67
46
<refname><command>&COMMANDNAME;</command></refname>
69
Sends encrypted passwords to authenticated mandos clients
48
Gives encrypted passwords to authenticated Mandos clients
75
54
<command>&COMMANDNAME;</command>
76
<arg choice='opt'>--interface<arg choice='plain'>IF</arg></arg>
77
<arg choice='opt'>--address<arg choice='plain'>ADDRESS</arg></arg>
78
<arg choice='opt'>--port<arg choice='plain'>PORT</arg></arg>
79
<arg choice='opt'>--priority<arg choice='plain'>PRIORITY</arg></arg>
80
<arg choice='opt'>--servicename<arg choice='plain'>NAME</arg></arg>
81
<arg choice='opt'>--configdir<arg choice='plain'>DIRECTORY</arg></arg>
82
<arg choice='opt'>--debug</arg>
85
<command>&COMMANDNAME;</command>
86
<arg choice='plain'>--help</arg>
89
<command>&COMMANDNAME;</command>
90
<arg choice='plain'>--check</arg>
93
<command>&COMMANDNAME;</command>
94
<arg choice='plain'>--version</arg>
56
<arg choice="plain"><option>--interface
57
<replaceable>NAME</replaceable></option></arg>
58
<arg choice="plain"><option>-i
59
<replaceable>NAME</replaceable></option></arg>
63
<arg choice="plain"><option>--address
64
<replaceable>ADDRESS</replaceable></option></arg>
65
<arg choice="plain"><option>-a
66
<replaceable>ADDRESS</replaceable></option></arg>
70
<arg choice="plain"><option>--port
71
<replaceable>PORT</replaceable></option></arg>
72
<arg choice="plain"><option>-p
73
<replaceable>PORT</replaceable></option></arg>
76
<arg><option>--priority
77
<replaceable>PRIORITY</replaceable></option></arg>
79
<arg><option>--servicename
80
<replaceable>NAME</replaceable></option></arg>
82
<arg><option>--configdir
83
<replaceable>DIRECTORY</replaceable></option></arg>
85
<arg><option>--debug</option></arg>
88
<command>&COMMANDNAME;</command>
90
<arg choice="plain"><option>--help</option></arg>
91
<arg choice="plain"><option>-h</option></arg>
95
<command>&COMMANDNAME;</command>
96
<arg choice="plain"><option>--version</option></arg>
99
<command>&COMMANDNAME;</command>
100
<arg choice="plain"><option>--check</option></arg>
98
104
<refsect1 id="description">
99
105
<title>DESCRIPTION</title>
101
<command>&COMMANDNAME;</command> is a server daemon that handels
102
incomming passwords request for passwords. Mandos use avahi to
103
announce the service, and through gnutls authenticates
104
clients. Any authenticated client is then given its encrypted
110
<term><literal>-h</literal>, <literal>--help</literal></term>
113
show a help message and exit
119
<term><literal>-i</literal>, <literal>--interface <replaceable>
120
IF</replaceable></literal></term>
129
<term><literal>-a</literal>, <literal>--address <replaceable>
130
ADDRESS</replaceable></literal></term>
133
Address to listen for requests on
139
<term><literal>-p</literal>, <literal>--port <replaceable>
140
PORT</replaceable></literal></term>
143
Port number to receive requests on
149
<term><literal>--check</literal></term>
152
Run self-test on the server
158
<term><literal>--debug</literal></term>
167
<term><literal>--priority <replaceable>
168
PRIORITY</replaceable></literal></term>
171
GnuTLS priority string. See <citerefentry>
172
<refentrytitle>gnutls_priority_init</refentrytitle>
173
<manvolnum>3</manvolnum></citerefentry>
179
<term><literal>--servicename <replaceable>NAME</replaceable>
183
Zeroconf service name
189
<term><literal>--configdir <replaceable>DIR</replaceable>
193
Directory to search for configuration files
107
<command>&COMMANDNAME;</command> is a server daemon which
108
handles incoming request for passwords for a pre-defined list of
109
client host computers. The Mandos server uses Zeroconf to
110
announce itself on the local network, and uses TLS to
111
communicate securely with and to authenticate the clients. The
112
Mandos server uses IPv6 to allow Mandos clients to use IPv6
113
link-local addresses, since the clients will probably not have
114
any other addresses configured (see <xref linkend="overview"/>).
115
Any authenticated client is then given the stored pre-encrypted
116
password for that specific client.
121
<refsect1 id="purpose">
122
<title>PURPOSE</title>
125
The purpose of this is to enable <emphasis>remote and unattended
126
rebooting</emphasis> of client host computer with an
127
<emphasis>encrypted root file system</emphasis>. See <xref
128
linkend="overview"/> for details.
133
<refsect1 id="options">
134
<title>OPTIONS</title>
138
<term><option>--help</option></term>
139
<term><option>-h</option></term>
142
Show a help message and exit
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
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>
216
Directory to search for configuration files. Default is
217
<quote><literal>/etc/mandos</literal></quote>. See
218
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
219
<manvolnum>5</manvolnum></citerefentry> and <citerefentry>
220
<refentrytitle>mandos-clients.conf</refentrytitle>
221
<manvolnum>5</manvolnum></citerefentry>.
227
<term><option>--version</option></term>
230
Prints the program version and exit.
237
<refsect1 id="overview">
238
<title>OVERVIEW</title>
239
<xi:include href="overview.xml"/>
241
This program is the server part. It is a normal server program
242
and will run in a normal system environment, not in an initial
243
RAM disk environment.
247
<refsect1 id="protocol">
248
<title>NETWORK PROTOCOL</title>
250
The Mandos server announces itself as a Zeroconf service of type
251
<quote><literal>_mandos._tcp</literal></quote>. The Mandos
252
client connects to the announced address and port, and sends a
253
line of text where the first whitespace-separated field is the
254
protocol version, which currently is
255
<quote><literal>1</literal></quote>. The client and server then
256
start a TLS protocol handshake with a slight quirk: the Mandos
257
server program acts as a TLS <quote>client</quote> while the
258
connecting Mandos client acts as a TLS <quote>server</quote>.
259
The Mandos client must supply an OpenPGP certificate, and the
260
fingerprint of this certificate is used by the Mandos server to
261
look up (in a list read from <filename>clients.conf</filename>
262
at start time) which binary blob to give the client. No other
263
authentication or authorization is done by the server.
266
<title>Mandos Protocol (Version 1)</title><tgroup cols="3"><thead>
268
<entry>Mandos Client</entry>
269
<entry>Direction</entry>
270
<entry>Mandos Server</entry>
274
<entry>Connect</entry>
275
<entry>-><!-- → --></entry>
278
<entry><quote><literal>1\r\n</literal></quote></entry>
279
<entry>-><!-- → --></entry>
282
<entry>TLS handshake <emphasis>as TLS <quote>server</quote>
284
<entry><-><!-- ⟷ --></entry>
285
<entry>TLS handshake <emphasis>as TLS <quote>client</quote>
289
<entry>OpenPGP public key (part of TLS handshake)</entry>
290
<entry>-><!-- → --></entry>
294
<entry><-<!-- ← --></entry>
295
<entry>Binary blob (client will assume OpenPGP data)</entry>
299
<entry><-<!-- ← --></entry>
302
</tbody></tgroup></table>
305
<refsect1 id="checking">
306
<title>CHECKING</title>
308
The server will, by default, continually check that the clients
309
are still up. If a client has not been confirmed as being up
310
for some time, the client is assumed to be compromised and is no
311
longer eligible to receive the encrypted password. The timeout,
312
checker program, and interval between checks can be configured
313
both globally and per client; see <citerefentry>
314
<refentrytitle>mandos-clients.conf</refentrytitle>
315
<manvolnum>5</manvolnum></citerefentry>.
319
<refsect1 id="logging">
320
<title>LOGGING</title>
322
The server will send log message with various severity levels to
323
<filename>/dev/log</filename>. With the
324
<option>--debug</option> option, it will log even more messages,
325
and also show them on the console.
329
<refsect1 id="exit_status">
330
<title>EXIT STATUS</title>
332
The server will exit with a non-zero exit status only when a
333
critical error is encountered.
337
<refsect1 id="environment">
338
<title>ENVIRONMENT</title>
341
<term><envar>PATH</envar></term>
344
To start the configured checker (see <xref
345
linkend="checking"/>), the server uses
346
<filename>/bin/sh</filename>, which in turn uses
347
<varname>PATH</varname> to search for matching commands if
348
an absolute path is not given. See <citerefentry>
349
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
360
Use the <option>--configdir</option> option to change where
361
<command>&COMMANDNAME;</command> looks for its configurations
362
files. The default file names are listed here.
366
<term><filename>/etc/mandos/mandos.conf</filename></term>
369
Server-global settings. See
370
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
371
<manvolnum>5</manvolnum></citerefentry> for details.
376
<term><filename>/etc/mandos/clients.conf</filename></term>
379
List of clients and client-specific settings. See
380
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
381
<manvolnum>5</manvolnum></citerefentry> for details.
386
<term><filename>/var/run/mandos/mandos.pid</filename></term>
389
The file containing the process id of
390
<command>&COMMANDNAME;</command>.
395
<term><filename>/dev/log</filename></term>
398
The Unix domain socket to where local syslog messages are
404
<term><filename>/bin/sh</filename></term>
407
This is used to start the configured checker command for
408
each client. See <citerefentry>
409
<refentrytitle>mandos-clients.conf</refentrytitle>
410
<manvolnum>5</manvolnum></citerefentry> for details.
420
This server might, on especially fatal errors, emit a Python
421
backtrace. This could be considered a feature.
424
Currently, if a client is declared <quote>invalid</quote> due to
425
having timed out, the server does not record this fact onto
426
permanent storage. This has some security implications, see
427
<xref linkend="CLIENTS"/>.
430
There is currently no way of querying the server of the current
431
status of clients, other than analyzing its <systemitem
432
class="service">syslog</systemitem> output.
435
There is no fine-grained control over logging and debug output.
438
Debug mode is conflated with running in the foreground.
441
The console log messages does not show a timestamp.
445
<refsect1 id="example">
446
<title>EXAMPLE</title>
449
Normal invocation needs no options:
452
<userinput>&COMMANDNAME;</userinput>
457
Run the server in debug mode, read configuration files from
458
the <filename>~/mandos</filename> directory, and use the
459
Zeroconf service name <quote>Test</quote> to not collide with
460
any other official Mandos server on this host:
464
<!-- do not wrap this line -->
465
<userinput>&COMMANDNAME; --debug --configdir ~/mandos --servicename Test</userinput>
471
Run the server normally, but only listen to one interface and
472
only on the link-local address on that interface:
476
<!-- do not wrap this line -->
477
<userinput>&COMMANDNAME; --interface eth7 --address fe80::aede:48ff:fe71:f6f2</userinput>
483
<refsect1 id="security">
484
<title>SECURITY</title>
485
<refsect2 id="SERVER">
486
<title>SERVER</title>
488
Running this <command>&COMMANDNAME;</command> server program
489
should not in itself present any security risk to the host
490
computer running it. The program does not need any special
491
privileges to run, and is designed to run as a non-root user.
494
<refsect2 id="CLIENTS">
495
<title>CLIENTS</title>
497
The server only gives out its stored data to clients which
498
does have the OpenPGP key of the stored fingerprint. This is
499
guaranteed by the fact that the client sends its OpenPGP
500
public key in the TLS handshake; this ensures it to be
501
genuine. The server computes the fingerprint of the key
502
itself and looks up the fingerprint in its list of
503
clients. The <filename>clients.conf</filename> file (see
504
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
505
<manvolnum>5</manvolnum></citerefentry>)
506
<emphasis>must</emphasis> be made non-readable by anyone
507
except the user running the server.
510
As detailed in <xref linkend="checking"/>, the status of all
511
client computers will continually be checked and be assumed
512
compromised if they are gone for too long.
515
If a client is compromised, its downtime should be duly noted
516
by the server which would therefore declare the client
517
invalid. But if the server was ever restarted, it would
518
re-read its client list from its configuration file and again
519
regard all clients therein as valid, and hence eligible to
520
receive their passwords. Therefore, be careful when
521
restarting servers if it is suspected that a client has, in
522
fact, been compromised by parties who may now be running a
523
fake Mandos client with the keys from the non-encrypted
524
initial RAM image of the client host. What should be done in
525
that case (if restarting the server program really is
526
necessary) is to stop the server program, edit the
527
configuration file to omit any suspect clients, and restart
531
For more details on client-side security, see
532
<citerefentry><refentrytitle>password-request</refentrytitle>
533
<manvolnum>8mandos</manvolnum></citerefentry>.
538
<refsect1 id="see_also">
539
<title>SEE ALSO</title>
542
<refentrytitle>mandos-clients.conf</refentrytitle>
543
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
544
<refentrytitle>mandos.conf</refentrytitle>
545
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
546
<refentrytitle>password-request</refentrytitle>
547
<manvolnum>8mandos</manvolnum></citerefentry>, <citerefentry>
548
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
554
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
558
Zeroconf is the network protocol standard used by clients
559
for finding this Mandos server on the local network.
565
<ulink url="http://www.avahi.org/">Avahi</ulink>
569
Avahi is the library this server calls to implement
570
Zeroconf service announcements.
576
<ulink url="http://www.gnu.org/software/gnutls/"
581
GnuTLS is the library this server uses to implement TLS for
582
communicating securely with the client, and at the same time
583
confidently get the client’s public OpenPGP key.
589
RFC 4291: <citetitle>IP Version 6 Addressing
590
Architecture</citetitle>
595
<term>Section 2.2: <citetitle>Text Representation of
596
Addresses</citetitle></term>
597
<listitem><para/></listitem>
600
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
601
Address</citetitle></term>
602
<listitem><para/></listitem>
605
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
606
Addresses</citetitle></term>
609
The clients use IPv6 link-local addresses, which are
610
immediately usable since a link-local addresses is
611
automatically assigned to a network interfaces when it
621
RFC 4346: <citetitle>The Transport Layer Security (TLS)
622
Protocol Version 1.1</citetitle>
626
TLS 1.1 is the protocol implemented by GnuTLS.
632
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
636
The data sent to clients is binary encrypted OpenPGP data.
642
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
647
This is implemented by GnuTLS and used by this server so
648
that OpenPGP keys can be used.
655
<!-- Local Variables: -->
656
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657
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658
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