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>
90
<command>&COMMANDNAME;</command>
92
<arg choice="plain"><option>--help</option></arg>
93
<arg choice="plain"><option>-h</option></arg>
97
<command>&COMMANDNAME;</command>
98
<arg choice="plain"><option>--version</option></arg>
101
<command>&COMMANDNAME;</command>
102
<arg choice="plain"><option>--check</option></arg>
107
104
</refsynopsisdiv>
109
106
<refsect1 id="description">
110
107
<title>DESCRIPTION</title>
112
109
<command>&COMMANDNAME;</command> is a server daemon which
113
110
handles incoming request for passwords for a pre-defined list of
114
111
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.
112
announce itself on the local network, and uses TLS to
113
communicate securely with and to authenticate the clients. The
114
Mandos server uses IPv6 to allow Mandos clients to use IPv6
115
link-local addresses, since the clients will probably not have
116
any other addresses configured (see <xref linkend="overview"/>).
117
Any authenticated client is then given the stored pre-encrypted
118
password for that specific client.
125
122
<refsect1 id="purpose">
126
123
<title>PURPOSE</title>
129
125
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
126
rebooting</emphasis> of client host computer with an
127
<emphasis>encrypted root file system</emphasis>. See <xref
128
linkend="overview"/> for details.
142
132
<refsect1 id="options">
143
133
<title>OPTIONS</title>
147
<term><literal>-h</literal>, <literal>--help</literal></term>
136
<term><option>--help</option></term>
137
<term><option>-h</option></term>
150
140
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
146
<term><option>--interface</option>
147
<replaceable>NAME</replaceable></term>
148
<term><option>-i</option>
149
<replaceable>NAME</replaceable></term>
151
<xi:include href="mandos-options.xml" xpointer="interface"/>
156
<term><option>--address
157
<replaceable>ADDRESS</replaceable></option></term>
159
<replaceable>ADDRESS</replaceable></option></term>
161
<xi:include href="mandos-options.xml" xpointer="address"/>
167
<replaceable>PORT</replaceable></option></term>
169
<replaceable>PORT</replaceable></option></term>
171
<xi:include href="mandos-options.xml" xpointer="port"/>
176
<term><option>--check</option></term>
179
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>
186
<term><option>--debug</option></term>
188
<xi:include href="mandos-options.xml" xpointer="debug"/>
193
<term><option>--priority <replaceable>
194
PRIORITY</replaceable></option></term>
196
<xi:include href="mandos-options.xml" xpointer="priority"/>
201
<term><option>--servicename
202
<replaceable>NAME</replaceable></option></term>
204
<xi:include href="mandos-options.xml"
205
xpointer="servicename"/>
210
<term><option>--configdir
211
<replaceable>DIRECTORY</replaceable></option></term>
256
214
Directory to search for configuration files. Default is
257
"<literal>/etc/mandos</literal>". See <citerefentry>
258
<refentrytitle>mandos.conf</refentrytitle>
215
<quote><literal>/etc/mandos</literal></quote>. See
216
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
259
217
<manvolnum>5</manvolnum></citerefentry> and <citerefentry>
260
218
<refentrytitle>mandos-clients.conf</refentrytitle>
261
219
<manvolnum>5</manvolnum></citerefentry>.
267
<term><literal>--version</literal></term>
225
<term><option>--version</option></term>
270
228
Prints the program version and exit.
235
<refsect1 id="overview">
236
<title>OVERVIEW</title>
237
<xi:include href="overview.xml"/>
239
This program is the server part. It is a normal server program
240
and will run in a normal system environment, not in an initial
241
<acronym>RAM</acronym> disk environment.
277
245
<refsect1 id="protocol">
278
246
<title>NETWORK PROTOCOL</title>
280
248
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
249
<quote><literal>_mandos._tcp</literal></quote>. The Mandos
250
client connects to the announced address and port, and sends a
251
line of text where the first whitespace-separated field is the
252
protocol version, which currently is
253
<quote><literal>1</literal></quote>. The client and server then
254
start a TLS protocol handshake with a slight quirk: the Mandos
255
server program acts as a TLS <quote>client</quote> while the
256
connecting Mandos client acts as a TLS <quote>server</quote>.
257
The Mandos client must supply an OpenPGP certificate, and the
258
fingerprint of this certificate is used by the Mandos server to
259
look up (in a list read from <filename>clients.conf</filename>
260
at start time) which binary blob to give the client. No other
261
authentication or authorization is done by the server.
294
<informaltable><tgroup cols="3"><thead>
264
<title>Mandos Protocol (Version 1)</title><tgroup cols="3"><thead>
296
266
<entry>Mandos Client</entry>
297
267
<entry>Direction</entry>
347
331
critical error is encountered.
335
<refsect1 id="environment">
336
<title>ENVIRONMENT</title>
339
<term><envar>PATH</envar></term>
342
To start the configured checker (see <xref
343
linkend="checking"/>), the server uses
344
<filename>/bin/sh</filename>, which in turn uses
345
<varname>PATH</varname> to search for matching commands if
346
an absolute path is not given. See <citerefentry>
347
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
355
<refsect1 id="files">
352
356
<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>
358
Use the <option>--configdir</option> option to change where
359
<command>&COMMANDNAME;</command> looks for its configurations
360
files. The default file names are listed here.
364
<term><filename>/etc/mandos/mandos.conf</filename></term>
367
Server-global settings. See
368
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
369
<manvolnum>5</manvolnum></citerefentry> for details.
374
<term><filename>/etc/mandos/clients.conf</filename></term>
377
List of clients and client-specific settings. See
378
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
379
<manvolnum>5</manvolnum></citerefentry> for details.
384
<term><filename>/var/run/mandos.pid</filename></term>
387
The file containing the process id of
388
<command>&COMMANDNAME;</command>.
393
<term><filename>/dev/log</filename></term>
396
The Unix domain socket to where local syslog messages are
402
<term><filename>/bin/sh</filename></term>
405
This is used to start the configured checker command for
406
each client. See <citerefentry>
362
407
<refentrytitle>mandos-clients.conf</refentrytitle>
363
<manvolnum>5</manvolnum></citerefentry>.
366
<filename>/var/run/mandos/mandos.pid</filename>
408
<manvolnum>5</manvolnum></citerefentry> for details.
372
415
<refsect1 id="bugs">
373
416
<title>BUGS</title>
378
<refsect1 id="examples">
379
<title>EXAMPLES</title>
418
This server might, on especially fatal errors, emit a Python
419
backtrace. This could be considered a feature.
422
Currently, if a client is declared <quote>invalid</quote> due to
423
having timed out, the server does not record this fact onto
424
permanent storage. This has some security implications, see
425
<xref linkend="clients"/>.
428
There is currently no way of querying the server of the current
429
status of clients, other than analyzing its <systemitem
430
class="service">syslog</systemitem> output.
433
There is no fine-grained control over logging and debug output.
436
Debug mode is conflated with running in the foreground.
439
The console log messages does not show a time stamp.
442
This server does not check the expire time of clients’ OpenPGP
447
<refsect1 id="example">
448
<title>EXAMPLE</title>
451
Normal invocation needs no options:
454
<userinput>&COMMANDNAME;</userinput>
459
Run the server in debug mode, read configuration files from
460
the <filename>~/mandos</filename> directory, and use the
461
Zeroconf service name <quote>Test</quote> to not collide with
462
any other official Mandos server on this host:
466
<!-- do not wrap this line -->
467
<userinput>&COMMANDNAME; --debug --configdir ~/mandos --servicename Test</userinput>
473
Run the server normally, but only listen to one interface and
474
only on the link-local address on that interface:
478
<!-- do not wrap this line -->
479
<userinput>&COMMANDNAME; --interface eth7 --address fe80::aede:48ff:fe71:f6f2</userinput>
384
485
<refsect1 id="security">
385
486
<title>SECURITY</title>
487
<refsect2 id="server">
488
<title>SERVER</title>
490
Running this <command>&COMMANDNAME;</command> server program
491
should not in itself present any security risk to the host
492
computer running it. The program switches to a non-root user
496
<refsect2 id="clients">
497
<title>CLIENTS</title>
499
The server only gives out its stored data to clients which
500
does have the OpenPGP key of the stored fingerprint. This is
501
guaranteed by the fact that the client sends its OpenPGP
502
public key in the TLS handshake; this ensures it to be
503
genuine. The server computes the fingerprint of the key
504
itself and looks up the fingerprint in its list of
505
clients. The <filename>clients.conf</filename> file (see
506
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
507
<manvolnum>5</manvolnum></citerefentry>)
508
<emphasis>must</emphasis> be made non-readable by anyone
509
except the user starting the server (usually root).
512
As detailed in <xref linkend="checking"/>, the status of all
513
client computers will continually be checked and be assumed
514
compromised if they are gone for too long.
517
If a client is compromised, its downtime should be duly noted
518
by the server which would therefore declare the client
519
invalid. But if the server was ever restarted, it would
520
re-read its client list from its configuration file and again
521
regard all clients therein as valid, and hence eligible to
522
receive their passwords. Therefore, be careful when
523
restarting servers if it is suspected that a client has, in
524
fact, been compromised by parties who may now be running a
525
fake Mandos client with the keys from the non-encrypted
526
initial <acronym>RAM</acronym> image of the client host. What
527
should be done in that case (if restarting the server program
528
really is necessary) is to stop the server program, edit the
529
configuration file to omit any suspect clients, and restart
533
For more details on client-side security, see
534
<citerefentry><refentrytitle>mandos-client</refentrytitle>
535
<manvolnum>8mandos</manvolnum></citerefentry>.
390
540
<refsect1 id="see_also">
391
541
<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>
544
<refentrytitle>mandos-clients.conf</refentrytitle>
545
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
546
<refentrytitle>mandos.conf</refentrytitle>
547
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
548
<refentrytitle>mandos-client</refentrytitle>
549
<manvolnum>8mandos</manvolnum></citerefentry>, <citerefentry>
550
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
556
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
560
Zeroconf is the network protocol standard used by clients
561
for finding this Mandos server on the local network.
567
<ulink url="http://www.avahi.org/">Avahi</ulink>
571
Avahi is the library this server calls to implement
572
Zeroconf service announcements.
578
<ulink url="http://www.gnu.org/software/gnutls/"
583
GnuTLS is the library this server uses to implement TLS for
584
communicating securely with the client, and at the same time
585
confidently get the client’s public OpenPGP key.
591
RFC 4291: <citetitle>IP Version 6 Addressing
592
Architecture</citetitle>
597
<term>Section 2.2: <citetitle>Text Representation of
598
Addresses</citetitle></term>
599
<listitem><para/></listitem>
602
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
603
Address</citetitle></term>
604
<listitem><para/></listitem>
607
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
608
Addresses</citetitle></term>
611
The clients use IPv6 link-local addresses, which are
612
immediately usable since a link-local addresses is
613
automatically assigned to a network interfaces when it
623
RFC 4346: <citetitle>The Transport Layer Security (TLS)
624
Protocol Version 1.1</citetitle>
628
TLS 1.1 is the protocol implemented by GnuTLS.
634
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
638
The data sent to clients is binary encrypted OpenPGP data.
644
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
649
This is implemented by GnuTLS and used by this server so
650
that OpenPGP keys can be used.
657
<!-- Local Variables: -->
658
<!-- time-stamp-start: "<!ENTITY TIMESTAMP [\"']" -->
659
<!-- time-stamp-end: "[\"']>" -->
660
<!-- time-stamp-format: "%:y-%02m-%02d" -->