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communicates with <citerefentry><refentrytitle
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>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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to get a password. It uses IPv6 link-local addresses to get
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network connectivity, Zeroconf to find the server, and TLS with
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an OpenPGP key to ensure authenticity and confidentiality. It
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network connectivity, Zeroconf to find servers, and TLS with an
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OpenPGP key to ensure authenticity and confidentiality. It
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keeps running, trying all servers on the network, until it
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receives a satisfactory reply.
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receives a satisfactory reply or a TERM signal is recieved.
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This program is not meant to be run directly; it is really meant
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to run as a plugin of the <application>Mandos</application>
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<citerefentry><refentrytitle>plugin-runner</refentrytitle>
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<manvolnum>8mandos</manvolnum></citerefentry>, which in turn
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runs as a <quote>keyscript</quote> specified in the
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<citerefentry><refentrytitle>crypttab</refentrytitle>
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<manvolnum>5</manvolnum></citerefentry> file.
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<manvolnum>8mandos</manvolnum></citerefentry>, which runs in the
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initial <acronym>RAM</acronym> disk environment because it is
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specified as a <quote>keyscript</quote> in the <citerefentry>
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<refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
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</citerefentry> file.
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<refsect1 id="overview">
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<title>OVERVIEW</title>
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<xi:include href="overview.xml"/>
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This program is the client part. It is a plugin started by
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<citerefentry><refentrytitle>plugin-runner</refentrytitle>
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<manvolnum>8mandos</manvolnum></citerefentry> which will run in
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an initial <acronym>RAM</acronym> disk environment.
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This program could, theoretically, be used as a keyscript in
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<filename>/etc/crypttab</filename>, but it would then be
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impossible to enter the encrypted root disk password at the
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console, since this program does not read from the console at
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all. This is why a separate plugin does that, which will be run
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in parallell to this one.
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<refsect1 id="options">
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<title>OPTIONS</title>
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<refsect1 id="overview">
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<title>OVERVIEW</title>
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<xi:include href="../overview.xml"/>
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This program is the client part. It is a plugin started by
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<citerefentry><refentrytitle>plugin-runner</refentrytitle>
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<manvolnum>8mandos</manvolnum></citerefentry> which will run in
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an initial <acronym>RAM</acronym> disk environment.
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This program could, theoretically, be used as a keyscript in
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<filename>/etc/crypttab</filename>, but it would then be
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impossible to enter a password for the encrypted root disk at
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the console, since this program does not read from the console
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at all. This is why a separate plugin does that, which will be
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run in parallell to this one by the plugin runner.
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<refsect1 id="exit_status">
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<title>EXIT STATUS</title>
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successfully decrypted and output on standard output. The
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program will exit with a non-zero exit status only if a critical
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error occurs. Otherwise, it will forever connect to new
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<application>Mandosservers</application> servers as they appear,
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trying to get a decryptable password.
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<!-- <refsect1 id="environment"> -->
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<!-- <title>ENVIRONMENT</title> -->
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<application>Mandos</application> servers as they appear, trying
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to get a decryptable password.
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<refsect1 id="environment">
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<title>ENVIRONMENT</title>
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This program does not use any environment variables, not even
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the ones provided by <citerefentry><refentrytitle
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>cryptsetup</refentrytitle><manvolnum>8</manvolnum>
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<term><filename>/conf/conf.d/mandos/pubkey.txt</filename
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<term><filename>/conf/conf.d/mandos/seckey.txt</filename
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OpenPGP public and private key files, in <quote>ASCII
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Armor</quote> format. These are the default file names,
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they can be changed with the <option>--pubkey</option> and
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<option>--seckey</option> options.
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<!-- <refsect1 id="bugs"> -->
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<!-- <title>BUGS</title> -->
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<!-- This program does not use any environment variables. -->
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<!-- </refsect1> -->
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<refsect1 id="example">
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<title>EXAMPLE</title>
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Note that normally, command line options will not be given
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directly, but via options for the Mandos <citerefentry
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><refentrytitle>plugin-runner</refentrytitle>
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<manvolnum>8mandos</manvolnum></citerefentry>.
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Normal invocation needs no options, if the network interface
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is <quote>eth0</quote>:
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<userinput>&COMMANDNAME;</userinput>
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Search for Mandos servers on another interface:
415
<!-- do not wrap this line -->
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<userinput>&COMMANDNAME; --interface eth1</userinput>
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Run in debug mode, and use a custom key directory:
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<!-- do not wrap this line -->
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<userinput>&COMMANDNAME; --debug --keydir keydir</userinput>
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Run in debug mode, with a custom key directory, and do not use
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Zeroconf to locate a server; connect directly to the IPv6
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address <quote><systemitem class="ipaddress"
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>2001:db8:f983:bd0b:30de:ae4a:71f2:f672</systemitem></quote>,
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port 4711, using interface eth2:
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<!-- do not wrap this line -->
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<userinput>&COMMANDNAME; --debug --keydir keydir --connect 2001:db8:f983:bd0b:30de:ae4a:71f2:f672:4711 --interface eth2</userinput>
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<refsect1 id="security">
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<title>SECURITY</title>
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This program is set-uid to root, but will switch back to the
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original user and group after bringing up the network interface.
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To use this program for its intended purpose (see <xref
453
linkend="purpose"/>), the password for the root file system will
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have to be given out to be stored in a server computer, after
455
having been encrypted using an OpenPGP key. This encrypted data
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which will be stored in a server can only be decrypted by the
457
OpenPGP key, and the data will only be given out to those
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clients who can prove they actually have that key. This key,
459
however, is stored unencrypted on the client side in its initial
460
<acronym>RAM</acronym> disk image file system. This is normally
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readable by all, but this is normally fixed during installation
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of this program; file permissions are set so that no-one is able
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The only remaining weak point is that someone with physical
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access to the client hard drive might turn off the client
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computer, read the OpenPGP keys directly from the hard drive,
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and communicate with the server. The defense against this is
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that the server is supposed to notice the client disappearing
471
and will stop giving out the encrypted data. Therefore, it is
472
important to set the timeout and checker interval values tightly
473
on the server. See <citerefentry><refentrytitle
474
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
477
<emphasis>Note</emphasis>: This makes it impossible to have
478
<application >Mandos</application> clients which dual-boot to
479
another operating system which does <emphasis>not</emphasis> run
480
a <application>Mandos</application> client.