RNGD(8)                                                                                                                  RNGD(8)



NAME
       rngd - Check and feed random data from hardware device to kernel random device


SYNOPSIS
       rngd  [-b,  --background]  [-f,  --foreground] [-o, --random-device=file] [-r, --rng-device=file] [-s, --random-step=nnn]
       [-W, --fill-watermark=nnn] [-t, --timeout=nnn] [-?, --help] [-V, --version]


DESCRIPTION
       This daemon feeds data from a random number generator to the kernel's random number entropy pool,  after  first  checking
       the data to ensure that it is properly random.

       The  -f  or --foreground options can be used to tell rngd to avoid forking on startup.  This is typically used for debug-
       ging.  The -f or --foreground options, which fork and put rngd into the background automatically, are the default.

       The -r or --rng-device options can be used to select an alternate source of input,  besides  the  default  /dev/hwrandom.
       The -o or --random-device options can be used to select an alternate entropy output device, besides the default /dev/ran-
       dom.  Note that this device must support the Linux kernel /dev/random ioctl API.

       FIXME: document random-step and timeout


OPTIONS
       -b, --background
              Become a daemon (default)

       -f, --foreground
              Do not fork and become a daemon

       -o file, --random-device=file
              Kernel device used for random number output (default: /dev/random)

       -r file, --rng-device=file
              Kernel device used for random number input (default: /dev/hwrandom)

       -s nnn, --random-step=nnn
              Number of bytes written to random-device at a time (default: 64)

       -W n, --fill-watermark=nnn
              Once we start doing it, feed entropy to random-device until at least fill-watermark bits of entropy are  available
              in  its  entropy  pool  (default:  2048).   Setting  this too high will cause rngd to dominate the contents of the
              entropy pool.  Low values will hurt system performance during entropy starves.  Do not  set  fill-watermark  above
              the size of the entropy pool (usually 4096 bits).

       -t nnn, --timeout=nnn
              Interval written to random-device when the entropy pool is full, in seconds, or 0 to disable (default: 60)

       -?, --help
              Give a short summary of all program options.

       -V, --version
              Print program version


AUTHORS
       Philipp Rumpf
       Jeff Garzik - jgarzikATpobox.com
       Matt Sottek




rng-tools 3                                                March 2001                                                    RNGD(8)