The intentional passage, through a building wall or partition, or an equipment enclosure or chassis, of a signal-bearing communications medium, e.g., a cable, metallic or optical. 2. Unintended access to the information within a communications or information-processing device via a metallic path intended for another purpose, e.g., via the primary power connection. 3. The unauthorized act of bypassing the security mechanisms of a system. 4. The passage of an rf signal through a physical barrier, such as a partition, a wall, a building, or earth. 5. Unauthorized access to a data processing system.