67
48
<refname><command>&COMMANDNAME;</command></refname>
69
Sends encrypted passwords to authenticated mandos clients
50
Gives encrypted passwords to authenticated Mandos clients
75
56
<command>&COMMANDNAME;</command>
76
<arg choice='opt' rep='repeat'>OPTION</arg>
58
<arg choice="plain"><option>--interface
59
<replaceable>NAME</replaceable></option></arg>
60
<arg choice="plain"><option>-i
61
<replaceable>NAME</replaceable></option></arg>
65
<arg choice="plain"><option>--address
66
<replaceable>ADDRESS</replaceable></option></arg>
67
<arg choice="plain"><option>-a
68
<replaceable>ADDRESS</replaceable></option></arg>
72
<arg choice="plain"><option>--port
73
<replaceable>PORT</replaceable></option></arg>
74
<arg choice="plain"><option>-p
75
<replaceable>PORT</replaceable></option></arg>
78
<arg><option>--priority
79
<replaceable>PRIORITY</replaceable></option></arg>
81
<arg><option>--servicename
82
<replaceable>NAME</replaceable></option></arg>
84
<arg><option>--configdir
85
<replaceable>DIRECTORY</replaceable></option></arg>
87
<arg><option>--debug</option></arg>
89
<arg><option>--no-dbus</option></arg>
92
<command>&COMMANDNAME;</command>
94
<arg choice="plain"><option>--help</option></arg>
95
<arg choice="plain"><option>-h</option></arg>
99
<command>&COMMANDNAME;</command>
100
<arg choice="plain"><option>--version</option></arg>
103
<command>&COMMANDNAME;</command>
104
<arg choice="plain"><option>--check</option></arg>
80
108
<refsect1 id="description">
81
109
<title>DESCRIPTION</title>
83
<command>&COMMANDNAME;</command> is a server daemon that handels
84
incomming passwords request for passwords. Mandos use avahi to
85
announce the service, and through gnutls authenticates
86
clients. Any authenticated client is then given its encrypted
92
<term><literal>-h</literal>, <literal>--help</literal></term>
95
show a help message and exit
101
<term><literal>-i</literal>, <literal>--interface <replaceable>
102
IF</replaceable></literal></term>
111
<term><literal>-a</literal>, <literal>--address <replaceable>
112
ADDRESS</replaceable></literal></term>
115
Address to listen for requests on
121
<term><literal>-p</literal>, <literal>--port <replaceable>
122
PORT</replaceable></literal></term>
125
Port number to receive requests on
131
<term><literal>--check</literal></term>
134
Run self-test on the server
140
<term><literal>--debug</literal></term>
149
<term><literal>--priority <replaceable>
150
PRIORITY</replaceable></literal></term>
153
GnuTLS priority string. See <citerefentry>
154
<refentrytitle>gnutls_priority_init</refentrytitle>
155
<manvolnum>3</manvolnum></citerefentry>
161
<term><literal>--servicename <replaceable>NAME</replaceable>
165
Zeroconf service name
171
<term><literal>--configdir <replaceable>DIR</replaceable>
175
Directory to search for configuration files
111
<command>&COMMANDNAME;</command> is a server daemon which
112
handles incoming request for passwords for a pre-defined list of
113
client host computers. The Mandos server uses Zeroconf to
114
announce itself on the local network, and uses TLS to
115
communicate securely with and to authenticate the clients. The
116
Mandos server uses IPv6 to allow Mandos clients to use IPv6
117
link-local addresses, since the clients will probably not have
118
any other addresses configured (see <xref linkend="overview"/>).
119
Any authenticated client is then given the stored pre-encrypted
120
password for that specific client.
124
<refsect1 id="purpose">
125
<title>PURPOSE</title>
127
The purpose of this is to enable <emphasis>remote and unattended
128
rebooting</emphasis> of client host computer with an
129
<emphasis>encrypted root file system</emphasis>. See <xref
130
linkend="overview"/> for details.
134
<refsect1 id="options">
135
<title>OPTIONS</title>
138
<term><option>--help</option></term>
139
<term><option>-h</option></term>
142
Show a help message and exit
148
<term><option>--interface</option>
149
<replaceable>NAME</replaceable></term>
150
<term><option>-i</option>
151
<replaceable>NAME</replaceable></term>
153
<xi:include href="mandos-options.xml" xpointer="interface"/>
158
<term><option>--address
159
<replaceable>ADDRESS</replaceable></option></term>
161
<replaceable>ADDRESS</replaceable></option></term>
163
<xi:include href="mandos-options.xml" xpointer="address"/>
169
<replaceable>PORT</replaceable></option></term>
171
<replaceable>PORT</replaceable></option></term>
173
<xi:include href="mandos-options.xml" xpointer="port"/>
178
<term><option>--check</option></term>
181
Run the server’s self-tests. This includes any unit
188
<term><option>--debug</option></term>
190
<xi:include href="mandos-options.xml" xpointer="debug"/>
195
<term><option>--priority <replaceable>
196
PRIORITY</replaceable></option></term>
198
<xi:include href="mandos-options.xml" xpointer="priority"/>
203
<term><option>--servicename
204
<replaceable>NAME</replaceable></option></term>
206
<xi:include href="mandos-options.xml"
207
xpointer="servicename"/>
212
<term><option>--configdir
213
<replaceable>DIRECTORY</replaceable></option></term>
216
Directory to search for configuration files. Default is
217
<quote><literal>/etc/mandos</literal></quote>. See
218
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
219
<manvolnum>5</manvolnum></citerefentry> and <citerefentry>
220
<refentrytitle>mandos-clients.conf</refentrytitle>
221
<manvolnum>5</manvolnum></citerefentry>.
227
<term><option>--version</option></term>
230
Prints the program version and exit.
236
<term><option>--no-dbus</option></term>
238
<xi:include href="mandos-options.xml" xpointer="dbus"/>
240
See also <xref linkend="dbus_interface"/>.
247
<refsect1 id="overview">
248
<title>OVERVIEW</title>
249
<xi:include href="overview.xml"/>
251
This program is the server part. It is a normal server program
252
and will run in a normal system environment, not in an initial
253
<acronym>RAM</acronym> disk environment.
257
<refsect1 id="protocol">
258
<title>NETWORK PROTOCOL</title>
260
The Mandos server announces itself as a Zeroconf service of type
261
<quote><literal>_mandos._tcp</literal></quote>. The Mandos
262
client connects to the announced address and port, and sends a
263
line of text where the first whitespace-separated field is the
264
protocol version, which currently is
265
<quote><literal>1</literal></quote>. The client and server then
266
start a TLS protocol handshake with a slight quirk: the Mandos
267
server program acts as a TLS <quote>client</quote> while the
268
connecting Mandos client acts as a TLS <quote>server</quote>.
269
The Mandos client must supply an OpenPGP certificate, and the
270
fingerprint of this certificate is used by the Mandos server to
271
look up (in a list read from <filename>clients.conf</filename>
272
at start time) which binary blob to give the client. No other
273
authentication or authorization is done by the server.
276
<title>Mandos Protocol (Version 1)</title><tgroup cols="3"><thead>
278
<entry>Mandos Client</entry>
279
<entry>Direction</entry>
280
<entry>Mandos Server</entry>
284
<entry>Connect</entry>
285
<entry>-><!-- → --></entry>
288
<entry><quote><literal>1\r\n</literal></quote></entry>
289
<entry>-><!-- → --></entry>
292
<entry>TLS handshake <emphasis>as TLS <quote>server</quote>
294
<entry><-><!-- ⟷ --></entry>
295
<entry>TLS handshake <emphasis>as TLS <quote>client</quote>
299
<entry>OpenPGP public key (part of TLS handshake)</entry>
300
<entry>-><!-- → --></entry>
304
<entry><-<!-- ← --></entry>
305
<entry>Binary blob (client will assume OpenPGP data)</entry>
309
<entry><-<!-- ← --></entry>
312
</tbody></tgroup></table>
315
<refsect1 id="checking">
316
<title>CHECKING</title>
318
The server will, by default, continually check that the clients
319
are still up. If a client has not been confirmed as being up
320
for some time, the client is assumed to be compromised and is no
321
longer eligible to receive the encrypted password. The timeout,
322
checker program, and interval between checks can be configured
323
both globally and per client; see <citerefentry>
324
<refentrytitle>mandos-clients.conf</refentrytitle>
325
<manvolnum>5</manvolnum></citerefentry>.
329
<refsect1 id="logging">
330
<title>LOGGING</title>
332
The server will send log message with various severity levels to
333
<filename>/dev/log</filename>. With the
334
<option>--debug</option> option, it will log even more messages,
335
and also show them on the console.
339
<refsect1 id="dbus_interface">
340
<title>D-BUS INTERFACE</title>
342
The server will by default provide a D-Bus system bus interface.
343
This interface will only be accessible by the root user or a
344
Mandos-specific user, if such a user exists.
349
<refsect1 id="exit_status">
350
<title>EXIT STATUS</title>
352
The server will exit with a non-zero exit status only when a
353
critical error is encountered.
357
<refsect1 id="environment">
358
<title>ENVIRONMENT</title>
361
<term><envar>PATH</envar></term>
364
To start the configured checker (see <xref
365
linkend="checking"/>), the server uses
366
<filename>/bin/sh</filename>, which in turn uses
367
<varname>PATH</varname> to search for matching commands if
368
an absolute path is not given. See <citerefentry>
369
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
377
<refsect1 id="files">
380
Use the <option>--configdir</option> option to change where
381
<command>&COMMANDNAME;</command> looks for its configurations
382
files. The default file names are listed here.
386
<term><filename>/etc/mandos/mandos.conf</filename></term>
389
Server-global settings. See
390
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
391
<manvolnum>5</manvolnum></citerefentry> for details.
396
<term><filename>/etc/mandos/clients.conf</filename></term>
399
List of clients and client-specific settings. See
400
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
401
<manvolnum>5</manvolnum></citerefentry> for details.
406
<term><filename>/var/run/mandos.pid</filename></term>
409
The file containing the process id of
410
<command>&COMMANDNAME;</command>.
415
<term><filename>/dev/log</filename></term>
418
The Unix domain socket to where local syslog messages are
424
<term><filename>/bin/sh</filename></term>
427
This is used to start the configured checker command for
428
each client. See <citerefentry>
429
<refentrytitle>mandos-clients.conf</refentrytitle>
430
<manvolnum>5</manvolnum></citerefentry> for details.
440
This server might, on especially fatal errors, emit a Python
441
backtrace. This could be considered a feature.
444
Currently, if a client is declared <quote>invalid</quote> due to
445
having timed out, the server does not record this fact onto
446
permanent storage. This has some security implications, see
447
<xref linkend="clients"/>.
450
There is currently no way of querying the server of the current
451
status of clients, other than analyzing its <systemitem
452
class="service">syslog</systemitem> output.
455
There is no fine-grained control over logging and debug output.
458
Debug mode is conflated with running in the foreground.
461
The console log messages does not show a time stamp.
464
This server does not check the expire time of clients’ OpenPGP
469
<refsect1 id="example">
470
<title>EXAMPLE</title>
473
Normal invocation needs no options:
476
<userinput>&COMMANDNAME;</userinput>
481
Run the server in debug mode, read configuration files from
482
the <filename>~/mandos</filename> directory, and use the
483
Zeroconf service name <quote>Test</quote> to not collide with
484
any other official Mandos server on this host:
488
<!-- do not wrap this line -->
489
<userinput>&COMMANDNAME; --debug --configdir ~/mandos --servicename Test</userinput>
495
Run the server normally, but only listen to one interface and
496
only on the link-local address on that interface:
500
<!-- do not wrap this line -->
501
<userinput>&COMMANDNAME; --interface eth7 --address fe80::aede:48ff:fe71:f6f2</userinput>
507
<refsect1 id="security">
508
<title>SECURITY</title>
509
<refsect2 id="server">
510
<title>SERVER</title>
512
Running this <command>&COMMANDNAME;</command> server program
513
should not in itself present any security risk to the host
514
computer running it. The program switches to a non-root user
518
<refsect2 id="clients">
519
<title>CLIENTS</title>
521
The server only gives out its stored data to clients which
522
does have the OpenPGP key of the stored fingerprint. This is
523
guaranteed by the fact that the client sends its OpenPGP
524
public key in the TLS handshake; this ensures it to be
525
genuine. The server computes the fingerprint of the key
526
itself and looks up the fingerprint in its list of
527
clients. The <filename>clients.conf</filename> file (see
528
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
529
<manvolnum>5</manvolnum></citerefentry>)
530
<emphasis>must</emphasis> be made non-readable by anyone
531
except the user starting the server (usually root).
534
As detailed in <xref linkend="checking"/>, the status of all
535
client computers will continually be checked and be assumed
536
compromised if they are gone for too long.
539
If a client is compromised, its downtime should be duly noted
540
by the server which would therefore declare the client
541
invalid. But if the server was ever restarted, it would
542
re-read its client list from its configuration file and again
543
regard all clients therein as valid, and hence eligible to
544
receive their passwords. Therefore, be careful when
545
restarting servers if it is suspected that a client has, in
546
fact, been compromised by parties who may now be running a
547
fake Mandos client with the keys from the non-encrypted
548
initial <acronym>RAM</acronym> image of the client host. What
549
should be done in that case (if restarting the server program
550
really is necessary) is to stop the server program, edit the
551
configuration file to omit any suspect clients, and restart
555
For more details on client-side security, see
556
<citerefentry><refentrytitle>mandos-client</refentrytitle>
557
<manvolnum>8mandos</manvolnum></citerefentry>.
562
<refsect1 id="see_also">
563
<title>SEE ALSO</title>
566
<refentrytitle>mandos-clients.conf</refentrytitle>
567
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
568
<refentrytitle>mandos.conf</refentrytitle>
569
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
570
<refentrytitle>mandos-client</refentrytitle>
571
<manvolnum>8mandos</manvolnum></citerefentry>, <citerefentry>
572
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
578
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
582
Zeroconf is the network protocol standard used by clients
583
for finding this Mandos server on the local network.
589
<ulink url="http://www.avahi.org/">Avahi</ulink>
593
Avahi is the library this server calls to implement
594
Zeroconf service announcements.
600
<ulink url="http://www.gnu.org/software/gnutls/"
605
GnuTLS is the library this server uses to implement TLS for
606
communicating securely with the client, and at the same time
607
confidently get the client’s public OpenPGP key.
613
RFC 4291: <citetitle>IP Version 6 Addressing
614
Architecture</citetitle>
619
<term>Section 2.2: <citetitle>Text Representation of
620
Addresses</citetitle></term>
621
<listitem><para/></listitem>
624
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
625
Address</citetitle></term>
626
<listitem><para/></listitem>
629
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
630
Addresses</citetitle></term>
633
The clients use IPv6 link-local addresses, which are
634
immediately usable since a link-local addresses is
635
automatically assigned to a network interfaces when it
645
RFC 4346: <citetitle>The Transport Layer Security (TLS)
646
Protocol Version 1.1</citetitle>
650
TLS 1.1 is the protocol implemented by GnuTLS.
656
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
660
The data sent to clients is binary encrypted OpenPGP data.
666
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
671
This is implemented by GnuTLS and used by this server so
672
that OpenPGP keys can be used.
679
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680
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681
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