RNGD
Section: Maintenance Commands (8)
Updated: March 2001
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NAME
rngd - Check and feed random data from hardware device to kernel random device
SYNOPSIS
rngd
[-b, --background]
[-f, --foreground]
[-o, --random-device=file]
[-r, --rng-device=file]
[-s, --random-step=nnn]
[-W, --fill-watermark=nnn]
[-t, --timeout=nnn]
[-?, --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 -f or --foreground 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.
FIXME: document random-step and timeout
OPTIONS
- -b, --background
-
Become a daemon (default)
- -f, --foreground
-
Do not fork and become a daemon
- -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).
- -t nnn, --timeout=nnn
-
Interval written to random-device when the entropy pool is full, in seconds, or 0 to disable (default: 60)
- -?, --help
-
Give a short summary of all program options.
- -V, --version
-
Print program version
AUTHORS
Philipp Rumpf
Jeff Garzik - jgarzik@pobox.com
Matt Sottek