Raspberry PI IP stup command line

Getting WiFi network details

To scan for WiFi networks, use the command sudo iwlist wlan0 scan. This will list all available WiFi networks along with other useful information. Look out for:

1. ESSID:"testing". This is the name of the WiFi network.
2. IE: IEEE 802.11i/WPA2 Version 1. This is the authentication used; in this case it is WPA2, the newer and more secure wireless standard which replaces WPA1. This guide should work for WEP, WPA or WPA2, but may not work for WPA2 enterprise.
   You will also need the password for the WiFi network. For most home routers this is located on a sticker on the back of the router. The ESSID (ssid) for the network in this case is testing and the password (psk) testingPassword.

Adding the network details to the Raspberry Pi

Open the wpa-supplicant configuration file in nano:
sudo nano /etc/wpa_supplicant/wpa_supplicant.conf
Go to the bottom of the file and add the following:

network={
    ssid="The_ESSID_from_earlier"
    psk="Your_wifi_password"
}

In the case of the example network, we would enter:

network={
    ssid="testing"
    psk="testingPassword"
}

Now save the file by pressing ctrl+x then y, then finally press enter.
At this point, wpa-supplicant will normally notice a change has occurred within a few seconds, and it will try and connect to the network. If it does not, either manually restart the interface with sudo ifdown wlan0 and sudo ifup wlan0, or reboot your Raspberry Pi with sudo reboot.
You can verify if it has successfully connected using ifconfig wlan0. If the inet addr field has an address beside it, the Pi has connected to the network. If not, check your password and ESSID are correct.