sudo mkdir /etc/certs
sudo cp radius.pem  /etc/certs/

ctrl_interface=/var/run/wpa_supplicant
network={
  ssid="MySSID"
  scan_ssid=1
  key_mgmt=WPA-EAP
  pairwise=CCMP TKIP
  group=CCMP TKIP
  eap=PEAP
  identity="raspi"
  password="mypassword"
  ca_cert="/etc/certs/radius.pem"
  phase1="peapver=0"
  phase2="MSCHAPV2"
  }

iface lo inet loopback
iface eth0 inet dhcp

allow-hotplug wlan0

iface wlan0 inet dhcp
    pre-up wpa_supplicant -B -Dwext -i wlan0 -c/etc/wpa_supplicant/wpa_supplicant.conf
    post-down killall -q wpa_supplicant