Raspberry Pi wireless Network
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Raspberry Pi wireless Network

This method is suitable if you don’t have access to the graphical user interface normally used to set up WiFi on the Raspberry Pi. It is particularly suitable for use with a serial console cable if you don’t have access to a screen or wired Ethernet network. Note also that no additional software is required; everything you need is already included on the Raspberry Pi.

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”‘ is the name of the WiFi network.
  2. ‘IE: IEEE 802.11i/WPA2 Version 1’ is the authentication used. In this case it’s WPA2, the newer and more secure wireless standard which replaces WPA. This guide should work for WPA or WPA2, but may not work for WPA2 enterprise. For WEP hex keys, see the last example here. You’ll also need the password for the wireless network. For most home routers, this is found on a sticker on the back of the router. The ESSID (ssid) for the examples below is testing and the password (psk) is 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=”testing” psk=”testingPassword” }

The password can be configured either as the ASCII representation, in quotes as per the example above, or as a pre-encrypted 32 byte hexadecimal number. You can use the wpa_passphrase utility to generate an encrypted PSK. This takes the SSID and the password, and generates the encrypted PSK. With the example from above, you can generate the PSK with wpa_passphrase “testing” “testingPassword. The output is as follows.

Note that the plain text version of the code is present, but commented out. You should delete this line from the final wpa_suplicant file for extra security.

The wpa_password tool requires a password with between 8 and 63 characters. For more complex passphrases you can extract the content of a text file and use it as input for wpa_passphrase, if the password is stored as plain text inside a file somewhere, by calling wpa_passphrase “testing” < file_where_password_is_stored. For extra security, you should delete the file_where_password_is_stored afterwards, so there is no plain text copy of the original password on the system.

If you are using the wpa_passphrase encrypted PSK you can either copy and paste the encrypted PSK into the wpa_supplicant.confg file, or redirect the tools output to your configuration file by calling wpa_passphrase “testing” “testingPassword” > /etc/wpa_supplicant/wpa_supplicant.conf. Note that this requires you to change to root (by executing sudo su), or you can use wpa_passphrase “testing” “testingPassword” | sudo tee -a /etc/wpa_supplicant/wpa_supplicant.conf > /dev/null, which will append the passphrase without having to change to root. Both methods provide the necessary administrative privileges to change the file. Lastly, make sure you use >, or use -a with tee, (both can be used to append text to an existing file) since , or omitting -a when using tee, will erase all contents and then append the output to the specified file. Note that the redirection to /dev/null at the end of the second form simply prevents tee from also outputting to the screen (standard output).

Now save the file by pressing Ctrl+X, then Y, then finally press Enter.

At this point, wpa-supplicant will normally notice within a few seconds that a change has occurred, and it will try and connect to the network. If it does not, restart the interface with sudo wpa_cli reconfigure.

You can verify whether it has successfully connected using ifconfig wlan0. If the inet addr field has an address beside it, the Raspberry Pi has connected to the network. If not, check that your password and ESSID are correct.

Unsecured Networks

If the network you are connecting to does not use a password, the wpa_supplicant entry for the network will need to include the correct key_mgmt entry. e.g.

network={ ssid=”testing” key_mgmt=NONE }

Hidden Networks

If you are using a hidden network, an extra option in the wpa_supplicant file, scan_ssid, may help connection.

network={ ssid=”yourHiddenSSID” scan_ssid=1 psk=”Your_wifi_password” }

You can verify whether it has successfully connected using ifconfig wlan0. If the inet addr field has an address beside it, the Raspberry Pi has connected to the network. If not, check your password and ESSID are correct.

Adding multiple wireless network configurations

On recent versions of Raspbian, it is possible to set up multiple configurations for wireless networking. For example, you could set up one for home and one for school.


Source: www.raspberrypi.org