1.\" 2.\" Copyright (c) 1995 3.\" Mark Murray. All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY MARK MURRAY AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.\" $FreeBSD: src/usr.sbin/rndcontrol/rndcontrol.8,v 1.13.2.2 2001/12/21 09:05:32 ru Exp $ 27.\" $DragonFly: src/usr.sbin/rndcontrol/rndcontrol.8,v 1.7 2007/06/13 14:27:41 swildner Exp $ 28.\" 29.Dd October 20, 1995 30.Dt RNDCONTROL 8 31.Os 32.Sh NAME 33.Nm rndcontrol 34.Nd a utility for manipulating the 35.Pa /dev/random 36device 37.Sh SYNOPSIS 38.Nm 39.Op Fl q 40.Op Fl s Ar irq_no 41.Op Fl c Ar irq_no 42.Sh DESCRIPTION 43The 44.Nm 45command is used to set which interrupts are used to help add entropy 46to the CSPRNG maintained by the kernel. 47The 48.Pa /dev/random 49and 50.Pa /dev/urandom 51devices are the user interface to this source of randomness. 52Any changes take effect immediately. 53.Pp 54The following command line options are supported: 55.Bl -tag -width indent 56.It Fl q 57Turn off all output except errors. 58.It Fl s Ar n 59Allow IRQ 60.Ar n 61to be used as a source of randomness. 62This option may be repeated for 63more than one IRQ. 64.It Fl c Ar n 65Stop IRQ 66.Ar n 67from being used as a source of randomness. 68This option may be repeated for 69more than one IRQ. 70.El 71.Pp 72By default, all IRQs will help develop entropy. The kernel uses a 73rate-limited helper thread to add the actual entropy and even fast 74interrupts should not detrimentally affect a running system. 75.Sh FILES 76.Bl -tag -width ".Pa /dev/urandom" -compact 77.It Pa /dev/random 78secure random device 79.It Pa /dev/urandom 80random device 81.El 82.Sh SEE ALSO 83.Xr srandomdev 3 , 84.Xr random 4 85.Sh HISTORY 86The 87.Nm 88utility first appeared in 89.Fx 2.1.5 . 90.Sh AUTHORS 91.An -nosplit 92.An Theodore Ts'o 93wrote the core code. 94.An Mark Murray 95ported this code to 96.Fx 97and wrote the support routines and constructed the man pages. 98.Sh BUGS 99Sure to be some. 100