76
74
<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>
75
<arg>--interface<arg choice="plain">IF</arg></arg>
76
<arg>--address<arg choice="plain">ADDRESS</arg></arg>
77
<arg>--port<arg choice="plain">PORT</arg></arg>
78
<arg>--priority<arg choice="plain">PRIORITY</arg></arg>
79
<arg>--servicename<arg choice="plain">NAME</arg></arg>
80
<arg>--configdir<arg choice="plain">DIRECTORY</arg></arg>
84
<command>&COMMANDNAME;</command>
85
<arg>-i<arg choice="plain">IF</arg></arg>
86
<arg>-a<arg choice="plain">ADDRESS</arg></arg>
87
<arg>-p<arg choice="plain">PORT</arg></arg>
88
<arg>--priority<arg choice="plain">PRIORITY</arg></arg>
89
<arg>--servicename<arg choice="plain">NAME</arg></arg>
90
<arg>--configdir<arg choice="plain">DIRECTORY</arg></arg>
94
<command>&COMMANDNAME;</command>
96
<arg choice="plain">-h</arg>
97
<arg choice="plain">--help</arg>
101
<command>&COMMANDNAME;</command>
102
<arg choice="plain">--version</arg>
105
<command>&COMMANDNAME;</command>
106
<arg choice="plain">--check</arg>
107
108
</refsynopsisdiv>
109
110
<refsect1 id="description">
112
113
<command>&COMMANDNAME;</command> is a server daemon which
113
114
handles incoming request for passwords for a pre-defined list of
114
115
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.
116
announce itself on the local network, and uses TLS to
117
communicate securely with and to authenticate the clients. The
118
Mandos server uses IPv6 to allow Mandos clients to use IPv6
119
link-local addresses, since the clients will probably not have
120
any other addresses configured (see <xref linkend="overview"/>).
121
Any authenticated client is then given the stored pre-encrypted
122
password for that specific client.
125
127
<refsect1 id="purpose">
126
128
<title>PURPOSE</title>
129
131
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
132
rebooting</emphasis> of client host computer with an
133
<emphasis>encrypted root file system</emphasis>. See <xref
134
linkend="overview"/> for details.
142
139
<refsect1 id="options">
143
140
<title>OPTIONS</title>
156
153
<term><literal>-i</literal>, <literal>--interface <replaceable>
157
154
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.
156
<xi:include href="mandos-options.xml" xpointer="interface"/>
168
161
<term><literal>-a</literal>, <literal>--address <replaceable>
169
162
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
164
<xi:include href="mandos-options.xml" xpointer="address"/>
185
169
<term><literal>-p</literal>, <literal>--port <replaceable>
186
170
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.
172
<xi:include href="mandos-options.xml" xpointer="port"/>
197
177
<term><literal>--check</literal></term>
200
Run the server's self-tests. This includes any unit
180
Run the server’s self-tests. This includes any unit
207
187
<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.
189
<xi:include href="mandos-options.xml" xpointer="debug"/>
270
229
Prints the program version and exit.
236
<refsect1 id="overview">
237
<title>OVERVIEW</title>
238
<xi:include href="overview.xml"/>
240
This program is the server part. It is a normal server program
241
and will run in a normal system environment, not in an initial
242
RAM disk environment.
277
246
<refsect1 id="protocol">
278
247
<title>NETWORK PROTOCOL</title>
280
249
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
250
<quote><literal>_mandos._tcp</literal></quote>. The Mandos
251
client connects to the announced address and port, and sends a
252
line of text where the first whitespace-separated field is the
253
protocol version, which currently is
254
<quote><literal>1</literal></quote>. The client and server then
255
start a TLS protocol handshake with a slight quirk: the Mandos
256
server program acts as a TLS <quote>client</quote> while the
257
connecting Mandos client acts as a TLS <quote>server</quote>.
258
The Mandos client must supply an OpenPGP certificate, and the
259
fingerprint of this certificate is used by the Mandos server to
260
look up (in a list read from <filename>clients.conf</filename>
261
at start time) which binary blob to give the client. No other
262
authentication or authorization is done by the server.
294
<informaltable><tgroup cols="3"><thead>
265
<title>Mandos Protocol (Version 1)</title><tgroup cols="3"><thead>
296
267
<entry>Mandos Client</entry>
297
268
<entry>Direction</entry>
338
<refsect1 id="environment">
339
<title>ENVIRONMENT</title>
342
<term><varname>PATH</varname></term>
345
To start the configured checker (see <xref
346
linkend="checking"/>), the server uses
347
<filename>/bin/sh</filename>, which in turn uses
348
<varname>PATH</varname> to search for matching commands if
349
an absolute path is not given. See <citerefentry>
350
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
351
358
<refsect1 id="file">
352
359
<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>
361
Use the <option>--configdir</option> option to change where
362
<command>&COMMANDNAME;</command> looks for its configurations
363
files. The default file names are listed here.
367
<term><filename>/etc/mandos/mandos.conf</filename></term>
370
Server-global settings. See
371
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
372
<manvolnum>5</manvolnum></citerefentry> for details.
377
<term><filename>/etc/mandos/clients.conf</filename></term>
380
List of clients and client-specific settings. See
381
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
382
<manvolnum>5</manvolnum></citerefentry> for details.
387
<term><filename>/var/run/mandos/mandos.pid</filename></term>
390
The file containing the process id of
391
<command>&COMMANDNAME;</command>.
396
<term><filename>/dev/log</filename></term>
399
The Unix domain socket to where local syslog messages are
405
<term><filename>/bin/sh</filename></term>
408
This is used to start the configured checker command for
409
each client. See <citerefentry>
362
410
<refentrytitle>mandos-clients.conf</refentrytitle>
363
<manvolnum>5</manvolnum></citerefentry>.
366
<filename>/var/run/mandos/mandos.pid</filename>
411
<manvolnum>5</manvolnum></citerefentry> for details.
372
418
<refsect1 id="bugs">
373
419
<title>BUGS</title>
378
<refsect1 id="examples">
379
<title>EXAMPLES</title>
421
This server might, on especially fatal errors, emit a Python
422
backtrace. This could be considered a feature.
425
Currently, if a client is declared <quote>invalid</quote> due to
426
having timed out, the server does not record this fact onto
427
permanent storage. This has some security implications, see
428
<xref linkend="CLIENTS"/>.
431
There is currently no way of querying the server of the current
432
status of clients, other than analyzing its <systemitem
433
class="service">syslog</systemitem> output.
436
There is no fine-grained control over logging and debug output.
439
Debug mode is conflated with running in the foreground.
442
The console log messages does not show a timestamp.
446
<refsect1 id="example">
447
<title>EXAMPLE</title>
450
Normal invocation needs no options:
453
<userinput>mandos</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>mandos --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>mandos --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 does not need any special
492
privileges to run, and is designed to run as 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 running the server.
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 RAM image of the client host. What should be done in
526
that case (if restarting the server program really is
527
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>password-request</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>
545
<refentrytitle>password-request</refentrytitle>
546
<manvolnum>8mandos</manvolnum>
551
This is the actual program which talks to this server.
552
Note that it is normally not invoked directly, and is only
553
run in the initial RAM disk environment, and not on a
554
fully started system.
560
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
564
Zeroconf is the network protocol standard used by clients
565
for finding this Mandos server on the local network.
571
<ulink url="http://www.avahi.org/">Avahi</ulink>
575
Avahi is the library this server calls to implement
576
Zeroconf service announcements.
583
url="http://www.gnu.org/software/gnutls/">GnuTLS</ulink>
587
GnuTLS is the library this server uses to implement TLS for
588
communicating securely with the client, and at the same time
589
confidently get the client’s public OpenPGP key.
595
<citation>RFC 4291: <citetitle>IP Version 6 Addressing
596
Architecture</citetitle>, section 2.5.6, Link-Local IPv6
597
Unicast Addresses</citation>
601
The clients use IPv6 link-local addresses, which are
602
immediately usable since a link-local addresses is
603
automatically assigned to a network interfaces when it is
610
<citation>RFC 4346: <citetitle>The Transport Layer Security
611
(TLS) Protocol Version 1.1</citetitle></citation>
615
TLS 1.1 is the protocol implemented by GnuTLS.
621
<citation>RFC 4880: <citetitle>OpenPGP Message
622
Format</citetitle></citation>
626
The data sent to clients is binary encrypted OpenPGP data.
632
<citation>RFC 5081: <citetitle>Using OpenPGP Keys for
633
Transport Layer Security</citetitle></citation>
637
This is implemented by GnuTLS and used by this server so
638
that OpenPGP keys can be used.