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<!ENTITY VERSION "1.0">
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<!ENTITY COMMANDNAME "mandos">
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<!ENTITY TIMESTAMP "2022-04-24">
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<!ENTITY % common SYSTEM "common.ent">
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<refentry xmlns:xi="http://www.w3.org/2001/XInclude">
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<title>Mandos Manual</title>
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<!-- NWalsh’s docbook scripts use this to generate the footer: -->
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<productname>Mandos</productname>
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<productnumber>&version;</productnumber>
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<date>&TIMESTAMP;</date>
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<title>&COMMANDNAME;</title>
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<!-- NWalsh's docbook scripts use this to generate the footer: -->
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<productname>&COMMANDNAME;</productname>
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<productnumber>&VERSION;</productnumber>
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<firstname>Björn</firstname>
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<surname>Påhlsson</surname>
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<email>belorn@recompile.se</email>
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<email>belorn@fukt.bsnet.se</email>
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<firstname>Teddy</firstname>
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<surname>Hogeborn</surname>
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<email>teddy@recompile.se</email>
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<email>teddy@fukt.bsnet.se</email>
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<holder>Teddy Hogeborn</holder>
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<holder>Björn Påhlsson</holder>
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<xi:include href="legalnotice.xml"/>
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This manual page is free software: you can redistribute it
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and/or modify it under the terms of the GNU General Public
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License as published by the Free Software Foundation,
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either version 3 of the License, or (at your option) any
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This manual page is distributed in the hope that it will
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be useful, but WITHOUT ANY WARRANTY; without even the
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implied warranty of MERCHANTABILITY or FITNESS FOR A
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PARTICULAR PURPOSE. See the GNU General Public License
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You should have received a copy of the GNU General Public
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License along with this program; If not, see
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<ulink url="http://www.gnu.org/licenses/"/>.
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<refentrytitle>&COMMANDNAME;</refentrytitle>
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<manvolnum>8</manvolnum>
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<refname><command>&COMMANDNAME;</command></refname>
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Gives encrypted passwords to authenticated Mandos clients
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Sends encrypted passwords to authenticated Mandos clients
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<command>&COMMANDNAME;</command>
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<arg choice="plain"><option>--interface
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<replaceable>NAME</replaceable></option></arg>
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<arg choice="plain"><option>-i
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<replaceable>NAME</replaceable></option></arg>
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<arg choice="plain"><option>--address
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<replaceable>ADDRESS</replaceable></option></arg>
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<arg choice="plain"><option>-a
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<replaceable>ADDRESS</replaceable></option></arg>
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<arg choice="plain"><option>--port
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<replaceable>PORT</replaceable></option></arg>
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<arg choice="plain"><option>-p
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<replaceable>PORT</replaceable></option></arg>
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<arg><option>--priority
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<replaceable>PRIORITY</replaceable></option></arg>
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<arg><option>--servicename
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<replaceable>NAME</replaceable></option></arg>
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<arg><option>--configdir
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<replaceable>DIRECTORY</replaceable></option></arg>
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<arg><option>--debug</option></arg>
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<arg><option>--debuglevel
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<replaceable>LEVEL</replaceable></option></arg>
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<arg><option>--no-dbus</option></arg>
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<arg><option>--no-ipv6</option></arg>
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<arg><option>--no-restore</option></arg>
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<arg><option>--statedir
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<replaceable>DIRECTORY</replaceable></option></arg>
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<arg><option>--socket
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<replaceable>FD</replaceable></option></arg>
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<arg><option>--foreground</option></arg>
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<arg><option>--no-zeroconf</option></arg>
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<command>&COMMANDNAME;</command>
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<arg choice="plain"><option>--help</option></arg>
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<arg choice="plain"><option>-h</option></arg>
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<command>&COMMANDNAME;</command>
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<arg choice="plain"><option>--version</option></arg>
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<command>&COMMANDNAME;</command>
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<arg choice="plain"><option>--check</option></arg>
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<arg choice='opt'>--interface<arg choice='plain'>IF</arg></arg>
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<arg choice='opt'>--address<arg choice='plain'>ADDRESS</arg></arg>
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<arg choice='opt'>--port<arg choice='plain'>PORT</arg></arg>
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<arg choice='opt'>--priority<arg choice='plain'>PRIORITY</arg></arg>
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<arg choice='opt'>--servicename<arg choice='plain'>NAME</arg></arg>
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<arg choice='opt'>--configdir<arg choice='plain'>DIRECTORY</arg></arg>
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<arg choice='opt'>--debug</arg>
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<command>&COMMANDNAME;</command>
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<arg choice='opt'>-i<arg choice='plain'>IF</arg></arg>
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<arg choice='opt'>-a<arg choice='plain'>ADDRESS</arg></arg>
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<arg choice='opt'>-p<arg choice='plain'>PORT</arg></arg>
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<arg choice='opt'>--priority<arg choice='plain'>PRIORITY</arg></arg>
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<arg choice='opt'>--servicename<arg choice='plain'>NAME</arg></arg>
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<arg choice='opt'>--configdir<arg choice='plain'>DIRECTORY</arg></arg>
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<arg choice='opt'>--debug</arg>
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<command>&COMMANDNAME;</command>
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<arg choice='plain'>--help</arg>
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<command>&COMMANDNAME;</command>
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<arg choice='plain'>--version</arg>
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<command>&COMMANDNAME;</command>
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<arg choice='plain'>--check</arg>
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</refsynopsisdiv>
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<refsect1 id="description">
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<title>DESCRIPTION</title>
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<command>&COMMANDNAME;</command> is a server daemon which
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handles incoming requests for passwords for a pre-defined list
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of client host computers. For an introduction, see
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<citerefentry><refentrytitle>intro</refentrytitle>
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<manvolnum>8mandos</manvolnum></citerefentry>. The Mandos server
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uses Zeroconf to announce itself on the local network, and uses
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TLS to communicate securely with and to authenticate the
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clients. The Mandos server uses IPv6 to allow Mandos clients to
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use IPv6 link-local addresses, since the clients will probably
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not have any other addresses configured (see <xref
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linkend="overview"/>). Any authenticated client is then given
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the stored pre-encrypted password for that specific client.
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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 GnuTLS to
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communicate securely with and to authenticate the clients.
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Mandos uses IPv6 link-local addresses, since the clients are
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assumed to not have any other addresses configured. Any
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authenticated client is then given the pre-encrypted password
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for that specific client.
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<refsect1 id="purpose">
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<title>PURPOSE</title>
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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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rebooting</emphasis> of any client host computer with an
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<emphasis>encrypted root file system</emphasis>. The client
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host computer should start a Mandos client in the initial RAM
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disk environment, the Mandos client program communicates with
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this server program to get an encrypted password, which is then
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decrypted and used to unlock the encrypted root file system.
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The client host computer can then continue its boot sequence
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<refsect1 id="options">
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<title>OPTIONS</title>
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<term><option>--help</option></term>
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<term><option>-h</option></term>
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<term><literal>-h</literal>, <literal>--help</literal></term>
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Show a help message and exit
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<term><option>--interface</option>
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<replaceable>NAME</replaceable></term>
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<term><option>-i</option>
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<replaceable>NAME</replaceable></term>
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<xi:include href="mandos-options.xml" xpointer="interface"/>
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<term><option>--address
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<replaceable>ADDRESS</replaceable></option></term>
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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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<replaceable>PORT</replaceable></option></term>
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<replaceable>PORT</replaceable></option></term>
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<xi:include href="mandos-options.xml" xpointer="port"/>
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<term><option>--check</option></term>
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Run the server’s self-tests. This includes any unit
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<term><literal>-i</literal>, <literal>--interface <replaceable>
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IF</replaceable></literal></term>
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Only announce the server and listen to requests on network
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interface <replaceable>IF</replaceable>. Default is to
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use all available interfaces.
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<term><literal>-a</literal>, <literal>--address <replaceable>
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ADDRESS</replaceable></literal></term>
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If this option is used, the server will only listen to a
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specific address. This must currently be an IPv6 address;
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an IPv4 address can be specified using the
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<quote><literal>::FFFF:192.0.2.3</literal></quote> syntax.
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Also, if a link-local address is specified, an interface
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should be set, since a link-local address is only valid on
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a single interface. By default, the server will listen to
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all available addresses.
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<term><literal>-p</literal>, <literal>--port <replaceable>
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PORT</replaceable></literal></term>
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If this option is used, the server to bind to that
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port. By default, the server will listen to an arbitrary
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port given by the operating system.
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<term><literal>--check</literal></term>
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Run the server's self-tests. This includes any unit
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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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<term><option>--debuglevel
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<replaceable>LEVEL</replaceable></option></term>
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Set the debugging log level.
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<replaceable>LEVEL</replaceable> is a string, one of
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<quote><literal>CRITICAL</literal></quote>,
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<quote><literal>ERROR</literal></quote>,
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<quote><literal>WARNING</literal></quote>,
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<quote><literal>INFO</literal></quote>, or
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<quote><literal>DEBUG</literal></quote>, in order of
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increasing verbosity. The default level is
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<quote><literal>WARNING</literal></quote>.
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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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<term><option>--servicename
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<replaceable>NAME</replaceable></option></term>
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<xi:include href="mandos-options.xml"
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xpointer="servicename"/>
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<term><option>--configdir
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<replaceable>DIRECTORY</replaceable></option></term>
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<term><literal>--debug</literal></term>
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If the server is run in debug mode, it will run in the
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foreground and print a lot of debugging information. The
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default is <emphasis>not</emphasis> to run in debug mode.
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<term><literal>--priority <replaceable>
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PRIORITY</replaceable></literal></term>
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GnuTLS priority string for the TLS handshake with the
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<citerefentry><refentrytitle>gnutls_priority_init
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</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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for the syntax. The default is
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<quote><literal>SECURE256:!CTYPE-X.509:+CTYPE-OPENPGP</literal></quote>.
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<emphasis>Warning</emphasis>: changing this may make the
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TLS handshake fail, making communication with clients
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<term><literal>--servicename <replaceable>NAME</replaceable>
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Zeroconf service name. The default is
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<quote><literal>Mandos</literal></quote>. You only need
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to change this if you for some reason want to run more
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than one server on the same <emphasis>host</emphasis>,
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which would not normally be useful. If there are name
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collisions on the same <emphasis>network</emphasis>, the
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newer server will automatically rename itself to
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<quote><literal>Mandos #2</literal></quote>, and so on,
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therefore this option is not needed in that case.
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<term><literal>--configdir <replaceable>DIR</replaceable>
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Directory to search for configuration files. Default is
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</tbody></tgroup></table>
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<refsect1 id="checking">
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<title>CHECKING</title>
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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. (Manual
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intervention is required to re-enable a client.) The timeout,
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extended timeout, checker program, and interval between checks
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can be configured both globally and per client; see
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<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
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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.conf</refentrytitle>
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<manvolnum>5</manvolnum></citerefentry> and <citerefentry>
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<refentrytitle>mandos-clients.conf</refentrytitle>
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<manvolnum>5</manvolnum></citerefentry>.
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<refsect1 id="approval">
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<title>APPROVAL</title>
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The server can be configured to require manual approval for a
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client before it is sent its secret. The delay to wait for such
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approval and the default action (approve or deny) can be
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configured both globally and per client; see <citerefentry>
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<refentrytitle>mandos-clients.conf</refentrytitle>
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<manvolnum>5</manvolnum></citerefentry>. By default all clients
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will be approved immediately without delay.
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This can be used to deny a client its secret if not manually
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approved within a specified time. It can also be used to make
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the server delay before giving a client its secret, allowing
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optional manual denying of this specific client.
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<refsect1 id="logging">
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<title>LOGGING</title>
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The server will send log message with various severity levels to
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<filename class="devicefile">/dev/log</filename>. With the
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The server will send log messaged with various severity levels
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to <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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<refsect1 id="persistent_state">
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<title>PERSISTENT STATE</title>
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Client settings, initially read from
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<filename>clients.conf</filename>, are persistent across
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restarts, and run-time changes will override settings in
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<filename>clients.conf</filename>. However, if a setting is
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<emphasis>changed</emphasis> (or a client added, or removed) in
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<filename>clients.conf</filename>, this will take precedence.
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<refsect1 id="dbus_interface">
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<title>D-BUS INTERFACE</title>
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The server will by default provide a D-Bus system bus interface.
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This interface will only be accessible by the root user or a
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Mandos-specific user, if such a user exists. For documentation
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of the D-Bus API, see the file <filename>DBUS-API</filename>.
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<refsect1 id="exit_status">
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<title>EXIT STATUS</title>
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<!-- do not wrap this line -->
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<userinput>&COMMANDNAME; --interface eth7 --address fe80::aede:48ff:fe71:f6f2</userinput>
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<userinput>mandos --interface eth7 --address fe80::aede:48ff:fe71:f6f2</userinput>
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</informalexample>
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<refsect1 id="security">
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<title>SECURITY</title>
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<refsect2 id="server">
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<title>SERVER</title>
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Running this <command>&COMMANDNAME;</command> server program
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should not in itself present any security risk to the host
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computer running it. The program switches to a non-root user
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Running the server should not in itself present any security
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risk to the host computer running it.
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<refsect2 id="clients">
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<title>CLIENTS</title>
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The server only gives out its stored data to clients which
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does have the correct key ID of the stored key ID. This is
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guaranteed by the fact that the client sends its public key in
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the TLS handshake; this ensures it to be genuine. The server
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computes the key ID of the key itself and looks up the key ID
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in its list of clients. The <filename>clients.conf</filename>
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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
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public key in the TLS handshake; this ensures it to be
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genuine. The server computes the fingerprint of the key
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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>
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<manvolnum>5</manvolnum></citerefentry>)
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<emphasis>must</emphasis> be made non-readable by anyone
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except the user starting the server (usually root).
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As detailed in <xref linkend="checking"/>, the status of all
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client computers will continually be checked and be assumed
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compromised if they are gone for too long.
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<manvolnum>5</manvolnum></citerefentry>) must be non-readable
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by anyone except the user running the server.
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For more details on client-side security, see
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<citerefentry><refentrytitle>mandos-client</refentrytitle>
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<citerefentry><refentrytitle>password-request</refentrytitle>
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<manvolnum>8mandos</manvolnum></citerefentry>.
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<refsect1 id="see_also">
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<title>SEE ALSO</title>
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<citerefentry><refentrytitle>intro</refentrytitle>
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<manvolnum>8mandos</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
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<manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>mandos.conf</refentrytitle>
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<manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>mandos-client</refentrytitle>
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<manvolnum>8mandos</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sh</refentrytitle>
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<manvolnum>1</manvolnum></citerefentry>
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<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
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Zeroconf is the network protocol standard used by clients
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for finding this Mandos server on the local network.
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<ulink url="https://www.avahi.org/">Avahi</ulink>
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Avahi is the library this server calls to implement
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Zeroconf service announcements.
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<ulink url="https://gnutls.org/">GnuTLS</ulink>
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GnuTLS is the library this server uses to implement TLS for
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communicating securely with the client, and at the same time
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confidently get the client’s public key.
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RFC 4291: <citetitle>IP Version 6 Addressing
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Architecture</citetitle>
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<term>Section 2.2: <citetitle>Text Representation of
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Addresses</citetitle></term>
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<listitem><para/></listitem>
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<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
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Address</citetitle></term>
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<listitem><para/></listitem>
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<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
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Addresses</citetitle></term>
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The clients use IPv6 link-local addresses, which are
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immediately usable since a link-local address is
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automatically assigned to a network interfaces when it
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RFC 5246: <citetitle>The Transport Layer Security (TLS)
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Protocol Version 1.2</citetitle>
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TLS 1.2 is the protocol implemented by GnuTLS.
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RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
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The data sent to clients is binary encrypted OpenPGP data.
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RFC 7250: <citetitle>Using Raw Public Keys in Transport
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Layer Security (TLS) and Datagram Transport Layer Security
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This is implemented by GnuTLS version 3.6.6 and is, if
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present, used by this server so that raw public keys can be
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RFC 6091: <citetitle>Using OpenPGP Keys for Transport Layer
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Security (TLS) Authentication</citetitle>
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This is implemented by GnuTLS before version 3.6.0 and is,
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if present, used by this server so that OpenPGP keys can be
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<itemizedlist spacing="compact">
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<citerefentry><refentrytitle>password-request</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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<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
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<ulink url="http://www.avahi.org/">Avahi</ulink>
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url="http://www.gnu.org/software/gnutls/">GnuTLS</ulink>
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<citation>RFC 4880: <citetitle>OpenPGP Message
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Format</citetitle></citation>
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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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<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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