Roaming dhcp

src/freedombone-utils-wifi

     echo "allow-hotplug ${WIFI_INTERFACE}" >> /etc/network/interfaces
     echo "iface ${WIFI_INTERFACE} inet manual" >> /etc/network/interfaces
     echo "  wpa-roam $WIFI_CONFIG" >> /etc/network/interfaces
+    echo '' >> /etc/network/interfaces
+    echo '#this line must always be here' >> /etc/network/interfaces
+    echo 'iface default inet dhcp' >> /etc/network/interfaces
 
     wpa_passphrase "$ssid" "$passphrase" > $WIFI_CONFIG
 
     echo "allow-hotplug ${WIFI_INTERFACE}" >> /etc/network/interfaces
     echo "iface ${WIFI_INTERFACE} inet manual" >> /etc/network/interfaces
     echo "  wpa-roam $WIFI_CONFIG" >> /etc/network/interfaces
+    echo '' >> /etc/network/interfaces
+    echo '#this line must always be here' >> /etc/network/interfaces
+    echo 'iface default inet dhcp' >> /etc/network/interfaces
 
     echo 'update_config=1' > $WIFI_CONFIG
     echo 'eapol_version=1' >> $WIFI_CONFIG
     echo "allow-hotplug ${WIFI_INTERFACE}" >> /etc/network/interfaces
     echo "iface ${WIFI_INTERFACE} inet manual" >> /etc/network/interfaces
     echo "  wpa-roam $WIFI_CONFIG" >> /etc/network/interfaces
+    echo '' >> /etc/network/interfaces
+    echo '#this line must always be here' >> /etc/network/interfaces
+    echo 'iface default inet dhcp' >> /etc/network/interfaces
 
     # remove wpa_supplicant.conf if it exists
     if [ -f $WIFI_CONFIG ]; then