1RNGD(8)                     System Manager's Manual                    RNGD(8)
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NAME

6       rngd - Check and feed random data from hardware device to kernel random
7       device
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SYNOPSIS

11       rngd [-b, --background] [-f, --foreground]  [-o,  --random-device=file]
12       [-r,  --rng-device=file]  [-s,  --random-step=nnn]  [-W,  --fill-water‐
13       mark=nnn] [-t, --timeout=nnn] [-?, --help] [-V, --version]
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DESCRIPTION

17       This daemon feeds data from a random number generator to  the  kernel's
18       random  number  entropy  pool,  after first checking the data to ensure
19       that it is properly random.
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21       The -f or --foreground options can be used to tell rngd to avoid  fork‐
22       ing  on  startup.   This  is  typically  used for debugging.  The -f or
23       --foreground options, which fork and put rngd into the background auto‐
24       matically, are the default.
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26       The  -r  or  --rng-device  options  can  be used to select an alternate
27       source of input, besides the default /dev/hwrandom.  The -o  or  --ran‐
28       dom-device  options  can  be used to select an alternate entropy output
29       device, besides the default /dev/random.  Note that  this  device  must
30       support the Linux kernel /dev/random ioctl API.
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32       FIXME: document random-step and timeout
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OPTIONS

36       -b, --background
37              Become a daemon (default)
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39       -f, --foreground
40              Do not fork and become a daemon
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42       -o file, --random-device=file
43              Kernel  device used for random number output (default: /dev/ran‐
44              dom)
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46       -r file, --rng-device=file
47              Kernel device used for random number input (default: /dev/hwran‐
48              dom)
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50       -s nnn, --random-step=nnn
51              Number of bytes written to random-device at a time (default: 64)
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53       -W n, --fill-watermark=nnn
54              Once  we  start doing it, feed entropy to random-device until at
55              least fill-watermark  bits  of  entropy  are  available  in  its
56              entropy  pool (default: 2048).  Setting this too high will cause
57              rngd to dominate the contents of the entropy pool.   Low  values
58              will hurt system performance during entropy starves.  Do not set
59              fill-watermark above the size of the entropy pool (usually  4096
60              bits).
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62       -t nnn, --timeout=nnn
63              Interval written to random-device when the entropy pool is full,
64              in seconds, or 0 to disable (default: 60)
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66       -?, --help
67              Give a short summary of all program options.
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69       -V, --version
70              Print program version
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AUTHORS

74       Philipp Rumpf
75       Jeff Garzik - jgarzik@pobox.com
76       Matt Sottek
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81rng-tools 2                       March 2001                           RNGD(8)
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