67
47
<refname><command>&COMMANDNAME;</command></refname>
69
Sends encrypted passwords to authenticated mandos clients
49
Gives encrypted passwords to authenticated Mandos clients
75
55
<command>&COMMANDNAME;</command>
76
<arg choice='opt' rep='repeat'>OPTION</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>
88
<arg><option>--no-dbus</option></arg>
91
<command>&COMMANDNAME;</command>
93
<arg choice="plain"><option>--help</option></arg>
94
<arg choice="plain"><option>-h</option></arg>
98
<command>&COMMANDNAME;</command>
99
<arg choice="plain"><option>--version</option></arg>
102
<command>&COMMANDNAME;</command>
103
<arg choice="plain"><option>--check</option></arg>
80
107
<refsect1 id="description">
81
108
<title>DESCRIPTION</title>
83
<command>&COMMANDNAME;</command> is a server daemon that handels
84
incomming passwords request for passwords. Mandos use avahi to
85
announce the service, and through gnutls authenticates
86
clients. Any authenticated client is then given its encrypted
92
<term><literal>-h</literal>, <literal>--help</literal></term>
95
show a help message and exit
101
<term><literal>-i</literal>, <literal>--interface <replaceable>
102
IF</replaceable></literal></term>
111
<term><literal>-a</literal>, <literal>--address <replaceable>
112
ADDRESS</replaceable></literal></term>
115
Address to listen for requests on
121
<term><literal>-p</literal>, <literal>--port <replaceable>
122
PORT</replaceable></literal></term>
125
Port number to receive requests on
131
<term><literal>--check</literal></term>
134
Run self-test on the server
140
<term><literal>--debug</literal></term>
149
<term><literal>--priority <replaceable>
150
PRIORITY</replaceable></literal></term>
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GnuTLS priority string. See <citerefentry>
154
<refentrytitle>gnutls_priority_init</refentrytitle>
155
<manvolnum>3</manvolnum></citerefentry>
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<term><literal>--servicename <replaceable>NAME</replaceable>
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Zeroconf service name
171
<term><literal>--configdir <replaceable>DIR</replaceable>
175
Directory to search for configuration files
110
<command>&COMMANDNAME;</command> is a server daemon which
111
handles incoming request for passwords for a pre-defined list of
112
client host computers. The Mandos server uses Zeroconf to
113
announce itself on the local network, and uses TLS to
114
communicate securely with and to authenticate the clients. The
115
Mandos server uses IPv6 to allow Mandos clients to use IPv6
116
link-local addresses, since the clients will probably not have
117
any other addresses configured (see <xref linkend="overview"/>).
118
Any authenticated client is then given the stored pre-encrypted
119
password for that specific client.
123
<refsect1 id="purpose">
124
<title>PURPOSE</title>
126
The purpose of this is to enable <emphasis>remote and unattended
127
rebooting</emphasis> of client host computer with an
128
<emphasis>encrypted root file system</emphasis>. See <xref
129
linkend="overview"/> for details.
133
<refsect1 id="options">
134
<title>OPTIONS</title>
137
<term><option>--help</option></term>
138
<term><option>-h</option></term>
141
Show a help message and exit
147
<term><option>--interface</option>
148
<replaceable>NAME</replaceable></term>
149
<term><option>-i</option>
150
<replaceable>NAME</replaceable></term>
152
<xi:include href="mandos-options.xml" xpointer="interface"/>
157
<term><option>--address
158
<replaceable>ADDRESS</replaceable></option></term>
160
<replaceable>ADDRESS</replaceable></option></term>
162
<xi:include href="mandos-options.xml" xpointer="address"/>
168
<replaceable>PORT</replaceable></option></term>
170
<replaceable>PORT</replaceable></option></term>
172
<xi:include href="mandos-options.xml" xpointer="port"/>
177
<term><option>--check</option></term>
180
Run the server’s self-tests. This includes any unit
187
<term><option>--debug</option></term>
189
<xi:include href="mandos-options.xml" xpointer="debug"/>
194
<term><option>--priority <replaceable>
195
PRIORITY</replaceable></option></term>
197
<xi:include href="mandos-options.xml" xpointer="priority"/>
202
<term><option>--servicename
203
<replaceable>NAME</replaceable></option></term>
205
<xi:include href="mandos-options.xml"
206
xpointer="servicename"/>
211
<term><option>--configdir
212
<replaceable>DIRECTORY</replaceable></option></term>
215
Directory to search for configuration files. Default is
216
<quote><literal>/etc/mandos</literal></quote>. See
217
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
218
<manvolnum>5</manvolnum></citerefentry> and <citerefentry>
219
<refentrytitle>mandos-clients.conf</refentrytitle>
220
<manvolnum>5</manvolnum></citerefentry>.
226
<term><option>--version</option></term>
229
Prints the program version and exit.
235
<term><option>--no-dbus</option></term>
237
<xi:include href="mandos-options.xml" xpointer="dbus"/>
239
See also <xref linkend="dbus"/>.
245
<refsect1 id="overview">
246
<title>OVERVIEW</title>
247
<xi:include href="overview.xml"/>
249
This program is the server part. It is a normal server program
250
and will run in a normal system environment, not in an initial
251
<acronym>RAM</acronym> disk environment.
255
<refsect1 id="protocol">
256
<title>NETWORK PROTOCOL</title>
258
The Mandos server announces itself as a Zeroconf service of type
259
<quote><literal>_mandos._tcp</literal></quote>. The Mandos
260
client connects to the announced address and port, and sends a
261
line of text where the first whitespace-separated field is the
262
protocol version, which currently is
263
<quote><literal>1</literal></quote>. The client and server then
264
start a TLS protocol handshake with a slight quirk: the Mandos
265
server program acts as a TLS <quote>client</quote> while the
266
connecting Mandos client acts as a TLS <quote>server</quote>.
267
The Mandos client must supply an OpenPGP certificate, and the
268
fingerprint of this certificate is used by the Mandos server to
269
look up (in a list read from <filename>clients.conf</filename>
270
at start time) which binary blob to give the client. No other
271
authentication or authorization is done by the server.
274
<title>Mandos Protocol (Version 1)</title><tgroup cols="3"><thead>
276
<entry>Mandos Client</entry>
277
<entry>Direction</entry>
278
<entry>Mandos Server</entry>
282
<entry>Connect</entry>
283
<entry>-><!-- → --></entry>
286
<entry><quote><literal>1\r\n</literal></quote></entry>
287
<entry>-><!-- → --></entry>
290
<entry>TLS handshake <emphasis>as TLS <quote>server</quote>
292
<entry><-><!-- ⟷ --></entry>
293
<entry>TLS handshake <emphasis>as TLS <quote>client</quote>
297
<entry>OpenPGP public key (part of TLS handshake)</entry>
298
<entry>-><!-- → --></entry>
302
<entry><-<!-- ← --></entry>
303
<entry>Binary blob (client will assume OpenPGP data)</entry>
307
<entry><-<!-- ← --></entry>
310
</tbody></tgroup></table>
313
<refsect1 id="checking">
314
<title>CHECKING</title>
316
The server will, by default, continually check that the clients
317
are still up. If a client has not been confirmed as being up
318
for some time, the client is assumed to be compromised and is no
319
longer eligible to receive the encrypted password. The timeout,
320
checker program, and interval between checks can be configured
321
both globally and per client; see <citerefentry>
322
<refentrytitle>mandos-clients.conf</refentrytitle>
323
<manvolnum>5</manvolnum></citerefentry>.
327
<refsect1 id="logging">
328
<title>LOGGING</title>
330
The server will send log message with various severity levels to
331
<filename>/dev/log</filename>. With the
332
<option>--debug</option> option, it will log even more messages,
333
and also show them on the console.
338
<title>D-BUS INTERFACE</title>
340
The server will by default provide a D-Bus system bus interface.
341
This interface will only be accessible by the root user or a
342
Mandos-specific user, if such a user exists.
347
<refsect1 id="exit_status">
348
<title>EXIT STATUS</title>
350
The server will exit with a non-zero exit status only when a
351
critical error is encountered.
355
<refsect1 id="environment">
356
<title>ENVIRONMENT</title>
359
<term><envar>PATH</envar></term>
362
To start the configured checker (see <xref
363
linkend="checking"/>), the server uses
364
<filename>/bin/sh</filename>, which in turn uses
365
<varname>PATH</varname> to search for matching commands if
366
an absolute path is not given. See <citerefentry>
367
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
375
<refsect1 id="files">
378
Use the <option>--configdir</option> option to change where
379
<command>&COMMANDNAME;</command> looks for its configurations
380
files. The default file names are listed here.
384
<term><filename>/etc/mandos/mandos.conf</filename></term>
387
Server-global settings. See
388
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
389
<manvolnum>5</manvolnum></citerefentry> for details.
394
<term><filename>/etc/mandos/clients.conf</filename></term>
397
List of clients and client-specific settings. See
398
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
399
<manvolnum>5</manvolnum></citerefentry> for details.
404
<term><filename>/var/run/mandos.pid</filename></term>
407
The file containing the process id of
408
<command>&COMMANDNAME;</command>.
413
<term><filename>/dev/log</filename></term>
416
The Unix domain socket to where local syslog messages are
422
<term><filename>/bin/sh</filename></term>
425
This is used to start the configured checker command for
426
each client. See <citerefentry>
427
<refentrytitle>mandos-clients.conf</refentrytitle>
428
<manvolnum>5</manvolnum></citerefentry> for details.
438
This server might, on especially fatal errors, emit a Python
439
backtrace. This could be considered a feature.
442
Currently, if a client is declared <quote>invalid</quote> due to
443
having timed out, the server does not record this fact onto
444
permanent storage. This has some security implications, see
445
<xref linkend="clients"/>.
448
There is currently no way of querying the server of the current
449
status of clients, other than analyzing its <systemitem
450
class="service">syslog</systemitem> output.
453
There is no fine-grained control over logging and debug output.
456
Debug mode is conflated with running in the foreground.
459
The console log messages does not show a time stamp.
462
This server does not check the expire time of clients’ OpenPGP
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 switches to 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 starting the server (usually root).
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 <acronym>RAM</acronym> image of the client host. What
547
should be done in that case (if restarting the server program
548
really is 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>mandos-client</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>mandos-client</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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