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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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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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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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<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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<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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<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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"<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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<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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new server will automatically rename itself to "Mandos
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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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"<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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<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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<title>NETWORK PROTOCOL</title>
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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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<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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<informaltable><tgroup cols="3"><thead>
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<title>Mandos Protocol (Version 1)</title><tgroup cols="3"><thead>
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<entry>Mandos Client</entry>
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<entry>Direction</entry>
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<entry>-><!-- → --></entry>
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<entry>"<literal>1\r\en</literal>"</entry>
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<entry><quote><literal>1\r\en</literal></quote></entry>
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<entry>-><!-- → --></entry>
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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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<entry><-><!-- ⟷ --></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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<entry>OpenPGP public key (part of TLS handshake)</entry>
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<entry><-<!-- ← --></entry>
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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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<entry><-<!-- ← --></entry>
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<entry>Close</entry>
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</tbody></tgroup></informaltable>
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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
341
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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<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="logging">
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<title>LOGGING</title>
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The server will log a lot of information with various severity
336
<citerefentry><refentrytitle>syslog</refentrytitle>
337
<manvolnum>8</manvolnum></citerefentry>. With the
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The server will send log messaged with various severity levels
357
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="file">
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<title>FILES</title>
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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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<filename>/etc/mandos/clients.conf</filename> See <citerefentry>
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<refentrytitle>mandos-clients.conf</refentrytitle>
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<manvolnum>5</manvolnum></citerefentry>.
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<filename>/var/run/mandos/mandos.pid</filename>
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Use the <option>--configdir</option> option to change where
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<command>&COMMANDNAME;</command> looks for its configurations
376
files. The default file names are listed here.
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<term><filename>/etc/mandos/mandos.conf</filename></term>
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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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<term><filename>/etc/mandos/clients.conf</filename></term>
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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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<term><filename>/var/run/mandos/mandos.pid</filename></term>
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The file containing the process id of
404
<command>&COMMANDNAME;</command>.
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<term><filename>/dev/log</filename></term>
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The Unix domain socket to where local syslog messages are
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420
<refsect1 id="bugs">
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<title>BUGS</title>
423
This server might, on especially fatal errors, emit a Python
424
backtrace. This could be considered a feature.
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<refsect1 id="examples">
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<title>EXAMPLES</title>
432
Normal invocation needs no options:
435
<userinput>mandos</userinput>
440
Run the server in debug mode and read configuration files from
441
the <filename>~/mandos</filename> directory:
445
<!-- do not wrap this line -->
446
<userinput>mandos --debug --configdir ~/mandos --servicename Test</userinput>
452
Run the server normally, but only listen to one interface and
453
only on the link-local address on that interface:
457
<!-- do not wrap this line -->
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<userinput>mandos --interface eth7 --address fe80::aede:48ff:fe71:f6f2</userinput>
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<refsect1 id="security">
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<title>SECURITY</title>
467
<title>SERVER</title>
469
Running the server should not in itself present any security
470
risk to the host computer running it.
474
<title>CLIENTS</title>
476
The server only gives out its stored data to clients which
477
does have the OpenPGP key of the stored fingerprint. This is
478
guaranteed by the fact that the client sends its OpenPGP
479
public key in the TLS handshake; this ensures it to be
480
genuine. The server computes the fingerprint of the key
481
itself and looks up the fingerprint in its list of
482
clients. The <filename>clients.conf</filename> file (see
483
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
484
<manvolnum>5</manvolnum></citerefentry>) must be non-readable
485
by anyone except the user running the server.
488
For more details on client-side security, see
489
<citerefentry><refentrytitle>password-request</refentrytitle>
490
<manvolnum>8mandos</manvolnum></citerefentry>.
390
495
<refsect1 id="see_also">