Connect raspberry pi to a password protected AP (WPA2)

1. This tutorial use TL-WN725n wifi dongle attach with raspberry pi. Follow this link for driver installation.
2. Attach the TL-WN725n wifi dongle to raspberry pi. Open raspberry pi terminal, install wpa-supplicant and wireless-tools

3. Edit /etc/wpa_supplicant/wpa_supplicant.conf. For WPA2 encryption, edit as following (note: SSID and password depends on your AP):-

4. Edit /etc/network/interfaces. Make sure wireless interface is set to dhcp so it can obtain IP address from AP's DHCP server.

5. Run /etc/init.d/networking restart or reboot. Run ifconfig to make sure wireless interface got an IP address.
 

"wlan0" get an IP address from AP's DHCP server