware-realtek is already the newest version.
0 upgraded, 0 newly installed, 0 to remove and 10 not upgraded. 

Setup the wifi connection

Now it should be possible to scan the wifi access points in range. The access point which should be connected to the raspberry should be listed as well. My access point is named CONNECTBOX. The other access points listed belong to my neighbors which are also in range.

pi@raspbmc:/$ iwlist wlan0 scan | grep ESSID

The specific network, which should be connected to the raspberry device, has to be defined in the configuration file /etc/network/interfaces in the following manner. The loopback and eth0 adapter should be defined there as well.

pi@raspbmc:/$ sudo cat /etc/network/interfaces
auto lo
iface lo inet loopback

iface eth0 inet dhcp
iface default inet dhcp

auto wlan0
iface wlan0 inet dhcp
wpa-ssid "CONNECTBOX"
wpa-psk "mypassword"  

At this point an unencrypted password has been inserted for the respective adapter configuration. I would absolutely recommend to insert an encrypted password just for security reasons. An encrypted version of the password can be determined with the wpa_passphrase tool, passing the SSID name and the respective password as follows.

pi@raspbmc:/$ wpa_passphrase CONNECTBOX mypassword

You have to insert the value of the attribute psk to the /etc/network/interfaces configuration file, replacing the unencrypted value for wpa-psk.

pi@raspbmc:/$ sudo cat /etc/network/interfaces
auto lo
iface lo inet loopback

iface eth0 inet dhcp
iface default inet dhcp

auto wlan0
iface wlan0 inet dhcp
wpa-ssid "CONNECTBOX"
wpa-psk c41176098137e80eff03391079f29f9c5f43d4aab7da39bb7ab56b13ced6b413

Please note the missing quote marks for the encrypted password!

The first start of the wifi connection can be started with the command ifup

pi@raspbmc:~$ sudo ifup wlan0
ioctl[SIOCSIWAP]: Operation not permitted
ioctl[SIOCSIWENCODEEXT]: Invalid argument
ioctl[SIOCSIWENCODEEXT]: Invalid argument
Internet Systems Consortium DHCP Client 4.2.2
Copyright 2004-2011 Internet Systems Consortium.
All rights reserved.
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Listening on LPF/wlan0/00:11:c1:19:ad:5c
Sending on   LPF/wlan0/00:11:c1:19:ad:5c
Sending on   Socket/fallback
DHCPDISCOVER on wlan0 to port 67 interval 7
DHCPDISCOVER on wlan0 to port 67 interval 8
DHCPREQUEST on wlan0 to port 67
Reloading /etc/samba/smb.conf: smbd only.
bound to -- renewal in 516632 seconds.

From now on the wifi connection is being established with each start of the raspberry device.