How do I configure a USB WiFi Dongle from the command line?

Question

I have a Pi, and with a fresh install, I can configure wifi connectivity using a helpful tool in X windows nicely.

However, what are the command line tools for configuring WiFi? What configuration files are updated?

This isn't critical, but I'd like to know.

Answer 1

Do this, assuming the standard WPA2 necured network:

sudo nano /etc/wpa_supplicant/wpa_supplicant.conf

Enter this text, replacing the details with yours (id_str is just a comment, you can leave it as-is):

network={
    ssid="TheGarNetwork"
    psk="lollzthisisanexcellentpssword"
    proto=RSN
    key_mgmt=WPA-PSK
    pairwise=CCMP
    auth_alg=OPEN
    id_str="Home_Wi-Fi"
}

CTRL-X, then press Y, then press Enter to save.

Next, type:

sudo nano /etc/network/interfaces

and add this to it:

allow-hotplug wlan0
auto wlan0
iface wlan0 inet manual
wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf


iface default inet static
    address 192.168.1.128
    netmask 255.255.255.0
    gateway 192.168.1.1

(allow-hotplug is optional, if you're likely to be unplugging and replugging the adapter, and don't want to have to manually reconnect.)
Fill in the IPs with the appropriate details, or (if you don't want to deal with that,) just replace the word "static" with "dhcp" and delete everything after it.

When you've got that done, reboot and see what happens!

Answer 2

If you edit /etc/network/interfaces and add these lines :

pre-up wpa_supplicant -B w -D wext -i wlan0 -c /etc/wpa_supplicant/wpa_supplicant.conf
post-down killall -q wpa_supplicant

You can then "connect" to your network simply by typing

ifup wlan0

..And disconnect

ifdown wlan0

Saves the user from having to reboot the machine..

Here is where I took it from.. Source