The disclosure relates to a method and apparatus for detecting and blocking unauthorized MAC addresses used by virtual machines. One or more data-bearing channels are coupled to an optical fiber. The approach includes recording, by a computing device, a portion of a conversation of the subscriber that occurs in a call between a first telephone and a second telephone. The method further comprises forming a passive device on the substrate at a location laterally adjacent to the interconnect section. The nozzle tube is connected to a fuel feed line for feeding a fuel to the nozzle tube, wherein the fuel is fed from the nozzle outlet opening to an annular air stream surrounding the fuel nozzle, wherein a first nozzle tube section that extends up to the nozzle outlet opening is designed in a floral pattern in such a way that the fuel may be fed substantially coaxially into the air stream.