An apparatus for offloading network, block and file functions from an operating system comprises a network interface coupled to a network for receiving packet flows; one or more processors each having one or more processor cores; a computer-readable medium carrying one or more operating systems and an input/output networking stack which are hosted in one or more of the processor cores. The networking stack is shared among the operating systems. The networking stack comprises instructions which when executed cause receiving a request for data transfer from one of the operating systems at internal network, block and file system interfaces, and permitting data to be transferred between the internal interfaces and a plurality of external interfaces by preventing the operating systems from performing the data transfer and performing the data transfer on behalf of the operating systems.