The present invention is a method of cleaning a substrate, comprising cleaning at least one surface of a substrate located in a liquid by injecting pressurized cleaning liquid containing bubbles or cleaning particles from a injection nozzle to at least one surface of the substrate. The powder particles have a particle size of 5 to 30 m. By providing a network interface that does not translate the source service address, this gateway enables the initiation and maintenance of secure, encrypted transmissions using IPSec protocol between a local area network using local IP addresses and servers on the internet.