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

NAME
     rndctl — in-kernel random number generator management tool

SYNOPSIS
     rndctl -CcEe [-d devname | -t devtype]
     rndctl -ls [-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, which will be overwritten
	     and deleted before the entropy is loaded into the kernel.

     -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.

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.

BSD			       November 23, 2011			   BSD

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