RNGD(8)

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

SYNOPSIS
rngd [-b, --background] [-f, --foreground] [-d, --debug] [-l, --list] [-x, --exclude] [-i, --ignorefail] [-o, --random-device=file] [-p, --pid-file=file] [-r, --rng-device=file] [-s, --random-step=nnn] [-W, --fill-watermark=nnn] [-q, --quiet] [-?, --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/hwrng. 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

-d, --debug
    Enable debug messages

-l, --list
    List the indexes and names of available entropy sources. Exit code when listing sources is 0 if at least 1 entropy source was found and initialized, 1 otherwise.

-x, --exclude
    Disable entropy sources based on index reported from --list option

-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/hwrng)

-s nnn, --random-step=nnn
    Number of bytes written to random-device at a time (default: 64)

-e nnn, --entropy-count=nnn
    Number of bits to consider random when adding entropy. 1<=e<=8 (default: 8)

-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. By default, this value is set to 75% of the entropy pool size or 2048 bits if the entropy pool size couldn't be determined. 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).

-q, --quiet
    Suppress error messages

-?, --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
Neil Horman - nhorman@tuxdriver.com