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Committer: Teddy Hogeborn
Date: 2008-09-03 17:11:32 UTC
Revision ID: teddy@fukt.bsnet.se-20080903171132-usevhlf0gi9rxqc3

* plugins.d/password-request.c (init_gnutls_global): Improved wording
                                                     in debug message.
                                                     Bug fix: Make
                                                     debug message
                                                     print to stderr,
                                                     not stdout.

* plugins.d/password-request.xml (SECURITY): Add text.

files added:
.bzrignore

COPYING

initramfs-tools-hook

initramfs-tools-hook-conf

initramfs-tools-script

legalnotice.xml

mandos-clients.conf.xml

mandos-keygen

mandos-keygen.xml

mandos-options.xml

mandos.conf.xml

mandos.xml

overview.xml

plugin-runner.xml

plugins.d/password-prompt.xml

plugins.d/password-request.xml

plugins.d/usplash

files removed:
ca.pem

cert.pem

client-cert.pem

client-key.pem

crl.pem

key.pem

files renamed:
server.py => mandos

server.conf => mandos.conf

plugbasedclient.c => plugin-runner.c

plugins.d/passprompt.c => plugins.d/password-prompt.c

plugins.d/mandosclient.c => plugins.d/password-request.c

files modified:
Makefile

TODO

clients.conf

Show diffs side-by-side

added added

removed removed

plugins.d/password-request.xml

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"

"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [

<!ENTITY VERSION "1.0">

<!ENTITY COMMANDNAME "password-request">

<!ENTITY TIMESTAMP "2008-09-03">

<title>Mandos Manual</title>

<productname>Mandos</productname>

<productnumber>&VERSION;</productnumber>

<date>&TIMESTAMP;</date>

<firstname>Björn</firstname>

<surname>Påhlsson</surname>

<email>belorn@fukt.bsnet.se</email>

</address>

</author>

<firstname>Teddy</firstname>

<surname>Hogeborn</surname>

<email>teddy@fukt.bsnet.se</email>

</address>

</author>

</authorgroup>

<holder>Teddy Hogeborn</holder>

<holder>Björn Påhlsson</holder>

</copyright>

<xi:include href="../legalnotice.xml"/>

</refentryinfo>

<refentrytitle>&COMMANDNAME;</refentrytitle>

<manvolnum>8mandos</manvolnum>

</refmeta>

<refname><command>&COMMANDNAME;</command></refname>

Client for mandos

</refpurpose>

</refnamediv>

<command>&COMMANDNAME;</command>

<group>

<arg choice="plain"><option>--connect

<replaceable>IPADDR</replaceable><literal>:</literal

><replaceable>PORT</replaceable></option></arg>

<arg choice="plain"><option>-c

<replaceable>IPADDR</replaceable><literal>:</literal

><replaceable>PORT</replaceable></option></arg>

</group>

<sbr/>

<group>

<arg choice="plain"><option>--keydir

<replaceable>DIRECTORY</replaceable></option></arg>

<arg choice="plain"><option>-d

<replaceable>DIRECTORY</replaceable></option></arg>

</group>

<sbr/>

<group>

<arg choice="plain"><option>--interface

<arg choice="plain"><option>-i

</group>

<sbr/>

<group>

<arg choice="plain"><option>--pubkey

<arg choice="plain"><option>-p

</group>

<sbr/>

<group>

<arg choice="plain"><option>--seckey

<arg choice="plain"><option>-s

</group>

<sbr/>

<arg>

<option>--priority <replaceable>STRING</replaceable></option>

</arg>

<sbr/>

<arg>

</arg>

<sbr/>

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<arg>

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<option>--debug</option>

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</arg>

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</cmdsynopsis>

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<command>&COMMANDNAME;</command>

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</group>

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</cmdsynopsis>

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<command>&COMMANDNAME;</command>

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<arg choice="plain"><option>--usage</option></arg>

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</cmdsynopsis>

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<command>&COMMANDNAME;</command>

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<arg choice="plain"><option>--version</option></arg>

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</group>

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</cmdsynopsis>

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</refsynopsisdiv>

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<title>DESCRIPTION</title>

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<para>

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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 recieved.

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</para>

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<para>

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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 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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</para>

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</refsect1>

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<title>PURPOSE</title>

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<para>

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The purpose of this is to enable <emphasis>remote and unattended

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rebooting</emphasis> of client host computer with an

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<emphasis>encrypted root file system</emphasis>. See <xref

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linkend="overview"/> for details.

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</para>

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</refsect1>

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<title>OPTIONS</title>

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<para>

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This program is commonly not invoked from the command line; it

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is normally started by the <application>Mandos</application>

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plugin runner, see <citerefentry><refentrytitle

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>plugin-runner</refentrytitle><manvolnum>8mandos</manvolnum>

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</citerefentry>. Any command line options this program accepts

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are therefore normally provided by the plugin runner, and not

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directly.

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</para>

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<term><option>--connect=<replaceable

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>ADDRESS</replaceable><literal>:</literal><replaceable

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>PORT</replaceable></option></term>

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<term><option>-c

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<replaceable>ADDRESS</replaceable><literal>:</literal

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><replaceable>PORT</replaceable></option></term>

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<para>

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Do not use Zeroconf to locate servers. Connect directly

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to only one specified <application>Mandos</application>

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server. Note that an IPv6 address has colon characters in

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it, so the <emphasis>last</emphasis> colon character is

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assumed to separate the address from the port number.

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</para>

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<para>

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This option is normally only useful for testing and

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debugging.

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</para>

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</listitem>

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</varlistentry>

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<term><option>--keydir=<replaceable

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>DIRECTORY</replaceable></option></term>

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<term><option>-d

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<replaceable>DIRECTORY</replaceable></option></term>

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<para>

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Directory to read the OpenPGP key files

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<filename>pubkey.txt</filename> and

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<filename>seckey.txt</filename> from. The default is

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<filename>/conf/conf.d/mandos</filename> (in the initial

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<acronym>RAM</acronym> disk environment).

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</para>

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</listitem>

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</varlistentry>

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<term><option>--interface=

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<term><option>-i

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<para>

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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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</para>

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<para>

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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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given.

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</para>

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</listitem>

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</varlistentry>

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<term><option>--pubkey=<replaceable

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>FILE</replaceable></option></term>

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<term><option>-p

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<para>

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OpenPGP public key file base name. This will be combined

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with the directory from the <option>--keydir</option>

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option to form an absolute file name. The default name is

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<quote><literal>pubkey.txt</literal></quote>.

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</para>

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</listitem>

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</varlistentry>

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<term><option>--seckey=<replaceable

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>FILE</replaceable></option></term>

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<term><option>-s

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<para>

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OpenPGP secret key file base name. This will be combined

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with the directory from the <option>--keydir</option>

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option to form an absolute file name. The default name is

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<quote><literal>seckey.txt</literal></quote>.

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</para>

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</listitem>

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</varlistentry>

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<term><option>--priority=<replaceable

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>STRING</replaceable></option></term>

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<xi:include href="../mandos-options.xml"

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xpointer="priority"/>

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</listitem>

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</varlistentry>

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<term><option>--dh-bits=<replaceable

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>BITS</replaceable></option></term>

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<para>

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Sets the number of bits to use for the prime number in the

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TLS Diffie-Hellman key exchange. Default is 1024.

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</para>

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</listitem>

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</varlistentry>

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<term><option>--debug</option></term>

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<para>

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Enable debug mode. This will enable a lot of output to

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standard error about what the program is doing. The

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program will still perform all other functions normally.

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</para>

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<para>

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It will also enable debug mode in the Avahi and GnuTLS

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libraries, making them print large amounts of debugging

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output.

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</para>

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</listitem>

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</varlistentry>

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<para>

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Gives a help message about options and their meanings.

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</para>

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</listitem>

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</varlistentry>

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<term><option>--usage</option></term>

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<para>

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Gives a short usage message.

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</para>

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</listitem>

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</varlistentry>

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<term><option>--version</option></term>

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<para>

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Prints the program version.

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</para>

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</listitem>

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</varlistentry>

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</variablelist>

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</refsect1>

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<title>OVERVIEW</title>

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<xi:include href="../overview.xml"/>

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<para>

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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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</para>

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<para>

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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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</para>

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</refsect1>

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<title>EXIT STATUS</title>

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<para>

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This program will exit with a successful (zero) exit status if a

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server could be found and the password received from it could be

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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>Mandos</application> servers as they appear, trying

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to get a decryptable password.

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</para>

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</refsect1>

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<title>ENVIRONMENT</title>

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<para>

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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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</citerefentry>.

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</para>

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</refsect1>

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<title>FILES</title>

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<term><filename>/conf/conf.d/mandos/pubkey.txt</filename

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></term>

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<term><filename>/conf/conf.d/mandos/seckey.txt</filename

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></term>

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<para>

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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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</para>

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</listitem>

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</varlistentry>

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</variablelist>

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</refsect1>

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<title>EXAMPLE</title>

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<para>

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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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</para>

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<para>

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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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</para>

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<para>

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<userinput>&COMMANDNAME;</userinput>

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</para>

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</informalexample>

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<para>

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Search for Mandos servers on another interface:

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</para>

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<para>

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<userinput>&COMMANDNAME; --interface eth1</userinput>

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</para>

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</informalexample>

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<para>

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Run in debug mode, and use a custom key directory:

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</para>

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<para>

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<userinput>&COMMANDNAME; --debug --keydir keydir</userinput>

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</para>

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</informalexample>

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<para>

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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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</para>

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<para>

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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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</para>

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</informalexample>

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</refsect1>

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<title>SECURITY</title>

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<para>

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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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</para>

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<para>

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To use this program for its intended purpose (see <xref

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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

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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

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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,

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however, is stored unencrypted on the client side in its initial

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<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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to read that file.

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</para>

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<para>

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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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>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>.

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</para>

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<para>

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<emphasis>Note</emphasis>: This makes it impossible to have

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<application >Mandos</application> clients which dual-boot to

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another operating system which does <emphasis>not</emphasis> run

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a <application>Mandos</application> client.

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</para>

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</refsect1>

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<para>

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<citerefentry><refentrytitle>mandos</refentrytitle>

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<manvolnum>8</manvolnum></citerefentry>,

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<citerefentry><refentrytitle>password-prompt</refentrytitle>

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<manvolnum>8mandos</manvolnum></citerefentry>,

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<citerefentry><refentrytitle>plugin-runner</refentrytitle>

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<manvolnum>8mandos</manvolnum></citerefentry>

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</para>

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<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>

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</para></listitem>

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<ulink url="http://www.avahi.org/">Avahi</ulink>

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</para></listitem>

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<ulink

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url="http://www.gnu.org/software/gnutls/">GnuTLS</ulink>

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</para></listitem>

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<ulink

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url="http://www.gnupg.org/related_software/gpgme/"

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>GPGME</ulink>

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</para></listitem>

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<citation>RFC 4880: <citetitle>OpenPGP Message

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Format</citetitle></citation>

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</para></listitem>

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<citation>RFC 5081: <citetitle>Using OpenPGP Keys for

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Transport Layer Security</citetitle></citation>

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</para></listitem>

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<citation>RFC 4291: <citetitle>IP Version 6 Addressing

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Architecture</citetitle>, section 2.5.6, Link-Local IPv6

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Unicast Addresses</citation>

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</para></listitem>

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</itemizedlist>

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</refsect1>

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</refentry>

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