A method of embossing a crown cap comprises the steps of: detecting a pre-printed drawing on the bottom of the crown cap, varying the angular positioning of the crown cap so as to position the drawing according to a preset positioning, and impressing a raisedrecessed pictogram on the bottom of the crown cap. Traditional packet filtering techniques to protect against malicious packets designed to exploit defects in applications, based on external packet filtering devices create a bottleneck in network traffic and present a large overhead cost. A pair of pivot pins is formed on opposite lateral sides of the body respectively, and a pair of pivot holes is defined in opposite lateral sides of the top lid respectively.