Provided are methods and apparatuses for hardening a communication device, which methods and apparatuses make it possible to identify a use of at least one port, by which port a request is submitted to the communication device by a message, and to output a signal for blocking the at least one port if, after a specifiable time period, either the use of the port in question is detected as low or no use of the port in question is detected. Embodiments can be used to harden communication devices in a production line, in a hospital and/or in a power supply network.