The Red Hat version has been written by Miloslav Trmac <mitr@redhat.com>.
-->
-<refentry id="crypttab">
-
- <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 #
- 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>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 a specification of a block
- device via <literal>UUID=</literal> followed by the
- UUID. If the block device contains a LUKS signature,
- it is opened as a LUKS encrypted partition; otherwise
- it is assumed to be a raw dm-crypt partition.</para>
-
- <para>The third field specifies the encryption
- password. If the field is not present or the password
- is set to none, the password has to be manually
- entered during system boot. Otherwise the field is
- interpreted as a 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>
- <varlistentry>
- <term><varname>cipher=</varname></term>
-
- <listitem><para>Specifies the cipher
- to use; see
- <citerefentry><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><varname>size=</varname></term>
-
- <listitem><para>Specifies the key size
- in bits; see
- <citerefentry><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- for possible values and the default
- value of this
- option. </para></listitem>
- </varlistentry>
-
-
- <varlistentry>
- <term><varname>keyfile-size=</varname></term>
-
- <listitem><para>Specifies the maximum number
- of bytes to read from the keyfile; see
- <citerefentry><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 keyfile-size is then given by the key size.</para></listitem>
- </varlistentry>
-
-
- <varlistentry>
- <term><varname>keyfile-offset=</varname></term>
-
- <listitem><para>Specifies the number
- of bytes to skip at the start of
- the keyfile; see
- <citerefentry><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- for possible values and the default
- value of this option.</para></listitem>
- </varlistentry>
-
-
- <varlistentry>
- <term><varname>hash=</varname></term>
-
- <listitem><para>Specifies the hash to
- use for password hashing; see
- <citerefentry><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry> for possible values and
- the default value of this
- option. </para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>tries=</varname></term>
-
- <listitem><para>Specifies the maximum
- number of times the user is queried
- for a password.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>verify</varname></term>
-
- <listitem><para> If the the encryption
- password is read from console, it has
- to be entered twice (to prevent
- typos). </para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>read-only</varname></term>
-
- <listitem><para>Set up the encrypted
- block device in read-only
- mode.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>allow-discards</varname></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><varname>luks</varname></term>
-
- <listitem><para>Force LUKS mode.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>plain</varname></term>
-
- <listitem><para>Force plain encryption
- mode.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>timeout=</varname></term>
-
- <listitem><para>Specify the timeout
- for querying for a password. If not
- unit is specified in
- seconds. Supported units are s, ms,
- us, min, h, d.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>noauto</varname></term>
-
- <listitem><para> This device will not
- be automatically unlocked on
- boot. </para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>nofail</varname></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 doesn't show
- up.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>swap</varname></term>
-
- <listitem><para> The encrypted block
- device will be used as a swap
- partition, and will be formatted as a
- swap partition after setting up the
- encrypted block device, with
- <citerefentry><refentrytitle>mkswap</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
-
- <para>WARNING: Using the
- <varname>swap</varname> 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><varname>tmp</varname></term>
-
- <listitem><para>The encrypted block
- device will be prepared for using it
- as <filename>/tmp</filename>
- partition: it will be formatted using
- <citerefentry><refentrytitle>mke2fs</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
-
- <para>WARNING: Using the
- <varname>tmp</varname> 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>
- </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 two encrypted block devices with
- LUKS: one normal one for storage, and another
- one for usage as swap device.</para>
-
- <programlisting>luks-2505567a-9e27-4efe-a4d5-15ad146c258b UUID=2505567a-9e27-4efe-a4d5-15ad146c258b - timeout=0
-swap /dev/sda7 /dev/urandom swap</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><refentrytitle>cryptsetup</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>mkswap</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>mke2fs</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- </para>
- </refsect1>
+<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><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><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><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><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><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><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><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><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><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><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