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       [-p,  --pid-file=file]  [-r, --rng-device=file] [-s, --random-step=nnn]
13       [-W, --fill-watermark=nnn] [-d, --no-drng=1|0] [-n, --no-tpm=1|0]  [-t,
14       --timeout=nnn]  [-q,  --quiet] [-v, --verbose] [-?, --help] [-V, --ver‐
15       sion]
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DESCRIPTION

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

35       -b, --background
36              Become a daemon (default)
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38       -f, --foreground
39              Do not fork and become a daemon
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41       -i, --ignorefail
42              Ignore repeated fips failures.
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44       -p file, --pid-file=file
45              File  used  for  recording  daemon  PID,  and multiple exclusion
46              (default: /var/run/rngd.pid)
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48       -o file, --random-device=file
49              Kernel device used for random number output (default:  /dev/ran‐
50              dom)
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52       -r file, --rng-device=file
53              Kernel device used for random number input (default: /dev/hwran‐
54              dom)
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56       -s nnn, --random-step=nnn
57              Number of bytes written to random-device at a time (default: 64)
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59       -W n, --fill-watermark=nnn
60              Once we start doing it, feed entropy to random-device  until  at
61              least  fill-watermark  bits  of  entropy  are  available  in its
62              entropy pool (default: 2048).  Setting this too high will  cause
63              rngd  to  dominate the contents of the entropy pool.  Low values
64              will hurt system performance during entropy starves.  Do not set
65              fill-watermark  above the size of the entropy pool (usually 4096
66              bits).
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68       -d 1|0, --no-drng=1|0
69              Do not use drng as a source of random number input (default:0)
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71       -n 1|0, --no-tpm=1|0
72              Do not use tpm as a source of random number input (default:0)
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74       -t nnn, --timeout=nnn
75              Interval written to random-device when the entropy pool is full.
76              Note  that  this  option  exists  for  backward compatibility in
77              RHEL6, but is ignored.  Rngd now correctly waits  until  writing
78              to a random-device will not block.
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80       -q, --quiet
81              Suppress error messages
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83       -v, --verbose
84              Report available entropy sources
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86       -?, --help
87              Give a short summary of all program options.
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89       -V, --version
90              Print program version
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AUTHORS

94       Philipp Rumpf
95       Jeff Garzik - jgarzik@pobox.com
96       Matt Sottek
97       Brad Hill
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101rng-tools 5                       March 2001                           RNGD(8)