Air gap (networking)

An air gap, air wall, air gapping^[1] or disconnected network is a network security measure employed on one or more computers to ensure that a secure computer network is physically isolated from unsecured networks, such as the public Internet or an unsecured local area network.^[2] It means a computer or network has no network interface controllers connected to other networks,^[3][4] with a physical or conceptual air gap, analogous to the air gap used in plumbing to maintain water quality.