68
47
<refname><command>&COMMANDNAME;</command></refname>
70
Sends encrypted passwords to authenticated Mandos clients
49
Gives encrypted passwords to authenticated Mandos clients
76
55
<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>
57
<arg choice="plain"><option>--interface
58
<replaceable>NAME</replaceable></option></arg>
59
<arg choice="plain"><option>-i
60
<replaceable>NAME</replaceable></option></arg>
64
<arg choice="plain"><option>--address
65
<replaceable>ADDRESS</replaceable></option></arg>
66
<arg choice="plain"><option>-a
67
<replaceable>ADDRESS</replaceable></option></arg>
71
<arg choice="plain"><option>--port
72
<replaceable>PORT</replaceable></option></arg>
73
<arg choice="plain"><option>-p
74
<replaceable>PORT</replaceable></option></arg>
77
<arg><option>--priority
78
<replaceable>PRIORITY</replaceable></option></arg>
80
<arg><option>--servicename
81
<replaceable>NAME</replaceable></option></arg>
83
<arg><option>--configdir
84
<replaceable>DIRECTORY</replaceable></option></arg>
86
<arg><option>--debug</option></arg>
89
<command>&COMMANDNAME;</command>
91
<arg choice="plain"><option>--help</option></arg>
92
<arg choice="plain"><option>-h</option></arg>
96
<command>&COMMANDNAME;</command>
97
<arg choice="plain"><option>--version</option></arg>
100
<command>&COMMANDNAME;</command>
101
<arg choice="plain"><option>--check</option></arg>
107
103
</refsynopsisdiv>
109
105
<refsect1 id="description">
110
106
<title>DESCRIPTION</title>
112
108
<command>&COMMANDNAME;</command> is a server daemon which
113
109
handles incoming request for passwords for a pre-defined list of
114
110
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.
111
announce itself on the local network, and uses TLS to
112
communicate securely with and to authenticate the clients. The
113
Mandos server uses IPv6 to allow Mandos clients to use IPv6
114
link-local addresses, since the clients will probably not have
115
any other addresses configured (see <xref linkend="overview"/>).
116
Any authenticated client is then given the stored pre-encrypted
117
password for that specific client.
125
121
<refsect1 id="purpose">
126
122
<title>PURPOSE</title>
129
124
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
125
rebooting</emphasis> of client host computer with an
126
<emphasis>encrypted root file system</emphasis>. See <xref
127
linkend="overview"/> for details.
142
131
<refsect1 id="options">
143
132
<title>OPTIONS</title>
147
<term><literal>-h</literal>, <literal>--help</literal></term>
135
<term><option>--help</option></term>
136
<term><option>-h</option></term>
150
139
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
145
<term><option>--interface</option>
146
<replaceable>NAME</replaceable></term>
147
<term><option>-i</option>
148
<replaceable>NAME</replaceable></term>
150
<xi:include href="mandos-options.xml" xpointer="interface"/>
155
<term><option>--address
156
<replaceable>ADDRESS</replaceable></option></term>
158
<replaceable>ADDRESS</replaceable></option></term>
160
<xi:include href="mandos-options.xml" xpointer="address"/>
166
<replaceable>PORT</replaceable></option></term>
168
<replaceable>PORT</replaceable></option></term>
170
<xi:include href="mandos-options.xml" xpointer="port"/>
175
<term><option>--check</option></term>
178
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>
185
<term><option>--debug</option></term>
187
<xi:include href="mandos-options.xml" xpointer="debug"/>
192
<term><option>--priority <replaceable>
193
PRIORITY</replaceable></option></term>
195
<xi:include href="mandos-options.xml" xpointer="priority"/>
200
<term><option>--servicename
201
<replaceable>NAME</replaceable></option></term>
203
<xi:include href="mandos-options.xml"
204
xpointer="servicename"/>
209
<term><option>--configdir
210
<replaceable>DIRECTORY</replaceable></option></term>
256
213
Directory to search for configuration files. Default is
257
"<literal>/etc/mandos</literal>". See <citerefentry>
258
<refentrytitle>mandos.conf</refentrytitle>
214
<quote><literal>/etc/mandos</literal></quote>. See
215
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
259
216
<manvolnum>5</manvolnum></citerefentry> and <citerefentry>
260
217
<refentrytitle>mandos-clients.conf</refentrytitle>
261
218
<manvolnum>5</manvolnum></citerefentry>.
267
<term><literal>--version</literal></term>
224
<term><option>--version</option></term>
270
227
Prints the program version and exit.
234
<refsect1 id="overview">
235
<title>OVERVIEW</title>
236
<xi:include href="overview.xml"/>
238
This program is the server part. It is a normal server program
239
and will run in a normal system environment, not in an initial
240
<acronym>RAM</acronym> disk environment.
277
244
<refsect1 id="protocol">
278
245
<title>NETWORK PROTOCOL</title>
280
247
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
248
<quote><literal>_mandos._tcp</literal></quote>. The Mandos
249
client connects to the announced address and port, and sends a
250
line of text where the first whitespace-separated field is the
251
protocol version, which currently is
252
<quote><literal>1</literal></quote>. The client and server then
253
start a TLS protocol handshake with a slight quirk: the Mandos
254
server program acts as a TLS <quote>client</quote> while the
255
connecting Mandos client acts as a TLS <quote>server</quote>.
256
The Mandos client must supply an OpenPGP certificate, and the
257
fingerprint of this certificate is used by the Mandos server to
258
look up (in a list read from <filename>clients.conf</filename>
259
at start time) which binary blob to give the client. No other
260
authentication or authorization is done by the server.
294
<informaltable><tgroup cols="3"><thead>
263
<title>Mandos Protocol (Version 1)</title><tgroup cols="3"><thead>
296
265
<entry>Mandos Client</entry>
297
266
<entry>Direction</entry>
347
330
critical error is encountered.
334
<refsect1 id="environment">
335
<title>ENVIRONMENT</title>
338
<term><envar>PATH</envar></term>
341
To start the configured checker (see <xref
342
linkend="checking"/>), the server uses
343
<filename>/bin/sh</filename>, which in turn uses
344
<varname>PATH</varname> to search for matching commands if
345
an absolute path is not given. See <citerefentry>
346
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
354
<refsect1 id="files">
352
355
<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>
357
Use the <option>--configdir</option> option to change where
358
<command>&COMMANDNAME;</command> looks for its configurations
359
files. The default file names are listed here.
363
<term><filename>/etc/mandos/mandos.conf</filename></term>
366
Server-global settings. See
367
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
368
<manvolnum>5</manvolnum></citerefentry> for details.
373
<term><filename>/etc/mandos/clients.conf</filename></term>
376
List of clients and client-specific settings. See
377
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
378
<manvolnum>5</manvolnum></citerefentry> for details.
383
<term><filename>/var/run/mandos.pid</filename></term>
386
The file containing the process id of
387
<command>&COMMANDNAME;</command>.
392
<term><filename>/dev/log</filename></term>
395
The Unix domain socket to where local syslog messages are
401
<term><filename>/bin/sh</filename></term>
404
This is used to start the configured checker command for
405
each client. See <citerefentry>
362
406
<refentrytitle>mandos-clients.conf</refentrytitle>
363
<manvolnum>5</manvolnum></citerefentry>.
366
<filename>/var/run/mandos/mandos.pid</filename>
407
<manvolnum>5</manvolnum></citerefentry> for details.
372
414
<refsect1 id="bugs">
373
415
<title>BUGS</title>
378
<refsect1 id="examples">
379
<title>EXAMPLES</title>
417
This server might, on especially fatal errors, emit a Python
418
backtrace. This could be considered a feature.
421
Currently, if a client is declared <quote>invalid</quote> due to
422
having timed out, the server does not record this fact onto
423
permanent storage. This has some security implications, see
424
<xref linkend="clients"/>.
427
There is currently no way of querying the server of the current
428
status of clients, other than analyzing its <systemitem
429
class="service">syslog</systemitem> output.
432
There is no fine-grained control over logging and debug output.
435
Debug mode is conflated with running in the foreground.
438
The console log messages does not show a time stamp.
441
This server does not check the expire time of clients’ OpenPGP
446
<refsect1 id="example">
447
<title>EXAMPLE</title>
450
Normal invocation needs no options:
453
<userinput>&COMMANDNAME;</userinput>
458
Run the server in debug mode, read configuration files from
459
the <filename>~/mandos</filename> directory, and use the
460
Zeroconf service name <quote>Test</quote> to not collide with
461
any other official Mandos server on this host:
465
<!-- do not wrap this line -->
466
<userinput>&COMMANDNAME; --debug --configdir ~/mandos --servicename Test</userinput>
472
Run the server normally, but only listen to one interface and
473
only on the link-local address on that interface:
477
<!-- do not wrap this line -->
478
<userinput>&COMMANDNAME; --interface eth7 --address fe80::aede:48ff:fe71:f6f2</userinput>
384
484
<refsect1 id="security">
385
485
<title>SECURITY</title>
486
<refsect2 id="server">
487
<title>SERVER</title>
489
Running this <command>&COMMANDNAME;</command> server program
490
should not in itself present any security risk to the host
491
computer running it. The program switches to a non-root user
495
<refsect2 id="clients">
496
<title>CLIENTS</title>
498
The server only gives out its stored data to clients which
499
does have the OpenPGP key of the stored fingerprint. This is
500
guaranteed by the fact that the client sends its OpenPGP
501
public key in the TLS handshake; this ensures it to be
502
genuine. The server computes the fingerprint of the key
503
itself and looks up the fingerprint in its list of
504
clients. The <filename>clients.conf</filename> file (see
505
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
506
<manvolnum>5</manvolnum></citerefentry>)
507
<emphasis>must</emphasis> be made non-readable by anyone
508
except the user starting the server (usually root).
511
As detailed in <xref linkend="checking"/>, the status of all
512
client computers will continually be checked and be assumed
513
compromised if they are gone for too long.
516
If a client is compromised, its downtime should be duly noted
517
by the server which would therefore declare the client
518
invalid. But if the server was ever restarted, it would
519
re-read its client list from its configuration file and again
520
regard all clients therein as valid, and hence eligible to
521
receive their passwords. Therefore, be careful when
522
restarting servers if it is suspected that a client has, in
523
fact, been compromised by parties who may now be running a
524
fake Mandos client with the keys from the non-encrypted
525
initial <acronym>RAM</acronym> image of the client host. What
526
should be done in that case (if restarting the server program
527
really is necessary) is to stop the server program, edit the
528
configuration file to omit any suspect clients, and restart
532
For more details on client-side security, see
533
<citerefentry><refentrytitle>mandos-client</refentrytitle>
534
<manvolnum>8mandos</manvolnum></citerefentry>.
390
539
<refsect1 id="see_also">
391
540
<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>
543
<refentrytitle>mandos-clients.conf</refentrytitle>
544
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
545
<refentrytitle>mandos.conf</refentrytitle>
546
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
547
<refentrytitle>mandos-client</refentrytitle>
548
<manvolnum>8mandos</manvolnum></citerefentry>, <citerefentry>
549
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
555
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
559
Zeroconf is the network protocol standard used by clients
560
for finding this Mandos server on the local network.
566
<ulink url="http://www.avahi.org/">Avahi</ulink>
570
Avahi is the library this server calls to implement
571
Zeroconf service announcements.
577
<ulink url="http://www.gnu.org/software/gnutls/"
582
GnuTLS is the library this server uses to implement TLS for
583
communicating securely with the client, and at the same time
584
confidently get the client’s public OpenPGP key.
590
RFC 4291: <citetitle>IP Version 6 Addressing
591
Architecture</citetitle>
596
<term>Section 2.2: <citetitle>Text Representation of
597
Addresses</citetitle></term>
598
<listitem><para/></listitem>
601
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
602
Address</citetitle></term>
603
<listitem><para/></listitem>
606
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
607
Addresses</citetitle></term>
610
The clients use IPv6 link-local addresses, which are
611
immediately usable since a link-local addresses is
612
automatically assigned to a network interfaces when it
622
RFC 4346: <citetitle>The Transport Layer Security (TLS)
623
Protocol Version 1.1</citetitle>
627
TLS 1.1 is the protocol implemented by GnuTLS.
633
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
637
The data sent to clients is binary encrypted OpenPGP data.
643
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
648
This is implemented by GnuTLS and used by this server so
649
that OpenPGP keys can be used.
656
<!-- Local Variables: -->
657
<!-- time-stamp-start: "<!ENTITY TIMESTAMP [\"']" -->
658
<!-- time-stamp-end: "[\"']>" -->
659
<!-- time-stamp-format: "%:y-%02m-%02d" -->