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Committer: Teddy Hogeborn
Date: 2008-09-01 16:53:17 UTC
Revision ID: teddy@fukt.bsnet.se-20080901165317-77dccp81zyqimt2j

* plugin-runner.c (add_environment): Override existing environment
                                     variables when asked to do so.
                                     All callers changed.
  (main): Removed old argp.args_doc string.  Parse argument file
          before normal command line arguments.  Use ARGP_IN_ORDER
          flag in both calls to argp_parse.  Do not strdup() strings
          to be sent to add_environment().

* plugin-runner.xml (OPTIONS): Document "--global-env" and "--envs-for".
  (FILES): Note that the config file is parsed before the command line
           options.

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 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

mandos.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 "mandos">

<!ENTITY TIMESTAMP "2008-09-01">

<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>

</refmeta>

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

Gives encrypted passwords to authenticated Mandos clients

</refpurpose>

</refnamediv>

<command>&COMMANDNAME;</command>

<group>

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

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

</group>

<sbr/>

<group>

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

<replaceable>ADDRESS</replaceable></option></arg>

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

<replaceable>ADDRESS</replaceable></option></arg>

</group>

<sbr/>

<group>

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

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

</group>

<sbr/>

<arg><option>--priority

<replaceable>PRIORITY</replaceable></option></arg>

<sbr/>

<arg><option>--servicename

<sbr/>

<arg><option>--configdir

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

<sbr/>

<arg><option>--debug</option></arg>

</cmdsynopsis>

<command>&COMMANDNAME;</command>

</group>

</cmdsynopsis>

<command>&COMMANDNAME;</command>

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

</cmdsynopsis>

<command>&COMMANDNAME;</command>

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

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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 server daemon which

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handles incoming request for passwords for a pre-defined list of

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client host computers. The Mandos server uses Zeroconf to

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announce itself on the local network, and uses TLS to

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communicate securely with and to authenticate the clients. The

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Mandos server uses IPv6 to allow Mandos clients to use IPv6

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link-local addresses, since the clients will probably not have

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any other addresses configured (see <xref linkend="overview"/>).

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Any authenticated client is then given the stored pre-encrypted

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password for that specific client.

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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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Show a help message and exit

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</para>

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</listitem>

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</varlistentry>

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<term><option>--interface</option>

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

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</listitem>

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</varlistentry>

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<term><option>--address

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<replaceable>ADDRESS</replaceable></option></term>

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<term><option>-a

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<replaceable>ADDRESS</replaceable></option></term>

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

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</listitem>

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</varlistentry>

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<term><option>--port

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<term><option>-p

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

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</listitem>

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</varlistentry>

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<term><option>--check</option></term>

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<para>

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Run the server’s self-tests. This includes any unit

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tests, etc.

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

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</listitem>

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</varlistentry>

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

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PRIORITY</replaceable></option></term>

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

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</listitem>

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</varlistentry>

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<term><option>--servicename

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

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xpointer="servicename"/>

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</listitem>

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</varlistentry>

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<term><option>--configdir

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

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<para>

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Directory to search for configuration files. Default is

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<quote><literal>/etc/mandos</literal></quote>. See

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<citerefentry><refentrytitle>mandos.conf</refentrytitle>

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<refentrytitle>mandos-clients.conf</refentrytitle>

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<manvolnum>5</manvolnum></citerefentry>.

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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 and exit.

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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 server part. It is a normal server program

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and will run in a normal system environment, not in an initial

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<acronym>RAM</acronym> disk environment.

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</para>

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</refsect1>

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<title>NETWORK PROTOCOL</title>

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<para>

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The Mandos server announces itself as a Zeroconf service of type

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<quote><literal>_mandos._tcp</literal></quote>. The Mandos

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client connects to the announced address and port, and sends a

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line of text where the first whitespace-separated field is the

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protocol version, which currently is

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<quote><literal>1</literal></quote>. The client and server then

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start a TLS protocol handshake with a slight quirk: the Mandos

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server program acts as a TLS <quote>client</quote> while the

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connecting Mandos client acts as a TLS <quote>server</quote>.

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The Mandos client must supply an OpenPGP certificate, and the

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fingerprint of this certificate is used by the Mandos server to

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look up (in a list read from <filename>clients.conf</filename>

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at start time) which binary blob to give the client. No other

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authentication or authorization is done by the server.

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</para>

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<table>

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<title>Mandos Protocol (Version 1)</title><tgroup cols="3"><thead>

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<row>

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<entry>Mandos Client</entry>

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<entry>Direction</entry>

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<entry>Mandos Server</entry>

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</row>

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</thead><tbody>

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<row>

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<entry>Connect</entry>

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</row>

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<row>

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</row>

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<row>

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<entry>TLS handshake <emphasis>as TLS <quote>server</quote>

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</emphasis></entry>

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<entry>TLS handshake <emphasis>as TLS <quote>client</quote>

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</emphasis></entry>

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</row>

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<row>

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<entry>OpenPGP public key (part of TLS handshake)</entry>

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</row>

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<row>

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<entry>Binary blob (client will assume OpenPGP data)</entry>

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</row>

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<row>

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<entry>Close</entry>

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</row>

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</tbody></tgroup></table>

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</refsect1>

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<title>CHECKING</title>

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<para>

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The server will, by default, continually check that the clients

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are still up. If a client has not been confirmed as being up

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for some time, the client is assumed to be compromised and is no

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longer eligible to receive the encrypted password. The timeout,

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checker program, and interval between checks can be configured

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both globally and per client; see <citerefentry>

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<refentrytitle>mandos-clients.conf</refentrytitle>

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<manvolnum>5</manvolnum></citerefentry>.

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</para>

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</refsect1>

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<title>LOGGING</title>

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<para>

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The server will send log message with various severity levels to

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<filename>/dev/log</filename>. With the

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<option>--debug</option> option, it will log even more messages,

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and also show them on the console.

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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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The server will exit with a non-zero exit status only when a

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critical error is encountered.

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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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To start the configured checker (see <xref

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linkend="checking"/>), the server uses

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<filename>/bin/sh</filename>, which in turn uses

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<varname>PATH</varname> to search for matching commands if

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an absolute path is not given. See <citerefentry>

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</citerefentry>.

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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>FILES</title>

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<para>

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Use the <option>--configdir</option> option to change where

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<command>&COMMANDNAME;</command> looks for its configurations

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files. The default file names are listed here.

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</para>

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<term><filename>/etc/mandos/mandos.conf</filename></term>

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<para>

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Server-global settings. See

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<citerefentry><refentrytitle>mandos.conf</refentrytitle>

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<manvolnum>5</manvolnum></citerefentry> for details.

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</para>

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</listitem>

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</varlistentry>

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<term><filename>/etc/mandos/clients.conf</filename></term>

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<para>

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List of clients and client-specific settings. See

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<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>

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<manvolnum>5</manvolnum></citerefentry> for details.

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</para>

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</listitem>

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</varlistentry>

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<term><filename>/var/run/mandos/mandos.pid</filename></term>

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<para>

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The file containing the process id of

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<command>&COMMANDNAME;</command>.

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</para>

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</listitem>

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</varlistentry>

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<para>

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The Unix domain socket to where local syslog messages are

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sent.

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</para>

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</listitem>

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</varlistentry>

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<para>

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This is used to start the configured checker command for

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each client. See <citerefentry>

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<refentrytitle>mandos-clients.conf</refentrytitle>

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<manvolnum>5</manvolnum></citerefentry> for details.

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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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<para>

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This server might, on especially fatal errors, emit a Python

421

backtrace. This could be considered a feature.

422

</para>

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<para>

424

Currently, if a client is declared <quote>invalid</quote> due to

425

having timed out, the server does not record this fact onto

426

permanent storage. This has some security implications, see

427

<xref linkend="CLIENTS"/>.

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</para>

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<para>

430

There is currently no way of querying the server of the current

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status of clients, other than analyzing its <systemitem

432

class="service">syslog</systemitem> output.

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</para>

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<para>

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There is no fine-grained control over logging and debug output.

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</para>

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<para>

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Debug mode is conflated with running in the foreground.

439

</para>

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<para>

441

The console log messages does not show a timestamp.

442

</para>

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</refsect1>

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<title>EXAMPLE</title>

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<para>

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Normal invocation needs no options:

450

</para>

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<para>

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<userinput>&COMMANDNAME;</userinput>

453

</para>

454

</informalexample>

455

456

<para>

457

Run the server in debug mode, read configuration files from

458

the <filename>~/mandos</filename> directory, and use the

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Zeroconf service name <quote>Test</quote> to not collide with

460

any other official Mandos server on this host:

461

</para>

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<para>

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<userinput>&COMMANDNAME; --debug --configdir ~/mandos --servicename Test</userinput>

466

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</para>

468

</informalexample>

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<para>

471

Run the server normally, but only listen to one interface and

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only on the link-local address on that interface:

473

</para>

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<para>

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477

<userinput>&COMMANDNAME; --interface eth7 --address fe80::aede:48ff:fe71:f6f2</userinput>

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</para>

480

</informalexample>

481

</refsect1>

482

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484

<title>SECURITY</title>

485

486

<title>SERVER</title>

487

<para>

488

Running this <command>&COMMANDNAME;</command> server program

489

should not in itself present any security risk to the host

490

computer running it. The program does not need any special

491

privileges to run, and is designed to run as a non-root user.

492

</para>

493

</refsect2>

494

495

<title>CLIENTS</title>

496

<para>

497

The server only gives out its stored data to clients which

498

does have the OpenPGP key of the stored fingerprint. This is

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guaranteed by the fact that the client sends its OpenPGP

500

public key in the TLS handshake; this ensures it to be

501

genuine. The server computes the fingerprint of the key

502

itself and looks up the fingerprint in its list of

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clients. The <filename>clients.conf</filename> file (see

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<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>

505

<manvolnum>5</manvolnum></citerefentry>)

506

<emphasis>must</emphasis> be made non-readable by anyone

507

except the user running the server.

508

</para>

509

<para>

510

As detailed in <xref linkend="checking"/>, the status of all

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client computers will continually be checked and be assumed

512

compromised if they are gone for too long.

513

</para>

514

<para>

515

If a client is compromised, its downtime should be duly noted

516

by the server which would therefore declare the client

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invalid. But if the server was ever restarted, it would

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re-read its client list from its configuration file and again

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regard all clients therein as valid, and hence eligible to

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receive their passwords. Therefore, be careful when

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restarting servers if it is suspected that a client has, in

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fact, been compromised by parties who may now be running a

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fake Mandos client with the keys from the non-encrypted

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initial <acronym>RAM</acronym> image of the client host. What

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should be done in that case (if restarting the server program

526

really is necessary) is to stop the server program, edit the

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configuration file to omit any suspect clients, and restart

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the server program.

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</para>

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<para>

531

For more details on client-side security, see

532

<citerefentry><refentrytitle>password-request</refentrytitle>

533

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

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</para>

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</refsect2>

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</refsect1>

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<para>

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<refentrytitle>mandos-clients.conf</refentrytitle>

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<refentrytitle>mandos.conf</refentrytitle>

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<refentrytitle>password-request</refentrytitle>

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

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</citerefentry>

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</para>

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<term>

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

555

</term>

556

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<para>

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Zeroconf is the network protocol standard used by clients

559

for finding this Mandos server on the local network.

560

</para>

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</listitem>

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</varlistentry>

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<term>

565

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

566

</term>

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568

<para>

569

Avahi is the library this server calls to implement

570

Zeroconf service announcements.

571

</para>

572

</listitem>

573

</varlistentry>

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<term>

576

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

577

>GnuTLS</ulink>

578

</term>

579

580

<para>

581

GnuTLS is the library this server uses to implement TLS for

582

communicating securely with the client, and at the same time

583

confidently get the client’s public OpenPGP key.

584

</para>

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</listitem>

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</varlistentry>

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588

<term>

589

RFC 4291: <citetitle>IP Version 6 Addressing

590

Architecture</citetitle>

591

</term>

592

593

594

595

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

596

Addresses</citetitle></term>

597

598

</varlistentry>

599

600

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

601

Address</citetitle></term>

602

603

</varlistentry>

604

605

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

606

Addresses</citetitle></term>

607

608

<para>

609

The clients use IPv6 link-local addresses, which are

610

immediately usable since a link-local addresses is

611

automatically assigned to a network interfaces when it

612

is brought up.

613

</para>

614

</listitem>

615

</varlistentry>

616

</variablelist>

617

</listitem>

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</varlistentry>

619

620

<term>

621

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

622

Protocol Version 1.1</citetitle>

623

</term>

624

625

<para>

626

TLS 1.1 is the protocol implemented by GnuTLS.

627

</para>

628

</listitem>

629

</varlistentry>

630

631

<term>

632

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

633

</term>

634

635

<para>

636

The data sent to clients is binary encrypted OpenPGP data.

637

</para>

638

</listitem>

639

</varlistentry>

640

641

<term>

642

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

643

Security</citetitle>

644

</term>

645

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<para>

647

This is implemented by GnuTLS and used by this server so

648

that OpenPGP keys can be used.

649

</para>

650

</listitem>

651

</varlistentry>

652

</variablelist>

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</refsect1>

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</refentry>

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