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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
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<!ENTITY VERSION "1.0">
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<!ENTITY COMMANDNAME "password-request">
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<!ENTITY TIMESTAMP "2008-09-04">
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<!ENTITY COMMANDNAME "mandos-client">
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<!ENTITY TIMESTAMP "2012-07-23">
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<!ENTITY % common SYSTEM "../common.ent">
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<refentry xmlns:xi="http://www.w3.org/2001/XInclude">
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<title>Mandos Manual</title>
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<!-- Nwalsh’s docbook scripts use this to generate the footer: -->
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<!-- NWalsh’s docbook scripts use this to generate the footer: -->
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<productname>Mandos</productname>
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<productnumber>&VERSION;</productnumber>
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<productnumber>&version;</productnumber>
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<date>&TIMESTAMP;</date>
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<firstname>Björn</firstname>
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<surname>Påhlsson</surname>
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<email>belorn@fukt.bsnet.se</email>
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<email>belorn@recompile.se</email>
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<firstname>Teddy</firstname>
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<surname>Hogeborn</surname>
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<email>teddy@fukt.bsnet.se</email>
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<email>teddy@recompile.se</email>
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<holder>Teddy Hogeborn</holder>
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<holder>Björn Påhlsson</holder>
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<xi:include href="../legalnotice.xml"/>
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<refentrytitle>&COMMANDNAME;</refentrytitle>
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<manvolnum>8mandos</manvolnum>
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</refsynopsisdiv>
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<refsect1 id="description">
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<title>DESCRIPTION</title>
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<command>&COMMANDNAME;</command> is a client program that
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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 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 or a TERM signal is received.
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to get a password. In slightly more detail, this client program
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brings up network interfaces, uses the interfaces’ IPv6
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link-local addresses to get network connectivity, uses Zeroconf
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to find servers on the local network, and communicates with
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servers using TLS with an OpenPGP key to ensure authenticity and
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confidentiality. This client program keeps running, trying all
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servers on the network, until it receives a satisfactory reply
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or a TERM signal. After all servers have been tried, all
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servers are periodically retried. If no servers are found it
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will wait indefinitely for new servers to appear.
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The network interfaces are selected like this: If any interfaces
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are specified using the <option>--interface</option> option,
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those interface are used. Otherwise,
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<command>&COMMANDNAME;</command> will use all interfaces that
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are not loopback interfaces, are not point-to-point interfaces,
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are capable of broadcasting and do not have the NOARP flag (see
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<citerefentry><refentrytitle>netdevice</refentrytitle>
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<manvolnum>7</manvolnum></citerefentry>). (If the
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<option>--connect</option> option is used, point-to-point
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interfaces and non-broadcast interfaces are accepted.) If any
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used interfaces are not up and running, they are first taken up
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(and later taken down again on program exit).
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Before network interfaces are selected, all <quote>network
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hooks</quote> are run; see <xref linkend="network-hooks"/>.
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This program is not meant to be run directly; it is really meant
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<term><option>--interface=
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<replaceable>NAME</replaceable></option></term>
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<term><option>--interface=<replaceable
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>NAME</replaceable><arg rep='repeat'>,<replaceable
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>NAME</replaceable></arg></option></term>
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<replaceable>NAME</replaceable></option></term>
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<replaceable>NAME</replaceable><arg rep='repeat'>,<replaceable
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>NAME</replaceable></arg></option></term>
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Network interface that will be brought up and scanned for
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Mandos servers to connect to. The default it
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<quote><literal>eth0</literal></quote>.
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If the <option>--connect</option> option is used, this
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specifies the interface to use to connect to the address
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Comma separated list of network interfaces that will be
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brought up and scanned for Mandos servers to connect to.
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The default is the empty string, which will automatically
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use all appropriate interfaces.
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If the <option>--connect</option> option is used, and
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exactly one interface name is specified (except
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<quote><literal>none</literal></quote>), this specifies
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the interface to use to connect to the address given.
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Note that since this program will normally run in the
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initial RAM disk environment, the interface must be an
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interface which exists at that stage. Thus, the interface
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can normally not be a pseudo-interface such as
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<quote>br0</quote> or <quote>tun0</quote>; such interfaces
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will not exist until much later in the boot process, and
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can not be used by this program, unless created by a
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<quote>network hook</quote> — see <xref
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linkend="network-hooks"/>.
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<replaceable>NAME</replaceable> can be the string
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<quote><literal>none</literal></quote>; this will make
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<command>&COMMANDNAME;</command> not bring up
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<emphasis>any</emphasis> interfaces specified
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<emphasis>after</emphasis> this string. This is not
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recommended, and only meant for advanced users.
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<term><option>--delay=<replaceable
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>SECONDS</replaceable></option></term>
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After bringing a network interface up, the program waits
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for the interface to arrive in a <quote>running</quote>
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state before proceeding. During this time, the kernel log
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level will be lowered to reduce clutter on the system
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console, alleviating any other plugins which might be
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using the system console. This option sets the upper
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limit of seconds to wait. The default is 2.5 seconds.
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<term><option>--retry=<replaceable
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>SECONDS</replaceable></option></term>
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All Mandos servers are tried repeatedly until a password
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is received. This value specifies, in seconds, how long
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between each successive try <emphasis>for the same
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server</emphasis>. The default is 10 seconds.
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<term><option>--network-hook-dir=<replaceable
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>DIR</replaceable></option></term>
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Network hook directory. The default directory is
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<quote><filename class="directory"
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>/lib/mandos/network-hooks.d</filename></quote>.
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<term><option>--debug</option></term>
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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 (<citerefentry>
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at all. This is why a separate plugin runner (<citerefentry>
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<refentrytitle>plugin-runner</refentrytitle>
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<manvolnum>8mandos</manvolnum></citerefentry>) is used to run
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both this program and others in in parallel,
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<emphasis>one</emphasis> of which (<citerefentry>
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<refentrytitle>password-prompt</refentrytitle>
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<manvolnum>8mandos</manvolnum></citerefentry>) does that, which
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will be run in parallel to this one by the plugin runner.
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<manvolnum>8mandos</manvolnum></citerefentry>) will prompt for
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passwords on the system console.
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<refsect1 id="network-hooks">
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<title>NETWORK HOOKS</title>
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If a network interface like a bridge or tunnel is required to
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find a Mandos server, this requires the interface to be up and
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running before <command>&COMMANDNAME;</command> starts looking
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for Mandos servers. This can be accomplished by creating a
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<quote>network hook</quote> program, and placing it in a special
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Before the network is used (and again before program exit), any
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runnable programs found in the network hook directory are run
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with the argument <quote><literal>start</literal></quote> or
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<quote><literal>stop</literal></quote>. This should bring up or
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down, respectively, any network interface which
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<command>&COMMANDNAME;</command> should use.
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<refsect2 id="hook-requirements">
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<title>REQUIREMENTS</title>
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A network hook must be an executable file, and its name must
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consist entirely of upper and lower case letters, digits,
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underscores, periods, and hyphens.
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A network hook will receive one argument, which can be one of
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<term><literal>start</literal></term>
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This should make the network hook create (if necessary)
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and bring up a network interface.
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<term><literal>stop</literal></term>
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This should make the network hook take down a network
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interface, and delete it if it did not exist previously.
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<term><literal>files</literal></term>
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This should make the network hook print, <emphasis>one
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file per line</emphasis>, all the files needed for it to
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run. (These files will be copied into the initial RAM
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filesystem.) Typical use is for a network hook which is
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a shell script to print its needed binaries.
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It is not necessary to print any non-executable files
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already in the network hook directory, these will be
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copied implicitly if they otherwise satisfy the name
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<term><literal>modules</literal></term>
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This should make the network hook print, <emphasis>on
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separate lines</emphasis>, all the kernel modules needed
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for it to run. (These modules will be copied into the
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initial RAM filesystem.) For instance, a tunnel
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<quote><literal>tun</literal></quote> module.
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The network hook will be provided with a number of environment
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<term><envar>MANDOSNETHOOKDIR</envar></term>
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The network hook directory, specified to
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<command>&COMMANDNAME;</command> by the
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<option>--network-hook-dir</option> option. Note: this
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should <emphasis>always</emphasis> be used by the
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network hook to refer to itself or any files in the hook
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directory it may require.
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<term><envar>DEVICE</envar></term>
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The network interfaces, as specified to
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<command>&COMMANDNAME;</command> by the
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<option>--interface</option> option, combined to one
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string and separated by commas. If this is set, and
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does not contain the interface a hook will bring up,
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there is no reason for a hook to continue.
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<term><envar>MODE</envar></term>
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This will be the same as the first argument;
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i.e. <quote><literal>start</literal></quote>,
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<quote><literal>stop</literal></quote>,
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<quote><literal>files</literal></quote>, or
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<quote><literal>modules</literal></quote>.
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<term><envar>VERBOSITY</envar></term>
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This will be the <quote><literal>1</literal></quote> if
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the <option>--debug</option> option is passed to
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<command>&COMMANDNAME;</command>, otherwise
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<quote><literal>0</literal></quote>.
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<term><envar>DELAY</envar></term>
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This will be the same as the <option>--delay</option>
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option passed to <command>&COMMANDNAME;</command>. Is
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only set if <envar>MODE</envar> is
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<quote><literal>start</literal></quote> or
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<quote><literal>stop</literal></quote>.
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<term><envar>CONNECT</envar></term>
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This will be the same as the <option>--connect</option>
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option passed to <command>&COMMANDNAME;</command>. Is
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only set if <option>--connect</option> is passed and
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<envar>MODE</envar> is
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<quote><literal>start</literal></quote> or
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<quote><literal>stop</literal></quote>.
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A hook may not read from standard input, and should be
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restrictive in printing to standard output or standard error
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unless <varname>VERBOSITY</varname> is
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<quote><literal>1</literal></quote>.
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<refsect1 id="files">
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<title>FILES</title>
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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
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and will stop giving out the encrypted data. Therefore, it is
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important to set the timeout and checker interval values tightly
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on the server. See <citerefentry><refentrytitle
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and communicate with the server. To safeguard against this, the
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server is supposed to notice the client disappearing and stop
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giving out the encrypted data. Therefore, it is important to
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set the timeout and checker interval values tightly on the
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server. See <citerefentry><refentrytitle
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>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>.