Recommended wireless adapters

One of the most stable and affordable chipsets is Realtek RT8191, which works with the 802.11n standard. It is also compatible with the older 802.11b/g specifications, just in case your router does not support the newer 802.11n specification. However, it does not support 5 GHz frequencies or the 40 MHz dual band.

Shop around to find the best price, and it's best to not go for overpriced adapters that claim to be the only and the best ones for your Raspberry Pi.

Setting up from a desktop

Using the Wi-Fi configuration tool found in the menu bar while you're on the desktop is the most convenient way to connect to your wireless within seconds. It is recommended that you start with this if you have just installed Raspbian and plan on using Wi-Fi instead of an Ethernet connection. Your SSID, which is the readable name of your wireless access point, has to be broadcasted by your router for this to work. If you have it hidden, you should use the console method instead. Follow these steps to set up a desktop:

Setting up from a console

If you plan to run your Raspberry Pi in headless mode (where you do not have a monitor or the keyboard connected), you do not need to access the desktop by default, and you also cannot use the desktop network utility.

In the latest distributions of Raspbian, the SSH service is enabled by default, and you can SSH into your Raspberry Pi. If you have just joined your Wi-Fi network, you can tweak its settings. This is intended when you use Ethernet in order to set up the Wi-Fi. You can now log in via the SSH, and enter the following command:

sudo nano /etc/network/interfaces

This will open the included file editor, called nano, and present you with your current interface configuration. We are interested in the last few lines. If you do not see some of the lines, you can type them in manually:

auto lo
 
iface lo inet loopback
iface eth0 inet dhcp
 
allow-hotplug wlan0
auto wlan0
 
iface wlan0 inet dhcp
        wpa-ssid "ssid"
        wpa-psk "yourpassword"

To save the file, press CTRL + X, followed by Y, and finish by pressing Enter.

The allow-hotplug command will do as its name suggests: it allows you to plug wireless adapters in and out assigned to the wlan0 interface. Auto wlan0 tells Raspbian to configure the interface automatically based on the settings you provide.

We need to replace SSID and the password with the details of your router, keeping the text enclosed within quotation marks. This is the most basic configuration that can be used.

There is one problem with this configuration, though: if the wireless disconnects from your router, the interface will not be brought back up automatically. There are many scripts that try to solve this problem. The configuration requires that you know extra details about the wireless configuration. The next section offers a fully automatic way to do this. We will use wpa-supplicant, which is now installed by default with Raspbian. In /etc/network/interfaces, we change the last few lines to the following:

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

We need to go to the /etc/wpa_supplicant directory, create the file, and edit wpa_supplicant.conf:

sudo touch wpa_supplication.conf 
nano wpa_supplication.conf

In nano, a simple text editor, we need to type the following:

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

network={
 ssid="ssid"
 proto=WPA RSN
 key_mgmt=WPA-PSK
 pairwise=CCMP TKIP
 group=CCMP TKIP
 psk="password"
}

The configuration file contains some extra details about the connection. The way the supplicant works is that it will try to connect using the defined parameters for proto, pairwise, and group. You might have to adjust key_mgnt, but WPA-PSK is the most common configuration for modern wireless routers.

This method will also allow you to connect to your router if it does not broadcast its SSID.

Using wicd-curses

Using the wicd-curses package is a simpler way of setting up wireless and even wired interfaces in the console. The package allows you to edit advanced options such as a static IP, DNS, and hostnames. A daemon also runs in the background, which automatically reconnects the interface if the wireless signal drops out and is a more reliable way of maintaining a wireless network in poor signal areas. To use this package, you should comment out any settings in the wpa_supplicant interfaces file:

sudo apt-get install wicd-curses
sudo wicd-curses

You will get a console screen with a list of available wireless access points. Use the cursor keys to select your access point, and press the right arrow key to edit its properties.

Once you are in the configuring preferences screen for wireless networks, you would only need to enter your password in the key field. Save the settings by pressing F10.

If you set up the wireless connection using a wired connection, you will need to press C, which will connect to the access point. Keep an eye on the status LED on your Wi-Fi (if it has one). You should see it start to flicker, and after a few seconds, it should become solid, which means a connection has been established. At this point, it is highly likely that the SSH session will be dropped because the wired connection gets disabled. You should unplug the wired connection and reconnect using the wireless IP or hostname.