A network system has a first LAN, a second LAN, and a storage device for storing
data accessible from the first LAN and the second LAN. A control apparatus controls
accessibility of the data stored in the storage device from the first LAN and the
second LAN. The control apparatus includes an access prevention device for preventing
access from the first LAN to the second LAN and from the second LAN to the first
LAN and a device for overriding a setting of the access prevention device to allow
accessibility of the second LAN from the first LAN.