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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]  [-o,	 --random-device=file]
       [-p,  --pid-file=file]  [-r, --rng-device=file] [-s, --random-step=nnn]
       [-W, --fill-watermark=nnn] [-d, --no-drng=1|0] [-n, --no-tpm=1|0]  [-q,
       --quiet] [-v, --verbose] [-?, --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	-b  or
       --background 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

       -p file, --pid-file=file
	      File used for  recording	daemon	PID,  and  multiple  exclusion
	      (default: /var/run/rngd.pid)

       -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).

       -d 1|0, --no-drng=1|0
	      Do not use drng as a source of random number input (default:0)

       -n 1|0, --no-tpm=1|0
	      Do not use tpm as a source of random number input (default:0)

       -q, --quiet
	      Suppress error messages

       -v, --verbose
	      Report available entropy sources

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

       -V, --version
	      Print program version

AUTHORS
       Philipp Rumpf
       Jeff Garzik - jgarzik@pobox.com
       Matt Sottek
       Brad Hill

rng-tools 4			  March 2001			       RNGD(8)

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