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![Fernando Apesteguía](/assets/img/avatar_default.png)
Succinct manual page for save-entropy(8). PR: 223998 Reported by: AJ Jordan <alex+freebsd@strugee.net> Reviewed by: carlavilla@, delphij@, lwhsu@, pauamma_gundo.com Approved by: delphi, lwhsu (src) Differential Revision: https://reviews.freebsd.org/D41768
98 lines
2.9 KiB
Groff
98 lines
2.9 KiB
Groff
.\"
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.\" SPDX-License-Identifier: BSD-2-Clause
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.\"
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.\" Copyright (c) 2023 Fernando Apesteguia <fernando.apesteguia@gmail.com>
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.Dd September 18, 2023
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.Dt SAVE-ENTROPY 8
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.Os
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.Sh NAME
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.Nm save-entropy
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.Nd Save bits of entropy to feed /dev/random at startup
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.Sh SYNOPSIS
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.Nm save-entropy
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.Sh DESCRIPTION
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The
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.Nm
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command is used to save entropy data from
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.Pa /dev/random
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to files in a specified output location.
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The files saved are used at startup to provide additional entropy for
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.Pa /dev/random .
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The output file will be different in every invocation until the maximum number
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of different files is reached.
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(See
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.Em entropy_save_num
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for details).
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By default this script is invoked via
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.Xr cron 8
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every eleven minutes approximately.
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.Pp
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This command does nothing if executed inside a
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.Xr jail 8 .
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.Pp
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Three variables in
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.Pa /etc/rc.conf
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regulate the behavior of the script:
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.Bl -tag -width Ds
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.It Va entropy_dir
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Specify the directory for saved entropy files.
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Defaults to
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.Pa /var/db/entropy .
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If set to "NO" it disables caching entropy via
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.Xr cron 8 .
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This setting is shared with
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.Pa /etc/rc.d/random .
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.It Va entropy_save_sz
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Size of the entropy cache files.
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Defaults to 4096.
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.It Va entropy_save_num
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Number of entropy cache files to save.
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Defaults to 8.
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.El
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.Sh FILES
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.Bl -tag -width Ds
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.It Pa /etc/rc.conf
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.El
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.Sh EXIT STATUS
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.Ex -std
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Errors will be recorded in the system log.
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.Sh SEE ALSO
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.Xr syslog 3 ,
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.Xr random 4 ,
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.Xr rc.conf 5 ,
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.Xr cron 8
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.Sh HISTORY
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The
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.Nm
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command first appeared in
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.Fx 5.0 .
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.Sh AUTHORS
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The
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.Nm
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command was originally written by
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.An Doug Barton <dougb@FreeBSD.org> .
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This manual page was written by
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.An Fernando Apesteguia <fernape@FreeBSD.org> .
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