+++ /dev/null
-<?xml version="1.0"?>
-<!--*-nxml-*-->
-<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
-<!--
- This file is part of systemd.
-
- Copyright 2012 Lennart Poettering
-
- systemd is free software; you can redistribute it and/or modify it
- under the terms of the GNU Lesser General Public License as published by
- the Free Software Foundation; either version 2.1 of the License, or
- (at your option) any later version.
-
- systemd is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
-
- You should have received a copy of the GNU Lesser General Public License
- along with systemd; If not, see <http://www.gnu.org/licenses/>.
-
- This is based on crypttab(5) from Fedora's initscripts package, which in
- turn is based on Debian's version.
-
- The Red Hat version has been written by Miloslav Trmac <mitr@redhat.com>.
-
--->
-<refentry id="crypttab" conditional='HAVE_LIBCRYPTSETUP'>
-
- <refentryinfo>
- <title>crypttab</title>
- <productname>systemd</productname>
-
- <authorgroup>
- <author>
- <contrib>Documentation</contrib>
- <firstname>Miloslav</firstname>
- <surname>Trmac</surname>
- <email>mitr@redhat.com</email>
- </author>
- <author>
- <contrib>Documentation</contrib>
- <firstname>Lennart</firstname>
- <surname>Poettering</surname>
- <email>lennart@poettering.net</email>
- </author>
- </authorgroup>
- </refentryinfo>
-
- <refmeta>
- <refentrytitle>crypttab</refentrytitle>
- <manvolnum>5</manvolnum>
- </refmeta>
-
- <refnamediv>
- <refname>crypttab</refname>
- <refpurpose>Configuration for encrypted block devices</refpurpose>
- </refnamediv>
-
- <refsynopsisdiv>
- <para><filename>/etc/crypttab</filename></para>
- </refsynopsisdiv>
-
- <refsect1>
- <title>Description</title>
-
- <para>The <filename>/etc/crypttab</filename> file describes
- encrypted block devices that are set up during system boot.</para>
-
- <para>Empty lines and lines starting with the <literal>#</literal>
- character are ignored. Each of the remaining lines describes one
- encrypted block device, fields on the line are delimited by white
- space. The first two fields are mandatory, the remaining two are
- optional.</para>
-
- <para>Setting up encrypted block devices using this file supports
- three encryption modes: LUKS, TrueCrypt and plain. See
- <citerefentry project='die-net'><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- for more information about each mode. When no mode is specified in
- the options field and the block device contains a LUKS signature,
- it is opened as a LUKS device; otherwise, it is assumed to be in
- raw dm-crypt (plain mode) format.</para>
-
- <para>The first field contains the name of the resulting encrypted
- block device; the device is set up within
- <filename>/dev/mapper/</filename>.</para>
-
- <para>The second field contains a path to the underlying block
- device or file, or a specification of a block device via
- <literal>UUID=</literal> followed by the UUID.</para>
-
- <para>The third field specifies the encryption password. If the
- field is not present or the password is set to
- <literal>none</literal> or <literal>-</literal>, the password has
- to be manually entered during system boot. Otherwise, the field is
- interpreted as a absolute path to a file containing the encryption
- password. For swap encryption, <filename>/dev/urandom</filename>
- or the hardware device <filename>/dev/hw_random</filename> can be
- used as the password file; using <filename>/dev/random</filename>
- may prevent boot completion if the system does not have enough
- entropy to generate a truly random encryption key.</para>
-
- <para>The fourth field, if present, is a comma-delimited list of
- options. The following options are recognized:</para>
-
- <variablelist class='fstab-options'>
-
- <varlistentry>
- <term><option>discard</option></term>
-
- <listitem><para>Allow discard requests to be passed through
- the encrypted block device. This improves performance on SSD
- storage but has security implications.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>cipher=</option></term>
-
- <listitem><para>Specifies the cipher to use. See
- <citerefentry project='die-net'><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- for possible values and the default value of this option. A
- cipher with unpredictable IV values, such as
- <literal>aes-cbc-essiv:sha256</literal>, is
- recommended.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>hash=</option></term>
-
- <listitem><para>Specifies the hash to use for password
- hashing. See
- <citerefentry project='die-net'><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- for possible values and the default value of this
- option.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>header=</option></term>
-
- <listitem><para>Use a detached (separated) metadata device or
- file where the LUKS header is stored. This option is only
- relevant for LUKS devices. See
- <citerefentry project='die-net'><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- for possible values and the default value of this
- option.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>keyfile-offset=</option></term>
-
- <listitem><para>Specifies the number of bytes to skip at the
- start of the key file. See
- <citerefentry project='die-net'><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- for possible values and the default value of this
- option.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>keyfile-size=</option></term>
-
- <listitem><para>Specifies the maximum number of bytes to read
- from the key file. See
- <citerefentry project='die-net'><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- for possible values and the default value of this option. This
- option is ignored in plain encryption mode, as the key file
- size is then given by the key size.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>key-slot=</option></term>
-
- <listitem><para>Specifies the key slot to compare the
- passphrase or key against. If the key slot does not match the
- given passphrase or key, but another would, the setup of the
- device will fail regardless. This option implies
- <option>luks</option>. See
- <citerefentry project='die-net'><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- for possible values. The default is to try all key slots in
- sequential order.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>luks</option></term>
-
- <listitem><para>Force LUKS mode. When this mode is used, the
- following options are ignored since they are provided by the
- LUKS header on the device: <option>cipher=</option>,
- <option>hash=</option>,
- <option>size=</option>.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>noauto</option></term>
-
- <listitem><para>This device will not be automatically unlocked
- on boot.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>nofail</option></term>
-
- <listitem><para>The system will not wait for the device to
- show up and be unlocked at boot, and not fail the boot if it
- does not show up.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>plain</option></term>
-
- <listitem><para>Force plain encryption mode.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>read-only</option></term><term><option>readonly</option></term>
-
- <listitem><para>Set up the encrypted block device in read-only
- mode.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>size=</option></term>
-
- <listitem><para>Specifies the key size in bits. See
- <citerefentry project='die-net'><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- for possible values and the default value of this
- option.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>swap</option></term>
-
- <listitem><para>The encrypted block device will be used as a
- swap device, and will be formatted accordingly after setting
- up the encrypted block device, with
- <citerefentry project='man-pages'><refentrytitle>mkswap</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
- This option implies <option>plain</option>.</para>
-
- <para>WARNING: Using the <option>swap</option> option will
- destroy the contents of the named partition during every boot,
- so make sure the underlying block device is specified
- correctly.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>tcrypt</option></term>
-
- <listitem><para>Use TrueCrypt encryption mode. When this mode
- is used, the following options are ignored since they are
- provided by the TrueCrypt header on the device or do not
- apply:
- <option>cipher=</option>,
- <option>hash=</option>,
- <option>keyfile-offset=</option>,
- <option>keyfile-size=</option>,
- <option>size=</option>.</para>
-
- <para>When this mode is used, the passphrase is read from the
- key file given in the third field. Only the first line of this
- file is read, excluding the new line character.</para>
-
- <para>Note that the TrueCrypt format uses both passphrase and
- key files to derive a password for the volume. Therefore, the
- passphrase and all key files need to be provided. Use
- <option>tcrypt-keyfile=</option> to provide the absolute path
- to all key files. When using an empty passphrase in
- combination with one or more key files, use
- <literal>/dev/null</literal> as the password file in the third
- field.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>tcrypt-hidden</option></term>
-
- <listitem><para>Use the hidden TrueCrypt volume. This option
- implies <option>tcrypt</option>.</para>
-
- <para>This will map the hidden volume that is inside of the
- volume provided in the second field. Please note that there is
- no protection for the hidden volume if the outer volume is
- mounted instead. See
- <citerefentry project='die-net'><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- for more information on this limitation.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>tcrypt-keyfile=</option></term>
-
- <listitem><para>Specifies the absolute path to a key file to
- use for a TrueCrypt volume. This implies
- <option>tcrypt</option> and can be used more than once to
- provide several key files.</para>
-
- <para>See the entry for <option>tcrypt</option> on the
- behavior of the passphrase and key files when using TrueCrypt
- encryption mode.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>tcrypt-system</option></term>
-
- <listitem><para>Use TrueCrypt in system encryption mode. This
- option implies <option>tcrypt</option>.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>timeout=</option></term>
-
- <listitem><para>Specifies the timeout for querying for a
- password. If no unit is specified, seconds is used. Supported
- units are s, ms, us, min, h, d. A timeout of 0 waits
- indefinitely (which is the default).</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>x-systemd.device-timeout=</option></term>
-
- <listitem><para>Specifies how long systemd should wait for a
- device to show up before giving up on the entry. The argument
- is a time in seconds or explicitly specified units of
- <literal>s</literal>,
- <literal>min</literal>,
- <literal>h</literal>,
- <literal>ms</literal>.
- </para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>tmp</option></term>
-
- <listitem><para>The encrypted block device will be prepared
- for using it as <filename>/tmp</filename>; it will be
- formatted using
- <citerefentry project='man-pages'><refentrytitle>mke2fs</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
- This option implies <option>plain</option>.</para>
-
- <para>WARNING: Using the <option>tmp</option> option will
- destroy the contents of the named partition during every boot,
- so make sure the underlying block device is specified
- correctly.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>tries=</option></term>
-
- <listitem><para>Specifies the maximum number of times the user
- is queried for a password. The default is 3. If set to 0, the
- user is queried for a password indefinitely.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><option>verify</option></term>
-
- <listitem><para> If the encryption password is read from
- console, it has to be entered twice to prevent
- typos.</para></listitem>
- </varlistentry>
-
- </variablelist>
-
- <para>At early boot and when the system manager configuration is
- reloaded, this file is translated into native systemd units by
- <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
- </refsect1>
-
- <refsect1>
- <title>Example</title>
- <example>
- <title>/etc/crypttab example</title>
- <para>Set up four encrypted block devices. One using LUKS for
- normal storage, another one for usage as a swap device and two
- TrueCrypt volumes.</para>
-
- <programlisting>luks UUID=2505567a-9e27-4efe-a4d5-15ad146c258b
-swap /dev/sda7 /dev/urandom swap
-truecrypt /dev/sda2 /etc/container_password tcrypt
-hidden /mnt/tc_hidden /dev/null tcrypt-hidden,tcrypt-keyfile=/etc/keyfile</programlisting>
- </example>
- </refsect1>
-
- <refsect1>
- <title>See Also</title>
- <para>
- <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemd-cryptsetup@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
- <citerefentry project='die-net'><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
- <citerefentry project='man-pages'><refentrytitle>mkswap</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
- <citerefentry project='man-pages'><refentrytitle>mke2fs</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- </para>
- </refsect1>
-
-</refentry>
~ianmdlvl / elogind.git / blobdiff