IN-VEHICLE EQUIPMENT, VEHICLE, AND METHOD

An in-vehicle equipment includes: a signal detection unit configured to detect a signal expected to be input to a communication network at a predetermined input cycle; a counting unit configured to count the number of times a signal is detected by the signal detection unit; and a determination unit configured to determine whether the number of times counted by the counting unit within a predetermined first period is equal to or less than a threshold value set between a first value calculated by dividing the first period by the input cycle and a second value calculated on the basis of the first period and the input cycle on assumption that an illegal signal is further input to the communication network.