tunnel () {
	machine="$1"
	port_local="$2"
	port_remote="$2"
	if [ ! -z "$3" ]
	then
		port_remote="$3"
	fi
	echo "ssh $machine -N -L \"${port_local}:localhost:${port_remote}\""
	ssh $machine -N -L "${port_local}:localhost:${port_remote}"
}

# Now you may:
# tunnel MyServer 8001 4001
# tunnel MyServer 27017