A computing device includes a computing system and a method for identifying files transmitted from an internal computing device within an internal network to an external computing device within an external network. The computing system comprises one or more internal computing devices which are connectable by an internal network. At least one of the internal computing devices is configured to be operable as a workstation or as a file server, wherein the workstation or the file server is capable of generating, storing and/or transmitting a data file. Further, at least one of the internal computing devices is configured to be operable as an insertion device. The insertion device is capable of inserting a data file element into the data file to generate a tagged data file. Further, at least one of the internal computing devices is configured to be operable as a gateway. The gateway is capable of connecting the internal network to an external network. Further, at least one computing device is configured to be operable as a monitoring server. The monitoring server is capable of receiving information transmitted by an external computing device connected to the external network upon opening, reading and/or processing the tagged data file.