cat /etc/network/interfaces

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet dhcp

auto wlan0
iface wlan0 inet dhcp
pre-up /sbin/ifconfig wlan0 up
pre-up /sbin/iwconfig wlan0 mode managed
pre-up /sbin/iwconfig wlan0 essid linux-linksys
pre-up /sbin/iwpriv wlan0 set AuthMode=WPAPSK
pre-up /sbin/iwpriv wlan0 set EncrypType=AES
pre-up /sbin/iwpriv wlan0 set WPAPSK=dummy