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By default the Raspberry Pi uses DHCP to configure its network interfaces, including, on the model B, the built-in ethernet port. In this post I’ll cover how you can set up your Raspberry Pi to automatically connect to your wireless network and obtain a static IP or configure WPA2 using wpa_supplicant. All you need is a WiFi dongle.

SETUP THE WIFI INTERFACE

I have a new “ASUS USB-N10” 802.11b/g/n USB WiFi dongle with the chip “Realtek 8192cu” (used in many adapters). This dongle needs the firmware-realtek package which is preinstalled in the newer Rasbian releases. So just need to plug it into the USB port and it will work.

Note that a WiFi dongle will probably need more power than the Raspberry Pi USB port can provide, especially if there is a large distance from the WiFi dongle to the WiFi Access Point, or it is transferring large amounts of data. Therefore, you may need to plug the WiFi dongle into a powered USB hub. But “ASUS USB-N10” is working fine.

First we’ll make sure the dongle is recognized:

lsusb

Bus 001 Device 002: ID 0424:9512 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 0b05:17ba ASUSTek Computer, Inc.

As you can see, my ASUS dongle is on the last line.

Now run lsmod to see avaliable kernel modules, hopefully we’ll see something that matches our chip:

lsmod

Module Size Used by
snd_bcm2835 21342 0
snd_pcm 93100 1 snd_bcm2835
snd_seq 61097 0
snd_seq_device 7209 1 snd_seq
snd_timer 23007 2 snd_pcm,snd_seq
snd 67211 5 snd_bcm2835,snd_timer,snd_pcm,snd_seq,snd_seq_device
8192cu 569585 0
uio_pdrv_genirq 3666 0
uio 9897 1 uio_pdrv_genirq

The interesting module is third last (8192cu).

Now do a WiFi scan to see working it or no:

iwlist wlan0 scan

Note: Your Wi-Fi dongle may have a name wlan1 instead of wlan0.

SETUP THE WIFI NETWORK

First need is add a network configuration to the file /etc/wpa_supplicant/wpa_supplicant.conf.

Open up the /etc/wpa_supplicant/wpa_supplicant.conf file:

sudo nano /etc/wpa_supplicant/wpa_supplicant.conf

Edit it so that, it will look like this:

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1

network={
     ssid="Your SSID Here"
     psk="Enter Passkey Here"
     proto=RSN
     key_mgmt=WPA-PSK
     pairwise=CCMP TKIP
     group=CCMP TKIP
}

or, if you use more then one network configuration, it will look like this:

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1

network={
     ssid="Your SSID Here"
     psk="Enter Passkey Here"
     proto=RSN
     key_mgmt=WPA-PSK
     pairwise=CCMP TKIP
     group=CCMP TKIP
     id_str="home"
     priority=1
}

network={
     ssid="Your SSID Here"
     psk="Enter Passkey Here"
     proto=RSN
     key_mgmt=WPA-PSK
     pairwise=CCMP TKIP
     group=CCMP TKIP
     id_str="work"
     priority=2
}
  • said - name of SSID
  • psk - passkey
  • proto - could be either RSN (WPA2) or WPA (WPA1).
  • key_mgmt - could be either WPA-PSK (most probably) or WPA-EAP (enterprise networks)
  • pairwise - could be either CCMP (WPA2) or TKIP (WPA1)
  • group - could be either CCMP (WPA2) or TKIP (WPA1)
  • id_str - name of configuration
  • priority - priority of network

After you have modified the wpa_supplicant.conf file, you will need to change the wlan0 section of the /etc/network/interfaces file.

Open up the /etc/network/interfaces file:

sudo nano /etc/network/interfaces

Edit the wlan0 section so that, for a static IP, it will look like this:

## WiFi
#allow-hotplug wlan0
iface wlan0 inet manual
     wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf
iface default inet static
     address 192.168.1.2
      netmask 255.255.255.0
      network 192.168.1.0
      gateway 192.168.1.1

And for DHCP, it will look like this:

## WiFi
#allow-hotplug wlan0
iface wlan0 inet manual
     wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf
iface default inet dhcp

or if you use more then one network configuration:

## WiFi
#allow-hotplug wlan0
iface wlan0 inet manual
     wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf
iface default inet dhcp
iface home inet dhcp
iface work inet dhcp

After that, you will need to bring down the wlan0 interface and then back it up:

sudo ifdown wlan0
sudo ifup wlan0

Now you can check the wireless connection using the iwconfig command:

iwconfig

wlan0 IEEE 802.11bgn ESSID:"Your SSID Here" Nickname:"<WIFI@REALTEK>"
Mode:Managed Frequency:2.412 GHz Access Point: NN:NN:NN:NN:NN:NN
Bit Rate:150 Mb/s Sensitivity:0/0
Retry:off RTS thr:off Fragment thr:off
Power Management:off
Link Quality=98/100 Signal level=60/100 Noise level=0/100
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0

lo no wireless extensions.

eth0 no wireless extensions.

WHAT WE GET

1. During bootup, wpa_supplicant searches through each network we have listed with a specific priority in the file wpa_supplicant.conf, then chooses the first active network it finds.

2. If there is no WiFi dongle connected, it uses the wired connection eth0.

3. We can now connect to my router that have a hidden SSID (SSID not broadcasted), which was not possible with just the /etc/network file by itself without using wpa_supplicant.conf. I disable broadcasts for security reasons.

4. The wpa_supplicant file does not think that the character \ is an escape character in the password field, unlike the /etc/network file by itself without using wpa_supplicant.conf, which required that it be escaped with another escape character \\.

If this article has helped you then please leave a comment :smiley:

Thanks for reading!