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