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 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 support the Linux kernel /dev/random ioctl API.

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/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