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RNGD(8)								       RNGD(8)

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

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

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 auto‐
       matically, 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

       -i, --ignorefail
	      Ignore repeated fips failures

       -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/hwran‐
	      dom)

       -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)

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