1.\" $NetBSD: rndctl.8,v 1.18 2011/10/01 02:55:00 pgoyette Exp $ 2.\" 3.\" Copyright (c) 1997 Michael Graff 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. The name of the author may not be used to endorse or promote products 15.\" derived from this software without specific prior written permission. 16.\" 17.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 22.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 23.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 24.\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 25.\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27.\" SUCH DAMAGE. 28.\" 29.Dd January 4, 2009 30.Dt RNDCTL 8 31.Os 32.Sh NAME 33.Nm rndctl 34.Nd in-kernel random number generator management tool 35.Sh SYNOPSIS 36.Nm 37.Fl CcEe 38.Op Fl d Ar devname | Fl t Ar devtype 39.Nm 40.Fl ls 41.Op Fl d Ar devname | Fl t Ar devtype 42.Sh DESCRIPTION 43The 44.Nm 45program displays statistics on the current state of the 46.Xr rnd 4 47pseudo-driver, and allows the administrator to control which sources 48are allowed to contribute to the randomness pool maintained by 49.Xr rnd 4 , 50as well as whether a given source counts as strongly random. 51.Pp 52The following options are available: 53.Bl -tag -width 123456 54.It Fl C 55Disable collection of timing information for the given 56device name or device type. 57.It Fl c 58Enable collection of timing information for the given 59device name or device type. 60.It Fl d 61Only the device named 62.Ar devname 63is altered or displayed. 64This is mutually exclusive with 65.Fl t . 66.It Fl E 67Disable entropy estimation from the collected timing information for 68the given device name or device type. 69If collection is still enabled, timing information is still 70collected and mixed into the internal entropy pool, 71but no entropy is assumed to be present. 72.It Fl e 73Enable entropy estimation using the collected timing information 74for the given device name or device type. 75.It Fl l 76List all sources, or, if the 77.Fl t 78or 79.Fl d 80flags are specified, only those specified by the 81.Ar devtype 82or 83.Ar devname 84specified. 85.It Fl s 86Display statistics on the current state of the random collection pool. 87.It Fl t 88All devices of type 89.Ar devtype 90are altered or displayed. 91This is mutually exclusive with 92.Fl d . 93.Pp 94The available types are: 95.Bl -tag -width "diskx" 96.It Ic disk 97Physical hard drives. 98.It Ic net 99Network interfaces. 100.It Ic tape 101Tape devices. 102.It Ic tty 103Terminal, mouse, or other user input devices. 104.It Ic rng 105Random number generators. 106.El 107.El 108.Sh FILES 109.Bl -tag -width /dev/urandomx -compact 110.It Pa /dev/random 111Returns 112.Dq good 113values only. 114.It Pa /dev/urandom 115Always returns data, degenerates to a pseudo-random generator. 116.El 117.Sh SEE ALSO 118.Xr rnd 4 , 119.Xr rnd 9 120.Sh HISTORY 121The 122.Nm 123program was first made available in 124.Nx 1.3 . 125.Sh AUTHORS 126The 127.Nm 128program was written by 129.An Michael Graff 130.Aq explorer@flame.org . 131.Sh BUGS 132Turning on entropy estimation from unsafe or predictable sources will 133weaken system security, while turning on entropy collection from such 134sources may weaken system security. 135.Pp 136Care should be taken when using this command. 137