centos man page for rngd

RNGD(8) 						      System Manager's Manual							   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] [-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, --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 forking on startup.  This is typically used  for  debugging.   The  -b	or
       --background 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/random.  Note that this device must  sup-
       port 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)

       -i, --ignorefail
	      Ignore repeated fips failures

       -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).

       -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)