rndctl(8) - NetBSD Manual Pages

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RNDCTL(8)               NetBSD System Manager's Manual               RNDCTL(8)


NAME

     rndctl -- in-kernel random number generator management tool


SYNOPSIS

     rndctl [-CcEe] [-d devname | -t devtype]
     rndctl [-lsv] [-d devname | -t devtype]
     rndctl -L save-file
     rndctl -S save-file


DESCRIPTION

     The rndctl program displays statistics on the current state of the rnd(4)
     pseudo-driver, and allows the administrator to control which sources are
     allowed to contribute to the randomness pool maintained by rnd(4), as
     well as whether a given source counts as strongly random.

     The following options are available:

     -C      Disable collection of timing information for the given device
             name or device type.

     -c      Enable collection of timing information for the given device name
             or device type.

     -d      Only the device named devname is altered or displayed.  This is
             mutually exclusive with -t.

     -E      Disable entropy estimation from the collected timing information
             for the given device name or device type.  If collection is still
             enabled, timing information is still collected and mixed into the
             internal entropy pool, but no entropy is assumed to be present.

     -e      Enable entropy estimation using the collected timing information
             for the given device name or device type.

     -L      Load saved entropy from file save-file and overwrite it with a
             seed derived by hashing it together with output from /dev/urandom
             so that the new seed has at least as much entropy as either the
             old seed had or the system already has.  If interrupted, either
             the old seed or the new seed will be in place.

     -l      List all sources, or, if the -t or -d flags are specified, only
             those specified by the devtype or devname specified.

     -S      Save entropy pool to file save-file.  The file format is specific
             to rndctl and includes an estimate of the amount of saved entropy
             and a checksum.

     -s      Display statistics on the current state of the random collection
             pool.

     -t      All devices of type devtype are altered or displayed.  This is
             mutually exclusive with -d.

             The available types are:

             disk   Physical hard drives.

             net    Network interfaces.

             tape   Tape devices.

             tty    Terminal, mouse, or other user input devices.

             rng    Random number generators.

     -v      Verbose output: show entropy estimation statistics for each
             source.


FILES

     /dev/random    Returns ``good'' values only.
     /dev/urandom   Always returns data, degenerates to a pseudo-random gener-
                    ator.


SEE ALSO

     rnd(4), rnd(9)


HISTORY

     The rndctl program was first made available in NetBSD 1.3.


AUTHORS

     The rndctl program was written by Michael Graff <explorer@flame.org>.


BUGS

     Turning on entropy estimation from unsafe or predictable sources will
     weaken system security, while turning on entropy collection from such
     sources may weaken system security.

     Care should be taken when using this command.

NetBSD 9.2                      August 10, 2014                     NetBSD 9.2