67
68
<refname><command>&COMMANDNAME;</command></refname>
69
Sends encrypted passwords to authenticated mandos clients
70
Gives encrypted passwords to authenticated Mandos clients
75
76
<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'>--version</arg>
93
<command>&COMMANDNAME;</command>
94
<arg choice='plain'>--check</arg>
78
<arg choice="plain"><option>--interface
79
<replaceable>NAME</replaceable></option></arg>
80
<arg choice="plain"><option>-i
81
<replaceable>NAME</replaceable></option></arg>
85
<arg choice="plain"><option>--address
86
<replaceable>ADDRESS</replaceable></option></arg>
87
<arg choice="plain"><option>-a
88
<replaceable>ADDRESS</replaceable></option></arg>
92
<arg choice="plain"><option>--port
93
<replaceable>PORT</replaceable></option></arg>
94
<arg choice="plain"><option>-p
95
<replaceable>PORT</replaceable></option></arg>
98
<arg><option>--priority
99
<replaceable>PRIORITY</replaceable></option></arg>
101
<arg><option>--servicename
102
<replaceable>NAME</replaceable></option></arg>
104
<arg><option>--configdir
105
<replaceable>DIRECTORY</replaceable></option></arg>
107
<arg><option>--debug</option></arg>
110
<command>&COMMANDNAME;</command>
112
<arg choice="plain"><option>--help</option></arg>
113
<arg choice="plain"><option>-h</option></arg>
117
<command>&COMMANDNAME;</command>
118
<arg choice="plain"><option>--version</option></arg>
121
<command>&COMMANDNAME;</command>
122
<arg choice="plain"><option>--check</option></arg>
98
126
<refsect1 id="description">
99
127
<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
199
<term><literal>--version</literal></term>
202
Prints the program version
129
<command>&COMMANDNAME;</command> is a server daemon which
130
handles incoming request for passwords for a pre-defined list of
131
client host computers. The Mandos server uses Zeroconf to
132
announce itself on the local network, and uses TLS to
133
communicate securely with and to authenticate the clients. The
134
Mandos server uses IPv6 to allow Mandos clients to use IPv6
135
link-local addresses, since the clients will probably not have
136
any other addresses configured (see <xref linkend="overview"/>).
137
Any authenticated client is then given the stored pre-encrypted
138
password for that specific client.
143
<refsect1 id="purpose">
144
<title>PURPOSE</title>
147
The purpose of this is to enable <emphasis>remote and unattended
148
rebooting</emphasis> of client host computer with an
149
<emphasis>encrypted root file system</emphasis>. See <xref
150
linkend="overview"/> for details.
155
<refsect1 id="options">
156
<title>OPTIONS</title>
160
<term><option>--help</option></term>
161
<term><option>-h</option></term>
164
Show a help message and exit
170
<term><option>--interface</option>
171
<replaceable>NAME</replaceable></term>
172
<term><option>-i</option>
173
<replaceable>NAME</replaceable></term>
175
<xi:include href="mandos-options.xml" xpointer="interface"/>
180
<term><option>--address
181
<replaceable>ADDRESS</replaceable></option></term>
183
<replaceable>ADDRESS</replaceable></option></term>
185
<xi:include href="mandos-options.xml" xpointer="address"/>
191
<replaceable>PORT</replaceable></option></term>
193
<replaceable>PORT</replaceable></option></term>
195
<xi:include href="mandos-options.xml" xpointer="port"/>
200
<term><option>--check</option></term>
203
Run the server’s self-tests. This includes any unit
210
<term><option>--debug</option></term>
212
<xi:include href="mandos-options.xml" xpointer="debug"/>
217
<term><option>--priority <replaceable>
218
PRIORITY</replaceable></option></term>
220
<xi:include href="mandos-options.xml" xpointer="priority"/>
225
<term><option>--servicename
226
<replaceable>NAME</replaceable></option></term>
228
<xi:include href="mandos-options.xml"
229
xpointer="servicename"/>
234
<term><option>--configdir
235
<replaceable>DIRECTORY</replaceable></option></term>
238
Directory to search for configuration files. Default is
239
<quote><literal>/etc/mandos</literal></quote>. See
240
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
241
<manvolnum>5</manvolnum></citerefentry> and <citerefentry>
242
<refentrytitle>mandos-clients.conf</refentrytitle>
243
<manvolnum>5</manvolnum></citerefentry>.
249
<term><option>--version</option></term>
252
Prints the program version and exit.
259
<refsect1 id="overview">
260
<title>OVERVIEW</title>
261
<xi:include href="overview.xml"/>
263
This program is the server part. It is a normal server program
264
and will run in a normal system environment, not in an initial
265
RAM disk environment.
269
<refsect1 id="protocol">
270
<title>NETWORK PROTOCOL</title>
272
The Mandos server announces itself as a Zeroconf service of type
273
<quote><literal>_mandos._tcp</literal></quote>. The Mandos
274
client connects to the announced address and port, and sends a
275
line of text where the first whitespace-separated field is the
276
protocol version, which currently is
277
<quote><literal>1</literal></quote>. The client and server then
278
start a TLS protocol handshake with a slight quirk: the Mandos
279
server program acts as a TLS <quote>client</quote> while the
280
connecting Mandos client acts as a TLS <quote>server</quote>.
281
The Mandos client must supply an OpenPGP certificate, and the
282
fingerprint of this certificate is used by the Mandos server to
283
look up (in a list read from <filename>clients.conf</filename>
284
at start time) which binary blob to give the client. No other
285
authentication or authorization is done by the server.
288
<title>Mandos Protocol (Version 1)</title><tgroup cols="3"><thead>
290
<entry>Mandos Client</entry>
291
<entry>Direction</entry>
292
<entry>Mandos Server</entry>
296
<entry>Connect</entry>
297
<entry>-><!-- → --></entry>
300
<entry><quote><literal>1\r\n</literal></quote></entry>
301
<entry>-><!-- → --></entry>
304
<entry>TLS handshake <emphasis>as TLS <quote>server</quote>
306
<entry><-><!-- ⟷ --></entry>
307
<entry>TLS handshake <emphasis>as TLS <quote>client</quote>
311
<entry>OpenPGP public key (part of TLS handshake)</entry>
312
<entry>-><!-- → --></entry>
316
<entry><-<!-- ← --></entry>
317
<entry>Binary blob (client will assume OpenPGP data)</entry>
321
<entry><-<!-- ← --></entry>
324
</tbody></tgroup></table>
327
<refsect1 id="checking">
328
<title>CHECKING</title>
330
The server will, by default, continually check that the clients
331
are still up. If a client has not been confirmed as being up
332
for some time, the client is assumed to be compromised and is no
333
longer eligible to receive the encrypted password. The timeout,
334
checker program, and interval between checks can be configured
335
both globally and per client; see <citerefentry>
336
<refentrytitle>mandos-clients.conf</refentrytitle>
337
<manvolnum>5</manvolnum></citerefentry>.
341
<refsect1 id="logging">
342
<title>LOGGING</title>
344
The server will send log message with various severity levels to
345
<filename>/dev/log</filename>. With the
346
<option>--debug</option> option, it will log even more messages,
347
and also show them on the console.
351
<refsect1 id="exit_status">
352
<title>EXIT STATUS</title>
354
The server will exit with a non-zero exit status only when a
355
critical error is encountered.
359
<refsect1 id="environment">
360
<title>ENVIRONMENT</title>
363
<term><envar>PATH</envar></term>
366
To start the configured checker (see <xref
367
linkend="checking"/>), the server uses
368
<filename>/bin/sh</filename>, which in turn uses
369
<varname>PATH</varname> to search for matching commands if
370
an absolute path is not given. See <citerefentry>
371
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
382
Use the <option>--configdir</option> option to change where
383
<command>&COMMANDNAME;</command> looks for its configurations
384
files. The default file names are listed here.
388
<term><filename>/etc/mandos/mandos.conf</filename></term>
391
Server-global settings. See
392
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
393
<manvolnum>5</manvolnum></citerefentry> for details.
398
<term><filename>/etc/mandos/clients.conf</filename></term>
401
List of clients and client-specific settings. See
402
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
403
<manvolnum>5</manvolnum></citerefentry> for details.
408
<term><filename>/var/run/mandos/mandos.pid</filename></term>
411
The file containing the process id of
412
<command>&COMMANDNAME;</command>.
417
<term><filename>/dev/log</filename></term>
420
The Unix domain socket to where local syslog messages are
426
<term><filename>/bin/sh</filename></term>
429
This is used to start the configured checker command for
430
each client. See <citerefentry>
431
<refentrytitle>mandos-clients.conf</refentrytitle>
432
<manvolnum>5</manvolnum></citerefentry> for details.
442
This server might, on especially fatal errors, emit a Python
443
backtrace. This could be considered a feature.
446
Currently, if a client is declared <quote>invalid</quote> due to
447
having timed out, the server does not record this fact onto
448
permanent storage. This has some security implications, see
449
<xref linkend="CLIENTS"/>.
452
There is currently no way of querying the server of the current
453
status of clients, other than analyzing its <systemitem
454
class="service">syslog</systemitem> output.
457
There is no fine-grained control over logging and debug output.
460
Debug mode is conflated with running in the foreground.
463
The console log messages does not show a timestamp.
467
<refsect1 id="example">
468
<title>EXAMPLE</title>
471
Normal invocation needs no options:
474
<userinput>&COMMANDNAME;</userinput>
479
Run the server in debug mode, read configuration files from
480
the <filename>~/mandos</filename> directory, and use the
481
Zeroconf service name <quote>Test</quote> to not collide with
482
any other official Mandos server on this host:
486
<!-- do not wrap this line -->
487
<userinput>&COMMANDNAME; --debug --configdir ~/mandos --servicename Test</userinput>
493
Run the server normally, but only listen to one interface and
494
only on the link-local address on that interface:
498
<!-- do not wrap this line -->
499
<userinput>&COMMANDNAME; --interface eth7 --address fe80::aede:48ff:fe71:f6f2</userinput>
505
<refsect1 id="security">
506
<title>SECURITY</title>
507
<refsect2 id="SERVER">
508
<title>SERVER</title>
510
Running this <command>&COMMANDNAME;</command> server program
511
should not in itself present any security risk to the host
512
computer running it. The program does not need any special
513
privileges to run, and is designed to run as a non-root user.
516
<refsect2 id="CLIENTS">
517
<title>CLIENTS</title>
519
The server only gives out its stored data to clients which
520
does have the OpenPGP key of the stored fingerprint. This is
521
guaranteed by the fact that the client sends its OpenPGP
522
public key in the TLS handshake; this ensures it to be
523
genuine. The server computes the fingerprint of the key
524
itself and looks up the fingerprint in its list of
525
clients. The <filename>clients.conf</filename> file (see
526
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
527
<manvolnum>5</manvolnum></citerefentry>)
528
<emphasis>must</emphasis> be made non-readable by anyone
529
except the user running the server.
532
As detailed in <xref linkend="checking"/>, the status of all
533
client computers will continually be checked and be assumed
534
compromised if they are gone for too long.
537
If a client is compromised, its downtime should be duly noted
538
by the server which would therefore declare the client
539
invalid. But if the server was ever restarted, it would
540
re-read its client list from its configuration file and again
541
regard all clients therein as valid, and hence eligible to
542
receive their passwords. Therefore, be careful when
543
restarting servers if it is suspected that a client has, in
544
fact, been compromised by parties who may now be running a
545
fake Mandos client with the keys from the non-encrypted
546
initial RAM image of the client host. What should be done in
547
that case (if restarting the server program really is
548
necessary) is to stop the server program, edit the
549
configuration file to omit any suspect clients, and restart
553
For more details on client-side security, see
554
<citerefentry><refentrytitle>password-request</refentrytitle>
555
<manvolnum>8mandos</manvolnum></citerefentry>.
560
<refsect1 id="see_also">
561
<title>SEE ALSO</title>
564
<refentrytitle>mandos-clients.conf</refentrytitle>
565
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
566
<refentrytitle>mandos.conf</refentrytitle>
567
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
568
<refentrytitle>password-request</refentrytitle>
569
<manvolnum>8mandos</manvolnum></citerefentry>, <citerefentry>
570
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
576
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
580
Zeroconf is the network protocol standard used by clients
581
for finding this Mandos server on the local network.
587
<ulink url="http://www.avahi.org/">Avahi</ulink>
591
Avahi is the library this server calls to implement
592
Zeroconf service announcements.
598
<ulink url="http://www.gnu.org/software/gnutls/"
603
GnuTLS is the library this server uses to implement TLS for
604
communicating securely with the client, and at the same time
605
confidently get the client’s public OpenPGP key.
611
RFC 4291: <citetitle>IP Version 6 Addressing
612
Architecture</citetitle>
617
<term>Section 2.2: <citetitle>Text Representation of
618
Addresses</citetitle></term>
619
<listitem><para/></listitem>
622
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
623
Address</citetitle></term>
624
<listitem><para/></listitem>
627
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
628
Addresses</citetitle></term>
631
The clients use IPv6 link-local addresses, which are
632
immediately usable since a link-local addresses is
633
automatically assigned to a network interfaces when it
643
RFC 4346: <citetitle>The Transport Layer Security (TLS)
644
Protocol Version 1.1</citetitle>
648
TLS 1.1 is the protocol implemented by GnuTLS.
654
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
658
The data sent to clients is binary encrypted OpenPGP data.
664
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
669
This is implemented by GnuTLS and used by this server so
670
that OpenPGP keys can be used.
677
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678
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679
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