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.\" Copyright (C) 2001 Jeff Garzik -- jgarzik@pobox.com
.\"
.TH RNGD 8 "March 2001" "@PACKAGE@ @VERSION@"
.SH NAME
rngd \- Check and feed random data from hardware device to kernel random device
.SH SYNOPSIS
.B rngd
[\fB\-b\fR, \fB\-\-background\fR]
[\fB\-f\fR, \fB\-\-foreground\fR]
[\fB\-o\fR, \fB\-\-random-device=\fIfile\fR]
[\fB\-r\fR, \fB\-\-rng-device=\fIfile\fR]
[\fB\-s\fR, \fB\-\-random-step=\fInnn\fR]
[\fB\-W\fR, \fB\-\-fill-watermark=\fInnn\fR]
[\fB\-t\fR, \fB\-\-timeout=\fInnn\fR]
[\fB\-?\fR, \fB\-\-help\fR]
[\fB\-V\fR, \fB\-\-version\fR]
.RI
.SH 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.
.PP
The \fB\-f\fR or \fB\-\-foreground\fR options can be used to tell
\fBrngd\fR to avoid forking on startup. This is typically used for
debugging. The \fB\-f\fR or \fB\-\-foreground\fR options, which fork and put
\fBrngd\fR into the background automatically, are the default.
.PP
The \fB\-r\fR or \fB\-\-rng-device\fR options can be used to select an
alternate source of input, besides the default /dev/hwrandom.
The \fB\-o\fR or \fB\-\-random-device\fR 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.
.PP
FIXME: document random-step and timeout
.SH OPTIONS
.TP
\fB\-b\fR, \fB\-\-background\fR
Become a daemon (default)
.TP
\fB\-f\fR, \fB\-\-foreground\fR
Do not fork and become a daemon
.TP
\fB\-o\fI file\fR, \fB\-\-random-device=\fIfile\fR
Kernel device used for random number output
(default: /dev/random)
.TP
\fB\-r\fI file\fR, \fB\-\-rng-device=\fIfile\fR
Kernel device used for random number input
(default: /dev/hwrandom)
.TP
\fB\-s\fI nnn\fR, \fB\-\-random-step=\fInnn\fR
Number of bytes written to random-device at a time (default: 64)
.TP
\fB\-W\fI n\fR, \fB\-\-fill\-watermark=\fInnn\fR
Once we start doing it, feed entropy to \fIrandom-device\fR until at least
\fIfill-watermark\fR bits of entropy are available in its entropy pool (default: 2048).
Setting this too high will cause \fIrngd\fR to dominate the contents of the
entropy pool. Low values will hurt system performance during entropy
starves. Do not set \fIfill-watermark\fR above the size of the
entropy pool (usually 4096 bits).
.TP
\fB\-t\fI nnn\fR, \fB\-\-timeout=\fInnn\fR
Interval written to random-device when the entropy pool is full, in seconds, or 0 to disable (default: 60)
.TP
\fB\-?\fR, \fB\-\-help\fR
Give a short summary of all program options.
.TP
\fB\-V\fR, \fB\-\-version\fR
Print program version
.SH AUTHORS
Philipp Rumpf
.br
Jeff Garzik \- jgarzik@pobox.com
.br
Matt Sottek
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