The apparatus comprises a plurality of interfaces, each interface having an associated interface ID; and a hardware-side processing device including at least one programmable hardware-implemented chip configured to process request packets, which are received from host computers and relate to access requests to one or more file system managed by the apparatus, and to generate response packets for the processed request packets; wherein, for a request packet which is received from a first host computer, at least one programmable hardware-implemented chip is configured to: determine the client ID being associated with the first host computer, determine the interface ID being associated with the first interface, determine whether the determined client ID and interface ID represent a permitted ID set or a prohibited ID set, and refrain from processing the received request packet if the determined client ID and interface ID represent a prohibited ID set.