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Committer: Teddy Hogeborn
Date: 2008-08-18 03:50:28 UTC
Revision ID: teddy@fukt.bsnet.se-20080818035028-su31apqs2pv2147v

* mandos-keygen.xml: Removed <?xml-stylesheet>.  New entity
                     "&OVERVIEW;" referring to "overview.xml".
  (PURPOSE, OVERVIEW): New sections, same as in mandos(8).
  (EXAMPLES): Renamed to "EXAMPLE", as per man-pages(7).

* mandos.xml (OPTIONS, CLIENTS): Slight wording change.

files added:
overview.xml

files modified:
Makefile

TODO

mandos-keygen.xml

mandos.xml

plugins.d/password-request.c

Show diffs side-by-side

added added

removed removed

mandos.xml

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

<?xml-stylesheet type="text/xsl"

href="http://docbook.sourceforge.net/release/xsl/current/manpages/docbook.xsl"?>

<?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 OVERVIEW SYSTEM "overview.xml">

<title>&COMMANDNAME;</title>

<productname>&COMMANDNAME;</productname>

<productnumber>&VERSION;</productnumber>

<command>&COMMANDNAME;</command>

<arg choice='opt'>--interface<arg choice='plain'>IF</arg></arg>

<arg choice='opt'>--address<arg choice='plain'>ADDRESS</arg></arg>

<arg choice='opt'>--priority<arg choice='plain'>PRIORITY</arg></arg>

<arg choice='opt'>--servicename<arg choice='plain'>NAME</arg></arg>

<arg choice='opt'>--configdir<arg choice='plain'>DIRECTORY</arg></arg>

<arg choice='opt'>--debug</arg>

</cmdsynopsis>

<command>&COMMANDNAME;</command>

<arg choice='opt'>-a<arg choice='plain'>ADDRESS</arg></arg>

<arg choice='opt'>--priority<arg choice='plain'>PRIORITY</arg></arg>

<arg choice='opt'>--servicename<arg choice='plain'>NAME</arg></arg>

<arg choice='opt'>--configdir<arg choice='plain'>DIRECTORY</arg></arg>

<arg choice='opt'>--debug</arg>

</cmdsynopsis>

<command>&COMMANDNAME;</command>

</cmdsynopsis>

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<command>&COMMANDNAME;</command>

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<arg choice='plain'>--version</arg>

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</cmdsynopsis>

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<command>&COMMANDNAME;</command>

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<arg choice='plain'>--check</arg>

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</cmdsynopsis>

<arg>--interface<arg choice="plain">IF</arg></arg>

<arg>--address<arg choice="plain">ADDRESS</arg></arg>

<arg>--priority<arg choice="plain">PRIORITY</arg></arg>

<arg>--servicename<arg choice="plain">NAME</arg></arg>

<arg>--configdir<arg choice="plain">DIRECTORY</arg></arg>

<arg>--debug</arg>

</cmdsynopsis>

<command>&COMMANDNAME;</command>

<arg>-a<arg choice="plain">ADDRESS</arg></arg>

<arg>--priority<arg choice="plain">PRIORITY</arg></arg>

<arg>--servicename<arg choice="plain">NAME</arg></arg>

<arg>--configdir<arg choice="plain">DIRECTORY</arg></arg>

<arg>--debug</arg>

</cmdsynopsis>

<command>&COMMANDNAME;</command>

</group>

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</cmdsynopsis>

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<command>&COMMANDNAME;</command>

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

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</cmdsynopsis>

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<command>&COMMANDNAME;</command>

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

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</cmdsynopsis>

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</refsynopsisdiv>

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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 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 yet. 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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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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</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 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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normally.

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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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</refsect1>

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<title>OPTIONS</title>

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<para>

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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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use all available interfaces. <emphasis>Note:</emphasis>

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a failure to bind to the specified interface is not

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considered critical, and the server does not exit.

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</para>

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</listitem>

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</varlistentry>

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</varlistentry>

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<term><literal>-a</literal>, <literal>--address <replaceable>

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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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"<literal>::FFFF:192.0.2.3</literal>" syntax. Also, if a

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link-local address is specified, an interface should be

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set, since a link-local address is only valid on a single

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interface. By default, the server will listen to all

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available addresses.

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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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</para>

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</listitem>

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</varlistentry>

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</varlistentry>

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port given by the operating system.

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</para>

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</listitem>

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</varlistentry>

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</varlistentry>

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<term><literal>--check</literal></term>

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<para>

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

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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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</varlistentry>

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<term><literal>--debug</literal></term>

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<para>

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GnuTLS priority string for the TLS handshake with the

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clients. See

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<citerefentry><refentrytitle>gnutls_priority_init

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clients. The default is

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<quote><literal>SECURE256:!CTYPE-X.509:+CTYPE-OPENPGP</literal></quote>.

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See <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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"<literal>SECURE256:!CTYPE-X.509:+CTYPE-OPENPGP</literal>".

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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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impossible.

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for the syntax. <emphasis>Warning</emphasis>: changing

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this may make the TLS handshake fail, making communication

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with clients impossible.

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</para>

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</listitem>

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</varlistentry>

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</varlistentry>

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<term><literal>--servicename <replaceable>NAME</replaceable>

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<para>

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Zeroconf service name. The default is

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"<literal>Mandos</literal>". You only need to change this

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if you for some reason want to run more than one server on

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the same <emphasis>host</emphasis>. If there are name

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collisions on the same <emphasis>network</emphasis>, the

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new server will automatically rename itself to "Mandos

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#2", etc.

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<quote><literal>Mandos</literal></quote>. This only needs

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to be changed this if it, for some reason, is necessary to

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run more than one server on the same

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<emphasis>host</emphasis>, which would not normally be

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useful. If there are name collisions on the same

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<emphasis>network</emphasis>, the newer server will

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automatically rename itself to <quote><literal>Mandos

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#2</literal></quote>, and so on; therefore, this option is

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not needed in that case.

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</para>

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</listitem>

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</varlistentry>

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</varlistentry>

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<term><literal>--configdir <replaceable>DIR</replaceable>

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<para>

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Directory to search for configuration files. Default is

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"<literal>/etc/mandos</literal>". See <citerefentry>

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<refentrytitle>mandos.conf</refentrytitle>

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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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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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</varlistentry>

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</variablelist>

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</refsect1>

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<title>OVERVIEW</title>

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&OVERVIEW;

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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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RAM 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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"<literal>_mandos._tcp</literal>". The Mandos client connects

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to the announced address and port, and sends a line of text

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where the first whitespace-separated field is the protocol

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version, which currently is "<literal>1</literal>". The client

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and server then start a TLS protocol handshake with a slight

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quirk: the Mandos server program acts as a TLS "client" while

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the connecting Mandos client acts as a TLS "server". The Mandos

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client must supply an OpenPGP certificate, and the fingerprint

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of this certificate is used by the Mandos server to look up (in

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a list read from a file at start time) which binary blob to give

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the client. No other authentication or authorization is done by

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the server.

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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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</row>

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<row>

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</row>

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<row>

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<entry>TLS handshake</entry>

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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</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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<entry>Binary blob</entry>

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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></informaltable>

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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.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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</refsect1>

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<title>LOGGING</title>

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<para>

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The server will log a lot of information with various severity

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levels to

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<citerefentry><refentrytitle>syslog</refentrytitle>

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<manvolnum>8</manvolnum></citerefentry>. 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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</para>

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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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<filename>/etc/mandos/mandos.conf</filename> See <citerefentry>

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<refentrytitle>mandos.conf</refentrytitle>

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

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</para></listitem>

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<filename>/etc/mandos/clients.conf</filename> See <citerefentry>

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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>.

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</para></listitem>

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

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</para></listitem>

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</itemizedlist>

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</para>

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</refsect1>

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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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</para>

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</refsect1>

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<title>EXAMPLES</title>

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<para>

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</para>

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

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backtrace. This could be considered a feature.

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</para>

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<para>

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

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

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permanent storage. This has some security implications, see

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<xref linkend="CLIENTS"/>.

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</para>

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<para>

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

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status of clients, other than analyzing its <systemitem

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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.

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</para>

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<para>

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The console log messages does not show a timestamp.

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</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:

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</para>

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<para>

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<userinput>mandos</userinput>

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</para>

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</informalexample>

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<para>

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Run the server in debug mode, read configuration files from

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

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

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any other official Mandos server on this host:

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</para>

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<para>

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<userinput>mandos --debug --configdir ~/mandos --servicename Test</userinput>

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</para>

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</informalexample>

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<para>

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

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only on the link-local address on that interface:

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</para>

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<para>

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<userinput>mandos --interface eth7 --address fe80::aede:48ff:fe71:f6f2</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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</para>

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<title>SERVER</title>

531

<para>

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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 does not need any special

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

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</para>

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</refsect2>

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<title>CLIENTS</title>

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<para>

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The server only gives out its stored data to clients which

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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>

549

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

550

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

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except the user running the server.

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</para>

553

<para>

554

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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</para>

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<para>

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

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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 RAM image of the client host. What should be done in

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that case (if restarting the server program really is

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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>

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For more details on client-side security, see

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

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

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</para>

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</refsect2>

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</refsect1>

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

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

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</para></listitem>

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

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

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</para></listitem>

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

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</para></listitem>

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

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</para></listitem>

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<ulink

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

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</para></listitem>

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<citation>RFC 4880: <citetitle>OpenPGP Message

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Format</citetitle></citation>

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</para></listitem>

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

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Transport Layer Security</citetitle></citation>

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</para></listitem>

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

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

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Unicast Addresses</citation>

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</para></listitem>

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</itemizedlist>

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<term>

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<refentrytitle>password-request</refentrytitle>

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<manvolnum>8mandos</manvolnum>

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</citerefentry>

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</term>

592

593

<para>

594

This is the actual program which talks to this server.

595

Note that it is normally not invoked directly, and is only

596

run in the initial RAM disk environment, and not on a

597

fully started system.

598

</para>

599

</listitem>

600

</varlistentry>

601

602

<term>

603

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

604

</term>

605

606

<para>

607

Zeroconf is the network protocol standard used by clients

608

for finding this Mandos server on the local network.

609

</para>

610

</listitem>

611

</varlistentry>

612

613

<term>

614

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

615

</term>

616

617

<para>

618

Avahi is the library this server calls to implement

619

Zeroconf service announcements.

620

</para>

621

</listitem>

622

</varlistentry>

623

624

<term>

625

<ulink

626

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

627

</term>

628

629

<para>

630

GnuTLS is the library this server uses to implement TLS for

631

communicating securely with the client, and at the same time

632

confidently get the client’s public OpenPGP key.

633

</para>

634

</listitem>

635

</varlistentry>

636

637

<term>

638

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

639

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

640

Unicast Addresses</citation>

641

</term>

642

643

<para>

644

The clients use IPv6 link-local addresses, which are

645

immediately usable since a link-local addresses is

646

automatically assigned to a network interfaces when it is

647

brought up.

648

</para>

649

</listitem>

650

</varlistentry>

651

652

<term>

653

<citation>RFC 4346: <citetitle>The Transport Layer Security

654

(TLS) Protocol Version 1.1</citetitle></citation>

655

</term>

656

657

<para>

658

TLS 1.1 is the protocol implemented by GnuTLS.

659

</para>

660

</listitem>

661

</varlistentry>

662

663

<term>

664

<citation>RFC 4880: <citetitle>OpenPGP Message

665

Format</citetitle></citation>

666

</term>

667

668

<para>

669

The data sent to clients is binary encrypted OpenPGP data.

670

</para>

671

</listitem>

672

</varlistentry>

673

674

<term>

675

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

676

Transport Layer Security</citetitle></citation>

677

</term>

678

679

<para>

680

This is implemented by GnuTLS and used by this server so

681

that OpenPGP keys can be used.

682

</para>

683

</listitem>

684

</varlistentry>

685

</variablelist>

432

686

</refsect1>

433

687

</refentry>

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