67
48
<refname><command>&COMMANDNAME;</command></refname>
69
Sends encrypted passwords to authenticated mandos clients
50
Gives encrypted passwords to authenticated Mandos clients
75
56
<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>
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-ipv6</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>
98
108
<refsect1 id="description">
99
109
<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
111
<command>&COMMANDNAME;</command> is a server daemon which
112
handles incoming request for passwords for a pre-defined list of
113
client host computers. The Mandos server uses Zeroconf to
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.
124
<refsect1 id="purpose">
125
<title>PURPOSE</title>
127
The purpose of this is to enable <emphasis>remote and unattended
128
rebooting</emphasis> of client host computer with an
129
<emphasis>encrypted root file system</emphasis>. See <xref
130
linkend="overview"/> for details.
134
<refsect1 id="options">
135
<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.
236
<term><option>--no-ipv6</option></term>
238
<xi:include href="mandos-options.xml" xpointer="ipv6"/>
244
<refsect1 id="overview">
245
<title>OVERVIEW</title>
246
<xi:include href="overview.xml"/>
248
This program is the server part. It is a normal server program
249
and will run in a normal system environment, not in an initial
250
<acronym>RAM</acronym> disk environment.
254
<refsect1 id="protocol">
255
<title>NETWORK PROTOCOL</title>
257
The Mandos server announces itself as a Zeroconf service of type
258
<quote><literal>_mandos._tcp</literal></quote>. The Mandos
259
client connects to the announced address and port, and sends a
260
line of text where the first whitespace-separated field is the
261
protocol version, which currently is
262
<quote><literal>1</literal></quote>. The client and server then
263
start a TLS protocol handshake with a slight quirk: the Mandos
264
server program acts as a TLS <quote>client</quote> while the
265
connecting Mandos client acts as a TLS <quote>server</quote>.
266
The Mandos client must supply an OpenPGP certificate, and the
267
fingerprint of this certificate is used by the Mandos server to
268
look up (in a list read from <filename>clients.conf</filename>
269
at start time) which binary blob to give the client. No other
270
authentication or authorization is done by the server.
273
<title>Mandos Protocol (Version 1)</title><tgroup cols="3"><thead>
275
<entry>Mandos Client</entry>
276
<entry>Direction</entry>
277
<entry>Mandos Server</entry>
281
<entry>Connect</entry>
282
<entry>-><!-- → --></entry>
285
<entry><quote><literal>1\r\n</literal></quote></entry>
286
<entry>-><!-- → --></entry>
289
<entry>TLS handshake <emphasis>as TLS <quote>server</quote>
291
<entry><-><!-- ⟷ --></entry>
292
<entry>TLS handshake <emphasis>as TLS <quote>client</quote>
296
<entry>OpenPGP public key (part of TLS handshake)</entry>
297
<entry>-><!-- → --></entry>
301
<entry><-<!-- ← --></entry>
302
<entry>Binary blob (client will assume OpenPGP data)</entry>
306
<entry><-<!-- ← --></entry>
309
</tbody></tgroup></table>
312
<refsect1 id="checking">
313
<title>CHECKING</title>
315
The server will, by default, continually check that the clients
316
are still up. If a client has not been confirmed as being up
317
for some time, the client is assumed to be compromised and is no
318
longer eligible to receive the encrypted password. The timeout,
319
checker program, and interval between checks can be configured
320
both globally and per client; see <citerefentry>
321
<refentrytitle>mandos-clients.conf</refentrytitle>
322
<manvolnum>5</manvolnum></citerefentry>.
326
<refsect1 id="logging">
327
<title>LOGGING</title>
329
The server will send log message with various severity levels to
330
<filename>/dev/log</filename>. With the
331
<option>--debug</option> option, it will log even more messages,
332
and also show them on the console.
336
<refsect1 id="exit_status">
337
<title>EXIT STATUS</title>
339
The server will exit with a non-zero exit status only when a
340
critical error is encountered.
344
<refsect1 id="environment">
345
<title>ENVIRONMENT</title>
348
<term><envar>PATH</envar></term>
351
To start the configured checker (see <xref
352
linkend="checking"/>), the server uses
353
<filename>/bin/sh</filename>, which in turn uses
354
<varname>PATH</varname> to search for matching commands if
355
an absolute path is not given. See <citerefentry>
356
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
364
<refsect1 id="files">
367
Use the <option>--configdir</option> option to change where
368
<command>&COMMANDNAME;</command> looks for its configurations
369
files. The default file names are listed here.
373
<term><filename>/etc/mandos/mandos.conf</filename></term>
376
Server-global settings. See
377
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
378
<manvolnum>5</manvolnum></citerefentry> for details.
383
<term><filename>/etc/mandos/clients.conf</filename></term>
386
List of clients and client-specific settings. See
387
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
388
<manvolnum>5</manvolnum></citerefentry> for details.
393
<term><filename>/var/run/mandos.pid</filename></term>
396
The file containing the process id of
397
<command>&COMMANDNAME;</command>.
402
<term><filename>/dev/log</filename></term>
405
The Unix domain socket to where local syslog messages are
411
<term><filename>/bin/sh</filename></term>
414
This is used to start the configured checker command for
415
each client. See <citerefentry>
416
<refentrytitle>mandos-clients.conf</refentrytitle>
417
<manvolnum>5</manvolnum></citerefentry> for details.
427
This server might, on especially fatal errors, emit a Python
428
backtrace. This could be considered a feature.
431
Currently, if a client is declared <quote>invalid</quote> due to
432
having timed out, the server does not record this fact onto
433
permanent storage. This has some security implications, see
434
<xref linkend="clients"/>.
437
There is currently no way of querying the server of the current
438
status of clients, other than analyzing its <systemitem
439
class="service">syslog</systemitem> output.
442
There is no fine-grained control over logging and debug output.
445
Debug mode is conflated with running in the foreground.
448
The console log messages do not show a time stamp.
451
This server does not check the expire time of clients’ OpenPGP
456
<refsect1 id="example">
457
<title>EXAMPLE</title>
460
Normal invocation needs no options:
463
<userinput>&COMMANDNAME;</userinput>
468
Run the server in debug mode, read configuration files from
469
the <filename>~/mandos</filename> directory, and use the
470
Zeroconf service name <quote>Test</quote> to not collide with
471
any other official Mandos server on this host:
475
<!-- do not wrap this line -->
476
<userinput>&COMMANDNAME; --debug --configdir ~/mandos --servicename Test</userinput>
482
Run the server normally, but only listen to one interface and
483
only on the link-local address on that interface:
487
<!-- do not wrap this line -->
488
<userinput>&COMMANDNAME; --interface eth7 --address fe80::aede:48ff:fe71:f6f2</userinput>
494
<refsect1 id="security">
495
<title>SECURITY</title>
496
<refsect2 id="server">
497
<title>SERVER</title>
499
Running this <command>&COMMANDNAME;</command> server program
500
should not in itself present any security risk to the host
501
computer running it. The program switches to a non-root user
505
<refsect2 id="clients">
506
<title>CLIENTS</title>
508
The server only gives out its stored data to clients which
509
does have the OpenPGP key of the stored fingerprint. This is
510
guaranteed by the fact that the client sends its OpenPGP
511
public key in the TLS handshake; this ensures it to be
512
genuine. The server computes the fingerprint of the key
513
itself and looks up the fingerprint in its list of
514
clients. The <filename>clients.conf</filename> file (see
515
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
516
<manvolnum>5</manvolnum></citerefentry>)
517
<emphasis>must</emphasis> be made non-readable by anyone
518
except the user starting the server (usually root).
521
As detailed in <xref linkend="checking"/>, the status of all
522
client computers will continually be checked and be assumed
523
compromised if they are gone for too long.
526
If a client is compromised, its downtime should be duly noted
527
by the server which would therefore declare the client
528
invalid. But if the server was ever restarted, it would
529
re-read its client list from its configuration file and again
530
regard all clients therein as valid, and hence eligible to
531
receive their passwords. Therefore, be careful when
532
restarting servers if it is suspected that a client has, in
533
fact, been compromised by parties who may now be running a
534
fake Mandos client with the keys from the non-encrypted
535
initial <acronym>RAM</acronym> image of the client host. What
536
should be done in that case (if restarting the server program
537
really is necessary) is to stop the server program, edit the
538
configuration file to omit any suspect clients, and restart
542
For more details on client-side security, see
543
<citerefentry><refentrytitle>mandos-client</refentrytitle>
544
<manvolnum>8mandos</manvolnum></citerefentry>.
549
<refsect1 id="see_also">
550
<title>SEE ALSO</title>
553
<refentrytitle>mandos-clients.conf</refentrytitle>
554
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
555
<refentrytitle>mandos.conf</refentrytitle>
556
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
557
<refentrytitle>mandos-client</refentrytitle>
558
<manvolnum>8mandos</manvolnum></citerefentry>, <citerefentry>
559
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
565
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
569
Zeroconf is the network protocol standard used by clients
570
for finding this Mandos server on the local network.
576
<ulink url="http://www.avahi.org/">Avahi</ulink>
580
Avahi is the library this server calls to implement
581
Zeroconf service announcements.
587
<ulink url="http://www.gnu.org/software/gnutls/"
592
GnuTLS is the library this server uses to implement TLS for
593
communicating securely with the client, and at the same time
594
confidently get the client’s public OpenPGP key.
600
RFC 4291: <citetitle>IP Version 6 Addressing
601
Architecture</citetitle>
606
<term>Section 2.2: <citetitle>Text Representation of
607
Addresses</citetitle></term>
608
<listitem><para/></listitem>
611
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
612
Address</citetitle></term>
613
<listitem><para/></listitem>
616
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
617
Addresses</citetitle></term>
620
The clients use IPv6 link-local addresses, which are
621
immediately usable since a link-local addresses is
622
automatically assigned to a network interfaces when it
632
RFC 4346: <citetitle>The Transport Layer Security (TLS)
633
Protocol Version 1.1</citetitle>
637
TLS 1.1 is the protocol implemented by GnuTLS.
643
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
647
The data sent to clients is binary encrypted OpenPGP data.
653
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
658
This is implemented by GnuTLS and used by this server so
659
that OpenPGP keys can be used.
666
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