68
48
<refname><command>&COMMANDNAME;</command></refname>
70
Sends encrypted passwords to authenticated Mandos clients
50
Gives encrypted passwords to authenticated Mandos clients
76
56
<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>
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>
107
106
</refsynopsisdiv>
109
108
<refsect1 id="description">
110
109
<title>DESCRIPTION</title>
112
111
<command>&COMMANDNAME;</command> is a server daemon which
113
112
handles incoming request for passwords for a pre-defined list of
114
113
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.
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.
125
124
<refsect1 id="purpose">
126
125
<title>PURPOSE</title>
129
127
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
128
rebooting</emphasis> of client host computer with an
129
<emphasis>encrypted root file system</emphasis>. See <xref
130
linkend="overview"/> for details.
142
134
<refsect1 id="options">
143
135
<title>OPTIONS</title>
147
<term><literal>-h</literal>, <literal>--help</literal></term>
138
<term><option>--help</option></term>
139
<term><option>-h</option></term>
150
142
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
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
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>
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>
256
216
Directory to search for configuration files. Default is
257
"<literal>/etc/mandos</literal>". See <citerefentry>
258
<refentrytitle>mandos.conf</refentrytitle>
217
<quote><literal>/etc/mandos</literal></quote>. See
218
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
259
219
<manvolnum>5</manvolnum></citerefentry> and <citerefentry>
260
220
<refentrytitle>mandos-clients.conf</refentrytitle>
261
221
<manvolnum>5</manvolnum></citerefentry>.
267
<term><literal>--version</literal></term>
227
<term><option>--version</option></term>
270
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.
277
257
<refsect1 id="protocol">
278
258
<title>NETWORK PROTOCOL</title>
280
260
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
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.
294
<informaltable><tgroup cols="3"><thead>
276
<title>Mandos Protocol (Version 1)</title><tgroup cols="3"><thead>
296
278
<entry>Mandos Client</entry>
297
279
<entry>Direction</entry>
347
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">
352
378
<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>
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>
362
429
<refentrytitle>mandos-clients.conf</refentrytitle>
363
<manvolnum>5</manvolnum></citerefentry>.
366
<filename>/var/run/mandos/mandos.pid</filename>
430
<manvolnum>5</manvolnum></citerefentry> for details.
372
437
<refsect1 id="bugs">
373
438
<title>BUGS</title>
378
<refsect1 id="examples">
379
<title>EXAMPLES</title>
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>
384
507
<refsect1 id="security">
385
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>.
390
562
<refsect1 id="see_also">
391
563
<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>
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
<!-- Local Variables: -->
680
<!-- time-stamp-start: "<!ENTITY TIMESTAMP [\"']" -->
681
<!-- time-stamp-end: "[\"']>" -->
682
<!-- time-stamp-format: "%:y-%02m-%02d" -->