68
50
<refname><command>&COMMANDNAME;</command></refname>
70
Sends encrypted passwords to authenticated Mandos clients
52
Gives encrypted passwords to authenticated Mandos clients
76
58
<command>&COMMANDNAME;</command>
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>
60
<arg choice="plain"><option>--interface
61
<replaceable>NAME</replaceable></option></arg>
62
<arg choice="plain"><option>-i
63
<replaceable>NAME</replaceable></option></arg>
67
<arg choice="plain"><option>--address
68
<replaceable>ADDRESS</replaceable></option></arg>
69
<arg choice="plain"><option>-a
70
<replaceable>ADDRESS</replaceable></option></arg>
74
<arg choice="plain"><option>--port
75
<replaceable>PORT</replaceable></option></arg>
76
<arg choice="plain"><option>-p
77
<replaceable>PORT</replaceable></option></arg>
80
<arg><option>--priority
81
<replaceable>PRIORITY</replaceable></option></arg>
83
<arg><option>--servicename
84
<replaceable>NAME</replaceable></option></arg>
86
<arg><option>--configdir
87
<replaceable>DIRECTORY</replaceable></option></arg>
89
<arg><option>--debug</option></arg>
91
<arg><option>--debuglevel
92
<replaceable>LEVEL</replaceable></option></arg>
94
<arg><option>--no-dbus</option></arg>
96
<arg><option>--no-ipv6</option></arg>
99
<command>&COMMANDNAME;</command>
101
<arg choice="plain"><option>--help</option></arg>
102
<arg choice="plain"><option>-h</option></arg>
106
<command>&COMMANDNAME;</command>
107
<arg choice="plain"><option>--version</option></arg>
110
<command>&COMMANDNAME;</command>
111
<arg choice="plain"><option>--check</option></arg>
107
113
</refsynopsisdiv>
109
115
<refsect1 id="description">
110
116
<title>DESCRIPTION</title>
112
118
<command>&COMMANDNAME;</command> is a server daemon which
113
119
handles incoming request for passwords for a pre-defined list of
114
120
client host computers. The Mandos server uses Zeroconf to
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.
121
announce itself on the local network, and uses TLS to
122
communicate securely with and to authenticate the clients. The
123
Mandos server uses IPv6 to allow Mandos clients to use IPv6
124
link-local addresses, since the clients will probably not have
125
any other addresses configured (see <xref linkend="overview"/>).
126
Any authenticated client is then given the stored pre-encrypted
127
password for that specific client.
125
131
<refsect1 id="purpose">
126
132
<title>PURPOSE</title>
129
134
The purpose of this is to enable <emphasis>remote and unattended
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
135
rebooting</emphasis> of client host computer with an
136
<emphasis>encrypted root file system</emphasis>. See <xref
137
linkend="overview"/> for details.
142
141
<refsect1 id="options">
143
142
<title>OPTIONS</title>
147
<term><literal>-h</literal>, <literal>--help</literal></term>
145
<term><option>--help</option></term>
146
<term><option>-h</option></term>
150
149
Show a help message and exit
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
155
<term><option>--interface</option>
156
<replaceable>NAME</replaceable></term>
157
<term><option>-i</option>
158
<replaceable>NAME</replaceable></term>
160
<xi:include href="mandos-options.xml" xpointer="interface"/>
165
<term><option>--address
166
<replaceable>ADDRESS</replaceable></option></term>
168
<replaceable>ADDRESS</replaceable></option></term>
170
<xi:include href="mandos-options.xml" xpointer="address"/>
176
<replaceable>PORT</replaceable></option></term>
178
<replaceable>PORT</replaceable></option></term>
180
<xi:include href="mandos-options.xml" xpointer="port"/>
185
<term><option>--check</option></term>
188
Run the server’s self-tests. This includes any unit
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>
195
<term><option>--debug</option></term>
197
<xi:include href="mandos-options.xml" xpointer="debug"/>
202
<term><option>--debuglevel
203
<replaceable>LEVEL</replaceable></option></term>
206
Set the debugging log level.
207
<replaceable>LEVEL</replaceable> is a string, one of
208
<quote><literal>CRITICAL</literal></quote>,
209
<quote><literal>ERROR</literal></quote>,
210
<quote><literal>WARNING</literal></quote>,
211
<quote><literal>INFO</literal></quote>, or
212
<quote><literal>DEBUG</literal></quote>, in order of
213
increasing verbosity. The default level is
214
<quote><literal>WARNING</literal></quote>.
220
<term><option>--priority <replaceable>
221
PRIORITY</replaceable></option></term>
223
<xi:include href="mandos-options.xml" xpointer="priority"/>
228
<term><option>--servicename
229
<replaceable>NAME</replaceable></option></term>
231
<xi:include href="mandos-options.xml"
232
xpointer="servicename"/>
237
<term><option>--configdir
238
<replaceable>DIRECTORY</replaceable></option></term>
256
241
Directory to search for configuration files. Default is
257
"<literal>/etc/mandos</literal>". See <citerefentry>
258
<refentrytitle>mandos.conf</refentrytitle>
242
<quote><literal>/etc/mandos</literal></quote>. See
243
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
259
244
<manvolnum>5</manvolnum></citerefentry> and <citerefentry>
260
245
<refentrytitle>mandos-clients.conf</refentrytitle>
261
246
<manvolnum>5</manvolnum></citerefentry>.
267
<term><literal>--version</literal></term>
252
<term><option>--version</option></term>
270
255
Prints the program version and exit.
261
<term><option>--no-dbus</option></term>
263
<xi:include href="mandos-options.xml" xpointer="dbus"/>
265
See also <xref linkend="dbus_interface"/>.
271
<term><option>--no-ipv6</option></term>
273
<xi:include href="mandos-options.xml" xpointer="ipv6"/>
279
<refsect1 id="overview">
280
<title>OVERVIEW</title>
281
<xi:include href="overview.xml"/>
283
This program is the server part. It is a normal server program
284
and will run in a normal system environment, not in an initial
285
<acronym>RAM</acronym> disk environment.
277
289
<refsect1 id="protocol">
278
290
<title>NETWORK PROTOCOL</title>
280
292
The Mandos server announces itself as a Zeroconf service of type
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
293
<quote><literal>_mandos._tcp</literal></quote>. The Mandos
294
client connects to the announced address and port, and sends a
295
line of text where the first whitespace-separated field is the
296
protocol version, which currently is
297
<quote><literal>1</literal></quote>. The client and server then
298
start a TLS protocol handshake with a slight quirk: the Mandos
299
server program acts as a TLS <quote>client</quote> while the
300
connecting Mandos client acts as a TLS <quote>server</quote>.
301
The Mandos client must supply an OpenPGP certificate, and the
302
fingerprint of this certificate is used by the Mandos server to
303
look up (in a list read from <filename>clients.conf</filename>
304
at start time) which binary blob to give the client. No other
305
authentication or authorization is done by the server.
294
<informaltable><tgroup cols="3"><thead>
308
<title>Mandos Protocol (Version 1)</title><tgroup cols="3"><thead>
296
310
<entry>Mandos Client</entry>
297
311
<entry>Direction</entry>
320
336
<entry><-<!-- ← --></entry>
321
<entry>Binary blob</entry>
337
<entry>Binary blob (client will assume OpenPGP data)</entry>
325
341
<entry><-<!-- ← --></entry>
326
342
<entry>Close</entry>
328
</tbody></tgroup></informaltable>
344
</tbody></tgroup></table>
347
<refsect1 id="checking">
348
<title>CHECKING</title>
350
The server will, by default, continually check that the clients
351
are still up. If a client has not been confirmed as being up
352
for some time, the client is assumed to be compromised and is no
353
longer eligible to receive the encrypted password. (Manual
354
intervention is required to re-enable a client.) The timeout,
355
checker program, and interval between checks can be configured
356
both globally and per client; see <citerefentry>
357
<refentrytitle>mandos-clients.conf</refentrytitle>
358
<manvolnum>5</manvolnum></citerefentry>. A client successfully
359
receiving its password will also be treated as a successful
364
<refsect1 id="approval">
365
<title>APPROVAL</title>
367
The server can be configured to require manual approval for a
368
client before it is sent its secret. The delay to wait for such
369
approval and the default action (approve or deny) can be
370
configured both globally and per client; see <citerefentry>
371
<refentrytitle>mandos-clients.conf</refentrytitle>
372
<manvolnum>5</manvolnum></citerefentry>. By default all clients
373
will be approved immediately without delay.
376
This can be used to deny a client its secret if not manually
377
approved within a specified time. It can also be used to make
378
the server delay before giving a client its secret, allowing
379
optional manual denying of this specific client.
331
384
<refsect1 id="logging">
332
385
<title>LOGGING</title>
334
The server will log a lot of information with various severity
336
<citerefentry><refentrytitle>syslog</refentrytitle>
337
<manvolnum>8</manvolnum></citerefentry>. With the
387
The server will send log message with various severity levels to
388
<filename>/dev/log</filename>. With the
338
389
<option>--debug</option> option, it will log even more messages,
339
390
and also show them on the console.
394
<refsect1 id="dbus_interface">
395
<title>D-BUS INTERFACE</title>
397
The server will by default provide a D-Bus system bus interface.
398
This interface will only be accessible by the root user or a
399
Mandos-specific user, if such a user exists. For documentation
400
of the D-Bus API, see the file <filename>DBUS-API</filename>.
343
404
<refsect1 id="exit_status">
344
405
<title>EXIT STATUS</title>
347
408
critical error is encountered.
412
<refsect1 id="environment">
413
<title>ENVIRONMENT</title>
416
<term><envar>PATH</envar></term>
419
To start the configured checker (see <xref
420
linkend="checking"/>), the server uses
421
<filename>/bin/sh</filename>, which in turn uses
422
<varname>PATH</varname> to search for matching commands if
423
an absolute path is not given. See <citerefentry>
424
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
432
<refsect1 id="files">
352
433
<title>FILES</title>
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>
435
Use the <option>--configdir</option> option to change where
436
<command>&COMMANDNAME;</command> looks for its configurations
437
files. The default file names are listed here.
441
<term><filename>/etc/mandos/mandos.conf</filename></term>
444
Server-global settings. See
445
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
446
<manvolnum>5</manvolnum></citerefentry> for details.
451
<term><filename>/etc/mandos/clients.conf</filename></term>
454
List of clients and client-specific settings. See
455
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
456
<manvolnum>5</manvolnum></citerefentry> for details.
461
<term><filename>/var/run/mandos.pid</filename></term>
464
The file containing the process id of the
465
<command>&COMMANDNAME;</command> process started last.
470
<term><filename>/dev/log</filename></term>
473
The Unix domain socket to where local syslog messages are
479
<term><filename>/bin/sh</filename></term>
482
This is used to start the configured checker command for
483
each client. See <citerefentry>
362
484
<refentrytitle>mandos-clients.conf</refentrytitle>
363
<manvolnum>5</manvolnum></citerefentry>.
366
<filename>/var/run/mandos/mandos.pid</filename>
485
<manvolnum>5</manvolnum></citerefentry> for details.
372
492
<refsect1 id="bugs">
373
493
<title>BUGS</title>
378
<refsect1 id="examples">
379
<title>EXAMPLES</title>
495
This server might, on especially fatal errors, emit a Python
496
backtrace. This could be considered a feature.
499
Currently, if a client is disabled due to having timed out, the
500
server does not record this fact onto permanent storage. This
501
has some security implications, see <xref linkend="clients"/>.
504
There is no fine-grained control over logging and debug output.
507
Debug mode is conflated with running in the foreground.
510
The console log messages do not show a time stamp.
513
This server does not check the expire time of clients’ OpenPGP
518
<refsect1 id="example">
519
<title>EXAMPLE</title>
522
Normal invocation needs no options:
525
<userinput>&COMMANDNAME;</userinput>
530
Run the server in debug mode, read configuration files from
531
the <filename>~/mandos</filename> directory, and use the
532
Zeroconf service name <quote>Test</quote> to not collide with
533
any other official Mandos server on this host:
537
<!-- do not wrap this line -->
538
<userinput>&COMMANDNAME; --debug --configdir ~/mandos --servicename Test</userinput>
544
Run the server normally, but only listen to one interface and
545
only on the link-local address on that interface:
549
<!-- do not wrap this line -->
550
<userinput>&COMMANDNAME; --interface eth7 --address fe80::aede:48ff:fe71:f6f2</userinput>
384
556
<refsect1 id="security">
385
557
<title>SECURITY</title>
558
<refsect2 id="server">
559
<title>SERVER</title>
561
Running this <command>&COMMANDNAME;</command> server program
562
should not in itself present any security risk to the host
563
computer running it. The program switches to a non-root user
567
<refsect2 id="clients">
568
<title>CLIENTS</title>
570
The server only gives out its stored data to clients which
571
does have the OpenPGP key of the stored fingerprint. This is
572
guaranteed by the fact that the client sends its OpenPGP
573
public key in the TLS handshake; this ensures it to be
574
genuine. The server computes the fingerprint of the key
575
itself and looks up the fingerprint in its list of
576
clients. The <filename>clients.conf</filename> file (see
577
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
578
<manvolnum>5</manvolnum></citerefentry>)
579
<emphasis>must</emphasis> be made non-readable by anyone
580
except the user starting the server (usually root).
583
As detailed in <xref linkend="checking"/>, the status of all
584
client computers will continually be checked and be assumed
585
compromised if they are gone for too long.
588
If a client is compromised, its downtime should be duly noted
589
by the server which would therefore disable the client. But
590
if the server was ever restarted, it would re-read its client
591
list from its configuration file and again regard all clients
592
therein as enabled, and hence eligible to receive their
593
passwords. Therefore, be careful when restarting servers if
594
it is suspected that a client has, in fact, been compromised
595
by parties who may now be running a fake Mandos client with
596
the keys from the non-encrypted initial <acronym>RAM</acronym>
597
image of the client host. What should be done in that case
598
(if restarting the server program really is necessary) is to
599
stop the server program, edit the configuration file to omit
600
any suspect clients, and restart the server program.
603
For more details on client-side security, see
604
<citerefentry><refentrytitle>mandos-client</refentrytitle>
605
<manvolnum>8mandos</manvolnum></citerefentry>.
390
610
<refsect1 id="see_also">
391
611
<title>SEE ALSO</title>
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>
614
<refentrytitle>mandos-clients.conf</refentrytitle>
615
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
616
<refentrytitle>mandos.conf</refentrytitle>
617
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
618
<refentrytitle>mandos-client</refentrytitle>
619
<manvolnum>8mandos</manvolnum></citerefentry>, <citerefentry>
620
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
626
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
630
Zeroconf is the network protocol standard used by clients
631
for finding this Mandos server on the local network.
637
<ulink url="http://www.avahi.org/">Avahi</ulink>
641
Avahi is the library this server calls to implement
642
Zeroconf service announcements.
648
<ulink url="http://www.gnu.org/software/gnutls/"
653
GnuTLS is the library this server uses to implement TLS for
654
communicating securely with the client, and at the same time
655
confidently get the client’s public OpenPGP key.
661
RFC 4291: <citetitle>IP Version 6 Addressing
662
Architecture</citetitle>
667
<term>Section 2.2: <citetitle>Text Representation of
668
Addresses</citetitle></term>
669
<listitem><para/></listitem>
672
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
673
Address</citetitle></term>
674
<listitem><para/></listitem>
677
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
678
Addresses</citetitle></term>
681
The clients use IPv6 link-local addresses, which are
682
immediately usable since a link-local addresses is
683
automatically assigned to a network interfaces when it
693
RFC 4346: <citetitle>The Transport Layer Security (TLS)
694
Protocol Version 1.1</citetitle>
698
TLS 1.1 is the protocol implemented by GnuTLS.
704
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
708
The data sent to clients is binary encrypted OpenPGP data.
714
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
719
This is implemented by GnuTLS and used by this server so
720
that OpenPGP keys can be used.
727
<!-- Local Variables: -->
728
<!-- time-stamp-start: "<!ENTITY TIMESTAMP [\"']" -->
729
<!-- time-stamp-end: "[\"']>" -->
730
<!-- time-stamp-format: "%:y-%02m-%02d" -->