1. A network appliance, comprising: a processor, which is configured to execute storage commands in one or more storage devices; and a Host Bus Adapter (HBA), which is coupled to a network so as to receive communication frames sent over the network to the network appliance, and is configured to filter the received communication frames so as to pass through to the processor only a subset of the received communication frames, which correspond to the storage commands that have been sent by one or more applications for processing by the network appliance.