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Committer: Teddy Hogeborn
Date: 2008-09-06 16:11:50 UTC
Revision ID: teddy@fukt.bsnet.se-20080906161150-1umb8yz6a29zxg28

* Makefile (install-client): Add "/etc/plugins.d/README".
(uninstall-client): Remove "/etc/plugins.d/README".

* etc-plugins.d-README: New file.

files added:
.bzrignore

COPYING

README

default-mandos

etc-plugins.d-README

init.d-mandos

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

mandos.conf.xml

mandos.xml

overview.xml

plugin-runner.conf

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

plugins.d/Makefile

files renamed:
mandos-clients.conf => clients.conf

server.py => mandos

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

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 "2008-09-04">

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

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

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

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

><replaceable>PORT</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/>

<arg>

<option>--debug</option>

</arg>

</cmdsynopsis>

<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 received.

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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>--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 name. The default name is

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

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></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 name. The default name is

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

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></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 (<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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</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.

331

</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>

340

</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>:

382

</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 (and connect to them) using another

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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:

400

</para>

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<para>

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<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt</userinput>

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</para>

407

</informalexample>

408

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<para>

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Run in debug mode, with a custom key, and do not use Zeroconf

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to locate a server; connect directly to the IPv6 address

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<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 --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt --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 (and presumably non-privileged) user and group after

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bringing up the network interface.

431

</para>

432

<para>

433

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

437

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

439

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

443

of this program; file permissions are set so that no-one is able

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to read that file.

445

</para>

446

<para>

447

The only remaining weak point is that someone with physical

448

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,

450

and communicate with the server. The defense against this is

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that the server is supposed to notice the client disappearing

452

and will stop giving out the encrypted data. Therefore, it is

453

important to set the timeout and checker interval values tightly

454

on the server. See <citerefentry><refentrytitle

455

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

456

</para>

457

<para>

458

It will also help if the checker program on the server is

459

configured to request something from the client which can not be

460

spoofed by someone else on the network, unlike unencrypted

461

<acronym>ICMP</acronym> echo (<quote>ping</quote>) replies.

462

</para>

463

<para>

464

<emphasis>Note</emphasis>: This makes it completely insecure to

465

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

466

to another operating system which is <emphasis>not</emphasis>

467

trusted to keep the initial <acronym>RAM</acronym> disk image

468

confidential.

469

</para>

470

</refsect1>

471

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<para>

475

<citerefentry><refentrytitle>cryptsetup</refentrytitle>

476

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

477

<citerefentry><refentrytitle>crypttab</refentrytitle>

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<manvolnum>5</manvolnum></citerefentry>,

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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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<term>

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

490

</term>

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<para>

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Zeroconf is the network protocol standard used for finding

494

Mandos servers on the local network.

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</para>

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</listitem>

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</varlistentry>

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<term>

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

501

</term>

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<para>

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Avahi is the library this program calls to find Zeroconf

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services.

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</para>

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</listitem>

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</varlistentry>

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<term>

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

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>GnuTLS</ulink>

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</term>

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<para>

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GnuTLS is the library this client uses to implement TLS for

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communicating securely with the server, and at the same time

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send the public OpenPGP key to the server.

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</para>

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</listitem>

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</varlistentry>

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<term>

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

525

>GPGME</ulink>

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</term>

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<para>

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GPGME is the library used to decrypt the OpenPGP data sent

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by the server.

531

</para>

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</listitem>

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</varlistentry>

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<term>

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RFC 4291: <citetitle>IP Version 6 Addressing

537

Architecture</citetitle>

538

</term>

539

540

541

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<term>Section 2.2: <citetitle>Text Representation of

543

Addresses</citetitle></term>

544

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</varlistentry>

546

547

<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6

548

Address</citetitle></term>

549

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</varlistentry>

551

552

<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast

553

Addresses</citetitle></term>

554

555

<para>

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This client uses IPv6 link-local addresses, which are

557

immediately usable since a link-local addresses is

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automatically assigned to a network interfaces when it

559

is brought up.

560

</para>

561

</listitem>

562

</varlistentry>

563

</variablelist>

564

</listitem>

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</varlistentry>

566

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<term>

568

RFC 4346: <citetitle>The Transport Layer Security (TLS)

569

Protocol Version 1.1</citetitle>

570

</term>

571

572

<para>

573

TLS 1.1 is the protocol implemented by GnuTLS.

574

</para>

575

</listitem>

576

</varlistentry>

577

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<term>

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RFC 4880: <citetitle>OpenPGP Message Format</citetitle>

580

</term>

581

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<para>

583

The data received from the server is binary encrypted

584

OpenPGP data.

585

</para>

586

</listitem>

587

</varlistentry>

588

589

<term>

590

RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer

591

Security</citetitle>

592

</term>

593

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<para>

595

This is implemented by GnuTLS and used by this program so

596

that OpenPGP keys can be used.

597

</para>

598

</listitem>

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</varlistentry>

600

</variablelist>

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</refsect1>

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</refentry>

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