Provided is a network cabling apparatus and protective apparatus for the protected transmission of data, comprising two protective devices which are assigned to one another and can each be connected to one end of a data transmission device, each protective device having: a first interface for connection to the data transmission apparatus; a second interface for connection to a device; and a crypto unit which has a cryptographic function that can be configured in an equivalent manner on each of the assigned protective devices and which cryptographically protects the data to be transmitted.