A system includes a detection unit configured to detect unauthorized access to one or more information processing apparatuses that are virtually implemented by virtual machines executed by a computer; an authorized network configured to transfer authorized access to the one or more information processing apparatuses from an external network; a honeypot network configured to transfer unauthorized access to the information processing apparatuses from the external network; and a control unit configured to connect the information processing apparatuses for which no unauthorized access has been detected to the authorized network, and connect the information processing apparatuses for which unauthorized access has been detected to the honeypot network; wherein the control unit shifts, in response to detecting unauthorized access by the detection unit, the corresponding information processing apparatus into a decoy mode in which the detected unauthorized access is disconnected from a normal operation.