1.\" $NetBSD: rndctl.8,v 1.22 2014/08/10 17:13:02 wiz 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 August 10, 2014 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.Op Fl CcEe 38.Op Fl d Ar devname | Fl t Ar devtype 39.Nm 40.Op Fl lsv 41.Op Fl d Ar devname | Fl t Ar devtype 42.Nm 43.Fl L Ar save-file 44.Nm 45.Fl S Ar save-file 46.Sh DESCRIPTION 47The 48.Nm 49program displays statistics on the current state of the 50.Xr rnd 4 51pseudo-driver, and allows the administrator to control which sources 52are allowed to contribute to the randomness pool maintained by 53.Xr rnd 4 , 54as well as whether a given source counts as strongly random. 55.Pp 56The following options are available: 57.Bl -tag -width 123456 58.It Fl C 59Disable collection of timing information for the given 60device name or device type. 61.It Fl c 62Enable collection of timing information for the given 63device name or device type. 64.It Fl d 65Only the device named 66.Ar devname 67is altered or displayed. 68This is mutually exclusive with 69.Fl t . 70.It Fl E 71Disable entropy estimation from the collected timing information for 72the given device name or device type. 73If collection is still enabled, timing information is still 74collected and mixed into the internal entropy pool, 75but no entropy is assumed to be present. 76.It Fl e 77Enable entropy estimation using the collected timing information 78for the given device name or device type. 79.It Fl L 80Load saved entropy from file 81.Ar save-file , 82which will be overwritten and deleted before the entropy is loaded into 83the kernel. 84.It Fl l 85List all sources, or, if the 86.Fl t 87or 88.Fl d 89flags are specified, only those specified by the 90.Ar devtype 91or 92.Ar devname 93specified. 94.It Fl S 95Save entropy pool to file 96.Ar save-file . 97The file format is specific to 98.Nm 99and includes an estimate of the amount of saved entropy and a checksum. 100.It Fl s 101Display statistics on the current state of the random collection pool. 102.It Fl t 103All devices of type 104.Ar devtype 105are altered or displayed. 106This is mutually exclusive with 107.Fl d . 108.Pp 109The available types are: 110.Bl -tag -width "diskx" 111.It Ic disk 112Physical hard drives. 113.It Ic net 114Network interfaces. 115.It Ic tape 116Tape devices. 117.It Ic tty 118Terminal, mouse, or other user input devices. 119.It Ic rng 120Random number generators. 121.El 122.It Fl v 123Verbose output: show entropy estimation statistics for each source. 124.El 125.Sh FILES 126.Bl -tag -width /dev/urandomx -compact 127.It Pa /dev/random 128Returns 129.Dq good 130values only. 131.It Pa /dev/urandom 132Always returns data, degenerates to a pseudo-random generator. 133.El 134.Sh SEE ALSO 135.Xr rnd 4 , 136.Xr rnd 9 137.Sh HISTORY 138The 139.Nm 140program was first made available in 141.Nx 1.3 . 142.Sh AUTHORS 143The 144.Nm 145program was written by 146.An Michael Graff 147.Aq explorer@flame.org . 148.Sh BUGS 149Turning on entropy estimation from unsafe or predictable sources will 150weaken system security, while turning on entropy collection from such 151sources may weaken system security. 152.Pp 153Care should be taken when using this command. 154