rngd

RNGD(8)								      RNGD(8)



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


SYNOPSIS
       rngd [-b, --background] [-f, --foreground] [-o,	--random-device=file]
       [-r,  --rng-device=file]	 [-s,  --random-step=nnn]  [-W, --fill-water-
       mark=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 fork-
       ing  on	startup.   This	 is  typically used for debugging.  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  --ran-
       dom-device  options  can be used to select an alternate entropy output
       device, besides the default /dev/random.	 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/ran-
	      dom)

       -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 - jgarzik@pobox.com
       Matt Sottek




rng-tools 2			  March 2001			      RNGD(8)