Configure WPA wireless network interface in ubuntu through command line

We will go through steps to configure wireless network interface having WPA security through command line in ubuntu

• Ensure that wpa_supplicant package is installed. If not try to get it by running
•   sudo apt-get install wpasupplicant
• Open your /etc/networking/interfaces (with sudo) file and add below two lines

auto wlan0

iface wlan0 inet dhcp

• reboot the system (Dont worry if the startup says all network are not started. We will set it up)
• Now type "wpa_supplicant -h" to get list of driver names. Observe the section "drivers:" in the output. Watch out for driver text like "Linux Wireless extension". Generally it is wext
• Now we will create a configuration file for wpa. Create one in /etc/wpa_supplicant.conf with below content

ctrl_interface=/var/run/wpa_supplicant

eapol_version=1

ap_scan=1

fast_reauth=1

• Now we will generate the text required for the WPA authentication. Type below command where NetworkSSID is your wireless network name
• wpa_passphrase "NetworkSSID"
• Enter your WPA passphrase when it prompts
• Now it will generate a ouput similar to below

network={

ssid="NetworkSSID"

#psk="YOUR_PSK"

psk=lklksdjflwejroi209429083lkdfjlskdfjslkdfjlk

}

• Copy the above text to the end of /etc/wpa_supplicant.conf and also add scan_ssid, proto & key_mgmt keys as below (#psk can be removed as it's just a comment)

network={

ssid="NetworkSSID"

scan_ssid=1

prot=WPAi

key_mgmt=WPA-PSK

psk=lklksdjflwejroi209429083lkdfjlskdfjslkdfjlk

}

• Now type below command to test all the configurations done till now. In below command wlan0 is the  interface name we defined in /etc/networking/interfaces and wext is your wireless driver name
•   sudo wpa_supplicant -iwlan0 -c/etc/wpa_supplicant.conf -Dwext
• You should see below text in output
•  WPA: Key negotiation completed with 
• The above output confirms that all steps are correct till now
• Now we just need to tell ubuntu to use this wpa_supplicant configuration for this particular wireless device. For that, add two lines in /etc/networking/interfaces immediately after (iface wlan0 inet dhc) line which we added in the beginning. So it would look like (combined)

auto wlan0

iface wlan0 inet dhcp

wpa-driver wext

wpa-conf /etc/wpa_supplicant.conf

• Reboot the system

That's it. Now you should be able to access wifi from your ubuntu machine