Why not make network interfaces actual files in /dev? The relevant system calls could be replaced with library calls that access the files, in order to maintain compatibility with POSIX... No? Would it be possible to implement finer grained access control for X11, DAC-style? Like e.g. in Plan 9: - Every window would be represented by a file - Every file in question would have the usual set of DAC permissions - Window permissions could be used to facilitate sharing a desktop between users without giving either user full access Related: how much of traditional UNIX could be emulated on a Plan 9 based OS?