Try commentedout : #ifconfig $DEVICE up >/dev/null 2>&1 ; pump -i $DEVICE >/dev/null 2>&1 &

or try create script like this:

#!/bin/sh
ifconfig eth0 down
ifconfig eth1 down
ifconfig eth2 down
/etc/init.d/networking stop
ifconfig eth2 up
/etc/init.d/networking start

**only add eth0 and eth1 if you don't want to use it.
name it to what ever you wan't ex: mynet.sh and save it in /etc/init.d
and run update-rc.d mynet.sh defaults so it can run on boot. To remove , run update-rc.d -f mynet.sh remove .