RNDCTL(8) BSD System Manager's Manual RNDCTL(8)
rndctl -- in-kernel random number generator management tool
rndctl -CcEe [-d devname] [-t devtype]
rndctl -ls [-d devname] [-t devtype]
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
of device type.
-d Only the device named devname is altered or displayed. See also
-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 List all sources, or, if the -t or -d flags are specified, only
those specified by the devtype or devname specified.
-s Display statistics on the current state of the random collection
-t All devices of type devtype are altered or displayed. See also
/dev/random Returns ``good'' values only.
/dev/urandom Always returns data, degenerates to a pseudo-random gener-
The rndctl program was first made available in NetBSD 1.3.
The rndctl program was written by Michael Graff <explorerATflame.org>.
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 October 1, 2002 BSD