49
68
<refname><command>&COMMANDNAME;</command></refname>
51
Gives encrypted passwords to authenticated Mandos clients
70
Sends encrypted passwords to authenticated Mandos clients
57
76
<command>&COMMANDNAME;</command>
59
<arg choice="plain"><option>--interface
60
<replaceable>NAME</replaceable></option></arg>
61
<arg choice="plain"><option>-i
62
<replaceable>NAME</replaceable></option></arg>
66
<arg choice="plain"><option>--address
67
<replaceable>ADDRESS</replaceable></option></arg>
68
<arg choice="plain"><option>-a
69
<replaceable>ADDRESS</replaceable></option></arg>
73
<arg choice="plain"><option>--port
74
<replaceable>PORT</replaceable></option></arg>
75
<arg choice="plain"><option>-p
76
<replaceable>PORT</replaceable></option></arg>
79
<arg><option>--priority
80
<replaceable>PRIORITY</replaceable></option></arg>
82
<arg><option>--servicename
83
<replaceable>NAME</replaceable></option></arg>
85
<arg><option>--configdir
86
<replaceable>DIRECTORY</replaceable></option></arg>
88
<arg><option>--debug</option></arg>
90
<arg><option>--debuglevel
91
<replaceable>LEVEL</replaceable></option></arg>
93
<arg><option>--no-dbus</option></arg>
95
<arg><option>--no-ipv6</option></arg>
98
<command>&COMMANDNAME;</command>
100
<arg choice="plain"><option>--help</option></arg>
101
<arg choice="plain"><option>-h</option></arg>
105
<command>&COMMANDNAME;</command>
106
<arg choice="plain"><option>--version</option></arg>
109
<command>&COMMANDNAME;</command>
110
<arg choice="plain"><option>--check</option></arg>
77
<arg choice='opt'>--interface<arg choice='plain'>IF</arg></arg>
78
<arg choice='opt'>--address<arg choice='plain'>ADDRESS</arg></arg>
79
<arg choice='opt'>--port<arg choice='plain'>PORT</arg></arg>
80
<arg choice='opt'>--priority<arg choice='plain'>PRIORITY</arg></arg>
81
<arg choice='opt'>--servicename<arg choice='plain'>NAME</arg></arg>
82
<arg choice='opt'>--configdir<arg choice='plain'>DIRECTORY</arg></arg>
83
<arg choice='opt'>--debug</arg>
86
<command>&COMMANDNAME;</command>
87
<arg choice='opt'>-i<arg choice='plain'>IF</arg></arg>
88
<arg choice='opt'>-a<arg choice='plain'>ADDRESS</arg></arg>
89
<arg choice='opt'>-p<arg choice='plain'>PORT</arg></arg>
90
<arg choice='opt'>--priority<arg choice='plain'>PRIORITY</arg></arg>
91
<arg choice='opt'>--servicename<arg choice='plain'>NAME</arg></arg>
92
<arg choice='opt'>--configdir<arg choice='plain'>DIRECTORY</arg></arg>
93
<arg choice='opt'>--debug</arg>
96
<command>&COMMANDNAME;</command>
97
<arg choice='plain'>--help</arg>
100
<command>&COMMANDNAME;</command>
101
<arg choice='plain'>--version</arg>
104
<command>&COMMANDNAME;</command>
105
<arg choice='plain'>--check</arg>
112
107
</refsynopsisdiv>
114
109
<refsect1 id="description">
115
110
<title>DESCRIPTION</title>
117
112
<command>&COMMANDNAME;</command> is a server daemon which
118
113
handles incoming request for passwords for a pre-defined list of
119
114
client host computers. The Mandos server uses Zeroconf to
120
announce itself on the local network, and uses TLS to
121
communicate securely with and to authenticate the clients. The
122
Mandos server uses IPv6 to allow Mandos clients to use IPv6
123
link-local addresses, since the clients will probably not have
124
any other addresses configured (see <xref linkend="overview"/>).
125
Any authenticated client is then given the stored pre-encrypted
126
password for that specific client.
115
announce itself on the local network, and uses GnuTLS to
116
communicate securely with and to authenticate the clients.
117
Mandos uses IPv6 link-local addresses, since the clients are
118
assumed to not have any other addresses configured yet. Any
119
authenticated client is then given the pre-encrypted password
120
for that specific client.
130
125
<refsect1 id="purpose">
131
126
<title>PURPOSE</title>
133
129
The purpose of this is to enable <emphasis>remote and unattended
134
rebooting</emphasis> of client host computer with an
135
<emphasis>encrypted root file system</emphasis>. See <xref
136
linkend="overview"/> for details.
130
rebooting</emphasis> of any client host computer with an
131
<emphasis>encrypted root file system</emphasis>. The client
132
host computer should start a Mandos client in the initial RAM
133
disk environment, the Mandos client program communicates with
134
this server program to get an encrypted password, which is then
135
decrypted and used to unlock the encrypted root file system.
136
The client host computer can then continue its boot sequence
140
142
<refsect1 id="options">
141
143
<title>OPTIONS</title>
144
<term><option>--help</option></term>
145
<term><option>-h</option></term>
147
<term><literal>-h</literal>, <literal>--help</literal></term>
148
150
Show a help message and exit
154
<term><option>--interface</option>
155
<replaceable>NAME</replaceable></term>
156
<term><option>-i</option>
157
<replaceable>NAME</replaceable></term>
159
<xi:include href="mandos-options.xml" xpointer="interface"/>
164
<term><option>--address
165
<replaceable>ADDRESS</replaceable></option></term>
167
<replaceable>ADDRESS</replaceable></option></term>
169
<xi:include href="mandos-options.xml" xpointer="address"/>
175
<replaceable>PORT</replaceable></option></term>
177
<replaceable>PORT</replaceable></option></term>
179
<xi:include href="mandos-options.xml" xpointer="port"/>
184
<term><option>--check</option></term>
187
Run the server’s self-tests. This includes any unit
156
<term><literal>-i</literal>, <literal>--interface <replaceable>
157
IF</replaceable></literal></term>
160
Only announce the server and listen to requests on network
161
interface <replaceable>IF</replaceable>. Default is to
162
use all available interfaces.
168
<term><literal>-a</literal>, <literal>--address <replaceable>
169
ADDRESS</replaceable></literal></term>
172
If this option is used, the server will only listen to a
173
specific address. This must currently be an IPv6 address;
174
an IPv4 address can be specified using the
175
"<literal>::FFFF:192.0.2.3</literal>" syntax. Also, if a
176
link-local address is specified, an interface should be
177
set, since a link-local address is only valid on a single
178
interface. By default, the server will listen to all
185
<term><literal>-p</literal>, <literal>--port <replaceable>
186
PORT</replaceable></literal></term>
189
If this option is used, the server to bind to that
190
port. By default, the server will listen to an arbitrary
191
port given by the operating system.
197
<term><literal>--check</literal></term>
200
Run the server's self-tests. This includes any unit
194
<term><option>--debug</option></term>
196
<xi:include href="mandos-options.xml" xpointer="debug"/>
201
<term><option>--debuglevel
202
<replaceable>LEVEL</replaceable></option></term>
205
Set the debugging log level.
206
<replaceable>LEVEL</replaceable> is a string, one of
207
<quote><literal>CRITICAL</literal></quote>,
208
<quote><literal>ERROR</literal></quote>,
209
<quote><literal>WARNING</literal></quote>,
210
<quote><literal>INFO</literal></quote>, or
211
<quote><literal>DEBUG</literal></quote>, in order of
212
increasing verbosity. The default level is
213
<quote><literal>WARNING</literal></quote>.
219
<term><option>--priority <replaceable>
220
PRIORITY</replaceable></option></term>
222
<xi:include href="mandos-options.xml" xpointer="priority"/>
227
<term><option>--servicename
228
<replaceable>NAME</replaceable></option></term>
230
<xi:include href="mandos-options.xml"
231
xpointer="servicename"/>
236
<term><option>--configdir
237
<replaceable>DIRECTORY</replaceable></option></term>
207
<term><literal>--debug</literal></term>
210
If the server is run in debug mode, it will run in the
211
foreground and print a lot of debugging information. The
212
default is <emphasis>not</emphasis> to run in debug mode.
218
<term><literal>--priority <replaceable>
219
PRIORITY</replaceable></literal></term>
222
GnuTLS priority string for the TLS handshake with the
224
<citerefentry><refentrytitle>gnutls_priority_init
225
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
226
for the syntax. The default is
227
"<literal>SECURE256:!CTYPE-X.509:+CTYPE-OPENPGP</literal>".
228
<emphasis>Warning</emphasis>: changing this may make the
229
TLS handshake fail, making communication with clients
236
<term><literal>--servicename <replaceable>NAME</replaceable>
240
Zeroconf service name. The default is
241
"<literal>Mandos</literal>". You only need to change this
242
if you for some reason want to run more than one server on
243
the same <emphasis>host</emphasis>. If there are name
244
collisions on the same <emphasis>network</emphasis>, the
245
new server will automatically rename itself to "Mandos
252
<term><literal>--configdir <replaceable>DIR</replaceable>
240
256
Directory to search for configuration files. Default is
241
<quote><literal>/etc/mandos</literal></quote>. See
242
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
257
"<literal>/etc/mandos</literal>". See <citerefentry>
258
<refentrytitle>mandos.conf</refentrytitle>
243
259
<manvolnum>5</manvolnum></citerefentry> and <citerefentry>
244
260
<refentrytitle>mandos-clients.conf</refentrytitle>
245
261
<manvolnum>5</manvolnum></citerefentry>.
251
<term><option>--version</option></term>
267
<term><literal>--version</literal></term>
254
270
Prints the program version and exit.
260
<term><option>--no-dbus</option></term>
262
<xi:include href="mandos-options.xml" xpointer="dbus"/>
264
See also <xref linkend="dbus_interface"/>.
270
<term><option>--no-ipv6</option></term>
272
<xi:include href="mandos-options.xml" xpointer="ipv6"/>
278
<refsect1 id="overview">
279
<title>OVERVIEW</title>
280
<xi:include href="overview.xml"/>
282
This program is the server part. It is a normal server program
283
and will run in a normal system environment, not in an initial
284
<acronym>RAM</acronym> disk environment.
288
277
<refsect1 id="protocol">
289
278
<title>NETWORK PROTOCOL</title>
291
280
The Mandos server announces itself as a Zeroconf service of type
292
<quote><literal>_mandos._tcp</literal></quote>. The Mandos
293
client connects to the announced address and port, and sends a
294
line of text where the first whitespace-separated field is the
295
protocol version, which currently is
296
<quote><literal>1</literal></quote>. The client and server then
297
start a TLS protocol handshake with a slight quirk: the Mandos
298
server program acts as a TLS <quote>client</quote> while the
299
connecting Mandos client acts as a TLS <quote>server</quote>.
300
The Mandos client must supply an OpenPGP certificate, and the
301
fingerprint of this certificate is used by the Mandos server to
302
look up (in a list read from <filename>clients.conf</filename>
303
at start time) which binary blob to give the client. No other
304
authentication or authorization is done by the server.
281
"<literal>_mandos._tcp</literal>". The Mandos client connects
282
to the announced address and port, and sends a line of text
283
where the first whitespace-separated field is the protocol
284
version, which currently is "<literal>1</literal>". The client
285
and server then start a TLS protocol handshake with a slight
286
quirk: the Mandos server program acts as a TLS "client" while
287
the connecting Mandos client acts as a TLS "server". The Mandos
288
client must supply an OpenPGP certificate, and the fingerprint
289
of this certificate is used by the Mandos server to look up (in
290
a list read from a file at start time) which binary blob to give
291
the client. No other authentication or authorization is done by
307
<title>Mandos Protocol (Version 1)</title><tgroup cols="3"><thead>
294
<informaltable><tgroup cols="3"><thead>
309
296
<entry>Mandos Client</entry>
310
297
<entry>Direction</entry>
335
320
<entry><-<!-- ← --></entry>
336
<entry>Binary blob (client will assume OpenPGP data)</entry>
321
<entry>Binary blob</entry>
340
325
<entry><-<!-- ← --></entry>
341
326
<entry>Close</entry>
343
</tbody></tgroup></table>
346
<refsect1 id="checking">
347
<title>CHECKING</title>
349
The server will, by default, continually check that the clients
350
are still up. If a client has not been confirmed as being up
351
for some time, the client is assumed to be compromised and is no
352
longer eligible to receive the encrypted password. (Manual
353
intervention is required to re-enable a client.) The timeout,
354
checker program, and interval between checks can be configured
355
both globally and per client; see <citerefentry>
356
<refentrytitle>mandos-clients.conf</refentrytitle>
357
<manvolnum>5</manvolnum></citerefentry>. A client successfully
358
receiving its password will also be treated as a successful
363
<refsect1 id="approval">
364
<title>APPROVAL</title>
366
The server can be configured to require manual approval for a
367
client before it is sent its secret. The delay to wait for such
368
approval and the default action (approve or deny) can be
369
configured both globally and per client; see <citerefentry>
370
<refentrytitle>mandos-clients.conf</refentrytitle>
371
<manvolnum>5</manvolnum></citerefentry>. By default all clients
372
will be approved immediately without delay.
375
This can be used to deny a client its secret if not manually
376
approved within a specified time. It can also be used to make
377
the server delay before giving a client its secret, allowing
378
optional manual denying of this specific client.
328
</tbody></tgroup></informaltable>
383
331
<refsect1 id="logging">
384
332
<title>LOGGING</title>
386
The server will send log message with various severity levels to
387
<filename>/dev/log</filename>. With the
334
The server will log a lot of information with various severity
336
<citerefentry><refentrytitle>syslog</refentrytitle>
337
<manvolnum>8</manvolnum></citerefentry>. With the
388
338
<option>--debug</option> option, it will log even more messages,
389
339
and also show them on the console.
393
<refsect1 id="dbus_interface">
394
<title>D-BUS INTERFACE</title>
396
The server will by default provide a D-Bus system bus interface.
397
This interface will only be accessible by the root user or a
398
Mandos-specific user, if such a user exists. For documentation
399
of the D-Bus API, see the file <filename>DBUS-API</filename>.
403
343
<refsect1 id="exit_status">
404
344
<title>EXIT STATUS</title>
407
347
critical error is encountered.
411
<refsect1 id="environment">
412
<title>ENVIRONMENT</title>
415
<term><envar>PATH</envar></term>
418
To start the configured checker (see <xref
419
linkend="checking"/>), the server uses
420
<filename>/bin/sh</filename>, which in turn uses
421
<varname>PATH</varname> to search for matching commands if
422
an absolute path is not given. See <citerefentry>
423
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
431
<refsect1 id="files">
432
352
<title>FILES</title>
434
Use the <option>--configdir</option> option to change where
435
<command>&COMMANDNAME;</command> looks for its configurations
436
files. The default file names are listed here.
356
<filename>/etc/mandos/mandos.conf</filename> See <citerefentry>
357
<refentrytitle>mandos.conf</refentrytitle>
358
<manvolnum>5</manvolnum></citerefentry>.
361
<filename>/etc/mandos/clients.conf</filename> See <citerefentry>
362
<refentrytitle>mandos-clients.conf</refentrytitle>
363
<manvolnum>5</manvolnum></citerefentry>.
366
<filename>/var/run/mandos/mandos.pid</filename>
440
<term><filename>/etc/mandos/mandos.conf</filename></term>
443
Server-global settings. See
444
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
445
<manvolnum>5</manvolnum></citerefentry> for details.
450
<term><filename>/etc/mandos/clients.conf</filename></term>
453
List of clients and client-specific settings. See
454
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
455
<manvolnum>5</manvolnum></citerefentry> for details.
460
<term><filename>/var/run/mandos.pid</filename></term>
463
The file containing the process id of the
464
<command>&COMMANDNAME;</command> process started last.
469
<term><filename>/dev/log</filename></term>
472
The Unix domain socket to where local syslog messages are
478
<term><filename>/bin/sh</filename></term>
481
This is used to start the configured checker command for
482
each client. See <citerefentry>
483
<refentrytitle>mandos-clients.conf</refentrytitle>
484
<manvolnum>5</manvolnum></citerefentry> for details.
491
372
<refsect1 id="bugs">
492
373
<title>BUGS</title>
494
This server might, on especially fatal errors, emit a Python
495
backtrace. This could be considered a feature.
498
Currently, if a client is disabled due to having timed out, the
499
server does not record this fact onto permanent storage. This
500
has some security implications, see <xref linkend="clients"/>.
503
There is no fine-grained control over logging and debug output.
506
Debug mode is conflated with running in the foreground.
509
The console log messages do not show a time stamp.
512
This server does not check the expire time of clients’ OpenPGP
517
<refsect1 id="example">
518
<title>EXAMPLE</title>
521
Normal invocation needs no options:
524
<userinput>&COMMANDNAME;</userinput>
529
Run the server in debug mode, read configuration files from
530
the <filename>~/mandos</filename> directory, and use the
531
Zeroconf service name <quote>Test</quote> to not collide with
532
any other official Mandos server on this host:
536
<!-- do not wrap this line -->
537
<userinput>&COMMANDNAME; --debug --configdir ~/mandos --servicename Test</userinput>
543
Run the server normally, but only listen to one interface and
544
only on the link-local address on that interface:
548
<!-- do not wrap this line -->
549
<userinput>&COMMANDNAME; --interface eth7 --address fe80::aede:48ff:fe71:f6f2</userinput>
378
<refsect1 id="examples">
379
<title>EXAMPLES</title>
555
384
<refsect1 id="security">
556
385
<title>SECURITY</title>
557
<refsect2 id="server">
558
<title>SERVER</title>
560
Running this <command>&COMMANDNAME;</command> server program
561
should not in itself present any security risk to the host
562
computer running it. The program switches to a non-root user
566
<refsect2 id="clients">
567
<title>CLIENTS</title>
569
The server only gives out its stored data to clients which
570
does have the OpenPGP key of the stored fingerprint. This is
571
guaranteed by the fact that the client sends its OpenPGP
572
public key in the TLS handshake; this ensures it to be
573
genuine. The server computes the fingerprint of the key
574
itself and looks up the fingerprint in its list of
575
clients. The <filename>clients.conf</filename> file (see
576
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
577
<manvolnum>5</manvolnum></citerefentry>)
578
<emphasis>must</emphasis> be made non-readable by anyone
579
except the user starting the server (usually root).
582
As detailed in <xref linkend="checking"/>, the status of all
583
client computers will continually be checked and be assumed
584
compromised if they are gone for too long.
587
If a client is compromised, its downtime should be duly noted
588
by the server which would therefore disable the client. But
589
if the server was ever restarted, it would re-read its client
590
list from its configuration file and again regard all clients
591
therein as enabled, and hence eligible to receive their
592
passwords. Therefore, be careful when restarting servers if
593
it is suspected that a client has, in fact, been compromised
594
by parties who may now be running a fake Mandos client with
595
the keys from the non-encrypted initial <acronym>RAM</acronym>
596
image of the client host. What should be done in that case
597
(if restarting the server program really is necessary) is to
598
stop the server program, edit the configuration file to omit
599
any suspect clients, and restart the server program.
602
For more details on client-side security, see
603
<citerefentry><refentrytitle>mandos-client</refentrytitle>
604
<manvolnum>8mandos</manvolnum></citerefentry>.
609
390
<refsect1 id="see_also">
610
391
<title>SEE ALSO</title>
613
<refentrytitle>mandos-clients.conf</refentrytitle>
614
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
615
<refentrytitle>mandos.conf</refentrytitle>
616
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
617
<refentrytitle>mandos-client</refentrytitle>
618
<manvolnum>8mandos</manvolnum></citerefentry>, <citerefentry>
619
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
625
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
629
Zeroconf is the network protocol standard used by clients
630
for finding this Mandos server on the local network.
636
<ulink url="http://www.avahi.org/">Avahi</ulink>
640
Avahi is the library this server calls to implement
641
Zeroconf service announcements.
647
<ulink url="http://www.gnu.org/software/gnutls/"
652
GnuTLS is the library this server uses to implement TLS for
653
communicating securely with the client, and at the same time
654
confidently get the client’s public OpenPGP key.
660
RFC 4291: <citetitle>IP Version 6 Addressing
661
Architecture</citetitle>
666
<term>Section 2.2: <citetitle>Text Representation of
667
Addresses</citetitle></term>
668
<listitem><para/></listitem>
671
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
672
Address</citetitle></term>
673
<listitem><para/></listitem>
676
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
677
Addresses</citetitle></term>
680
The clients use IPv6 link-local addresses, which are
681
immediately usable since a link-local addresses is
682
automatically assigned to a network interfaces when it
692
RFC 4346: <citetitle>The Transport Layer Security (TLS)
693
Protocol Version 1.1</citetitle>
697
TLS 1.1 is the protocol implemented by GnuTLS.
703
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
707
The data sent to clients is binary encrypted OpenPGP data.
713
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
718
This is implemented by GnuTLS and used by this server so
719
that OpenPGP keys can be used.
392
<itemizedlist spacing="compact">
394
<citerefentry><refentrytitle>password-request</refentrytitle>
395
<manvolnum>8mandos</manvolnum></citerefentry>
399
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
400
<manvolnum>8mandos</manvolnum></citerefentry>
404
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
408
<ulink url="http://www.avahi.org/">Avahi</ulink>
413
url="http://www.gnu.org/software/gnutls/">GnuTLS</ulink>
417
<citation>RFC 4880: <citetitle>OpenPGP Message
418
Format</citetitle></citation>
422
<citation>RFC 5081: <citetitle>Using OpenPGP Keys for
423
Transport Layer Security</citetitle></citation>
427
<citation>RFC 4291: <citetitle>IP Version 6 Addressing
428
Architecture</citetitle>, section 2.5.6, Link-Local IPv6
429
Unicast Addresses</citation>
726
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