A control device includes: a physical first communication port that connects to a first network—to which an information processing device belongs; a physical second communication port that connects to a second network to which the drive device belongs; and a storage device that stores a user program created for controlling the drive device. The user program includes a filtering function for switching a filtering condition in accordance with a setting for the filtering condition that is input during execution of the user program. The filtering condition is used for determining whether or not to transmit communication data received from one device to another device. The one device is one of the drive device and the information processing device. The other device is the other of the drive device and the information processing device.