Fuente: Wipo "IOT" A collection unit (15a) collects: information about IoT devices connected to IoT gateways; and whitelists that indicate the content of communication permitted for each IoT device, the whitelists being stored in the IoT gateways. A calculation unit (15b) calculates: a feature amount indicating a feature of communication of the IoT devices for each IoT gateway, on the basis of the collected IoT device information; and the degree of similarity of the feature amounts among the IoT gateways. When the calculated degree of similarity is equal to or greater than a prescribed threshold value, an extraction unit (15c) extracts, from the whitelist information for the IoT devices included in the whitelists stored in the IoT gateways, whitelist information for the IoT devices that mutually supplements the whitelists. A joining unit (15d) joins the extracted whitelist information and the whitelists stored in the IoT gateways.