67
50
<refname><command>&COMMANDNAME;</command></refname>
69
Sends encrypted passwords to authenticated mandos clients
52
Gives encrypted passwords to authenticated Mandos clients
75
58
<command>&COMMANDNAME;</command>
76
<arg choice='opt' rep='repeat'>OPTION</arg>
60
<arg choice="plain"><option>--interface
61
<replaceable>NAME</replaceable></option></arg>
62
<arg choice="plain"><option>-i
63
<replaceable>NAME</replaceable></option></arg>
67
<arg choice="plain"><option>--address
68
<replaceable>ADDRESS</replaceable></option></arg>
69
<arg choice="plain"><option>-a
70
<replaceable>ADDRESS</replaceable></option></arg>
74
<arg choice="plain"><option>--port
75
<replaceable>PORT</replaceable></option></arg>
76
<arg choice="plain"><option>-p
77
<replaceable>PORT</replaceable></option></arg>
80
<arg><option>--priority
81
<replaceable>PRIORITY</replaceable></option></arg>
83
<arg><option>--servicename
84
<replaceable>NAME</replaceable></option></arg>
86
<arg><option>--configdir
87
<replaceable>DIRECTORY</replaceable></option></arg>
89
<arg><option>--debug</option></arg>
91
<arg><option>--debuglevel
92
<replaceable>LEVEL</replaceable></option></arg>
94
<arg><option>--no-dbus</option></arg>
96
<arg><option>--no-ipv6</option></arg>
98
<arg><option>--no-restore</option></arg>
101
<command>&COMMANDNAME;</command>
103
<arg choice="plain"><option>--help</option></arg>
104
<arg choice="plain"><option>-h</option></arg>
108
<command>&COMMANDNAME;</command>
109
<arg choice="plain"><option>--version</option></arg>
112
<command>&COMMANDNAME;</command>
113
<arg choice="plain"><option>--check</option></arg>
80
117
<refsect1 id="description">
81
118
<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>
153
GnuTLS priority string. See <citerefentry>
154
<refentrytitle>gnutls_priority_init</refentrytitle>
155
<manvolnum>3</manvolnum></citerefentry>
161
<term><literal>--servicename <replaceable>NAME</replaceable>
165
Zeroconf service name
171
<term><literal>--configdir <replaceable>DIR</replaceable>
175
Directory to search for configuration files
120
<command>&COMMANDNAME;</command> is a server daemon which
121
handles incoming request for passwords for a pre-defined list of
122
client host computers. For an introduction, see
123
<citerefentry><refentrytitle>intro</refentrytitle>
124
<manvolnum>8mandos</manvolnum></citerefentry>. The Mandos server
125
uses Zeroconf to announce itself on the local network, and uses
126
TLS to communicate securely with and to authenticate the
127
clients. The Mandos server uses IPv6 to allow Mandos clients to
128
use IPv6 link-local addresses, since the clients will probably
129
not have any other addresses configured (see <xref
130
linkend="overview"/>). Any authenticated client is then given
131
the stored pre-encrypted password for that specific client.
135
<refsect1 id="purpose">
136
<title>PURPOSE</title>
138
The purpose of this is to enable <emphasis>remote and unattended
139
rebooting</emphasis> of client host computer with an
140
<emphasis>encrypted root file system</emphasis>. See <xref
141
linkend="overview"/> for details.
145
<refsect1 id="options">
146
<title>OPTIONS</title>
149
<term><option>--help</option></term>
150
<term><option>-h</option></term>
153
Show a help message and exit
159
<term><option>--interface</option>
160
<replaceable>NAME</replaceable></term>
161
<term><option>-i</option>
162
<replaceable>NAME</replaceable></term>
164
<xi:include href="mandos-options.xml" xpointer="interface"/>
169
<term><option>--address
170
<replaceable>ADDRESS</replaceable></option></term>
172
<replaceable>ADDRESS</replaceable></option></term>
174
<xi:include href="mandos-options.xml" xpointer="address"/>
180
<replaceable>PORT</replaceable></option></term>
182
<replaceable>PORT</replaceable></option></term>
184
<xi:include href="mandos-options.xml" xpointer="port"/>
189
<term><option>--check</option></term>
192
Run the server’s self-tests. This includes any unit
199
<term><option>--debug</option></term>
201
<xi:include href="mandos-options.xml" xpointer="debug"/>
206
<term><option>--debuglevel
207
<replaceable>LEVEL</replaceable></option></term>
210
Set the debugging log level.
211
<replaceable>LEVEL</replaceable> is a string, one of
212
<quote><literal>CRITICAL</literal></quote>,
213
<quote><literal>ERROR</literal></quote>,
214
<quote><literal>WARNING</literal></quote>,
215
<quote><literal>INFO</literal></quote>, or
216
<quote><literal>DEBUG</literal></quote>, in order of
217
increasing verbosity. The default level is
218
<quote><literal>WARNING</literal></quote>.
224
<term><option>--priority <replaceable>
225
PRIORITY</replaceable></option></term>
227
<xi:include href="mandos-options.xml" xpointer="priority"/>
232
<term><option>--servicename
233
<replaceable>NAME</replaceable></option></term>
235
<xi:include href="mandos-options.xml"
236
xpointer="servicename"/>
241
<term><option>--configdir
242
<replaceable>DIRECTORY</replaceable></option></term>
245
Directory to search for configuration files. Default is
246
<quote><literal>/etc/mandos</literal></quote>. See
247
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
248
<manvolnum>5</manvolnum></citerefentry> and <citerefentry>
249
<refentrytitle>mandos-clients.conf</refentrytitle>
250
<manvolnum>5</manvolnum></citerefentry>.
256
<term><option>--version</option></term>
259
Prints the program version and exit.
265
<term><option>--no-dbus</option></term>
267
<xi:include href="mandos-options.xml" xpointer="dbus"/>
269
See also <xref linkend="dbus_interface"/>.
275
<term><option>--no-ipv6</option></term>
277
<xi:include href="mandos-options.xml" xpointer="ipv6"/>
282
<term><option>--no-restore</option></term>
284
<xi:include href="mandos-options.xml" xpointer="restore"/>
290
<refsect1 id="overview">
291
<title>OVERVIEW</title>
292
<xi:include href="overview.xml"/>
294
This program is the server part. It is a normal server program
295
and will run in a normal system environment, not in an initial
296
<acronym>RAM</acronym> disk environment.
300
<refsect1 id="protocol">
301
<title>NETWORK PROTOCOL</title>
303
The Mandos server announces itself as a Zeroconf service of type
304
<quote><literal>_mandos._tcp</literal></quote>. The Mandos
305
client connects to the announced address and port, and sends a
306
line of text where the first whitespace-separated field is the
307
protocol version, which currently is
308
<quote><literal>1</literal></quote>. The client and server then
309
start a TLS protocol handshake with a slight quirk: the Mandos
310
server program acts as a TLS <quote>client</quote> while the
311
connecting Mandos client acts as a TLS <quote>server</quote>.
312
The Mandos client must supply an OpenPGP certificate, and the
313
fingerprint of this certificate is used by the Mandos server to
314
look up (in a list read from <filename>clients.conf</filename>
315
at start time) which binary blob to give the client. No other
316
authentication or authorization is done by the server.
319
<title>Mandos Protocol (Version 1)</title><tgroup cols="3"><thead>
321
<entry>Mandos Client</entry>
322
<entry>Direction</entry>
323
<entry>Mandos Server</entry>
327
<entry>Connect</entry>
328
<entry>-><!-- → --></entry>
331
<entry><quote><literal>1\r\n</literal></quote></entry>
332
<entry>-><!-- → --></entry>
335
<entry>TLS handshake <emphasis>as TLS <quote>server</quote>
337
<entry><-><!-- ⟷ --></entry>
338
<entry>TLS handshake <emphasis>as TLS <quote>client</quote>
342
<entry>OpenPGP public key (part of TLS handshake)</entry>
343
<entry>-><!-- → --></entry>
347
<entry><-<!-- ← --></entry>
348
<entry>Binary blob (client will assume OpenPGP data)</entry>
352
<entry><-<!-- ← --></entry>
355
</tbody></tgroup></table>
358
<refsect1 id="checking">
359
<title>CHECKING</title>
361
The server will, by default, continually check that the clients
362
are still up. If a client has not been confirmed as being up
363
for some time, the client is assumed to be compromised and is no
364
longer eligible to receive the encrypted password. (Manual
365
intervention is required to re-enable a client.) The timeout,
366
extended timeout, checker program, and interval between checks
367
can be configured both globally and per client; see
368
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
369
<manvolnum>5</manvolnum></citerefentry>. A client successfully
370
receiving its password will also be treated as a successful
375
<refsect1 id="approval">
376
<title>APPROVAL</title>
378
The server can be configured to require manual approval for a
379
client before it is sent its secret. The delay to wait for such
380
approval and the default action (approve or deny) can be
381
configured both globally and per client; see <citerefentry>
382
<refentrytitle>mandos-clients.conf</refentrytitle>
383
<manvolnum>5</manvolnum></citerefentry>. By default all clients
384
will be approved immediately without delay.
387
This can be used to deny a client its secret if not manually
388
approved within a specified time. It can also be used to make
389
the server delay before giving a client its secret, allowing
390
optional manual denying of this specific client.
395
<refsect1 id="logging">
396
<title>LOGGING</title>
398
The server will send log message with various severity levels to
399
<filename>/dev/log</filename>. With the
400
<option>--debug</option> option, it will log even more messages,
401
and also show them on the console.
405
<refsect1 id="dbus_interface">
406
<title>D-BUS INTERFACE</title>
408
The server will by default provide a D-Bus system bus interface.
409
This interface will only be accessible by the root user or a
410
Mandos-specific user, if such a user exists. For documentation
411
of the D-Bus API, see the file <filename>DBUS-API</filename>.
415
<refsect1 id="exit_status">
416
<title>EXIT STATUS</title>
418
The server will exit with a non-zero exit status only when a
419
critical error is encountered.
423
<refsect1 id="environment">
424
<title>ENVIRONMENT</title>
427
<term><envar>PATH</envar></term>
430
To start the configured checker (see <xref
431
linkend="checking"/>), the server uses
432
<filename>/bin/sh</filename>, which in turn uses
433
<varname>PATH</varname> to search for matching commands if
434
an absolute path is not given. See <citerefentry>
435
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
443
<refsect1 id="files">
446
Use the <option>--configdir</option> option to change where
447
<command>&COMMANDNAME;</command> looks for its configurations
448
files. The default file names are listed here.
452
<term><filename>/etc/mandos/mandos.conf</filename></term>
455
Server-global settings. See
456
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
457
<manvolnum>5</manvolnum></citerefentry> for details.
462
<term><filename>/etc/mandos/clients.conf</filename></term>
465
List of clients and client-specific settings. See
466
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
467
<manvolnum>5</manvolnum></citerefentry> for details.
472
<term><filename>/var/run/mandos.pid</filename></term>
475
The file containing the process id of the
476
<command>&COMMANDNAME;</command> process started last.
481
<term><filename>/dev/log</filename></term>
484
The Unix domain socket to where local syslog messages are
490
<term><filename>/bin/sh</filename></term>
493
This is used to start the configured checker command for
494
each client. See <citerefentry>
495
<refentrytitle>mandos-clients.conf</refentrytitle>
496
<manvolnum>5</manvolnum></citerefentry> for details.
506
This server might, on especially fatal errors, emit a Python
507
backtrace. This could be considered a feature.
510
Currently, if a client is disabled due to having timed out, the
511
server does not record this fact onto permanent storage. This
512
has some security implications, see <xref linkend="clients"/>.
515
There is no fine-grained control over logging and debug output.
518
Debug mode is conflated with running in the foreground.
521
This server does not check the expire time of clients’ OpenPGP
526
<refsect1 id="example">
527
<title>EXAMPLE</title>
530
Normal invocation needs no options:
533
<userinput>&COMMANDNAME;</userinput>
538
Run the server in debug mode, read configuration files from
539
the <filename>~/mandos</filename> directory, and use the
540
Zeroconf service name <quote>Test</quote> to not collide with
541
any other official Mandos server on this host:
545
<!-- do not wrap this line -->
546
<userinput>&COMMANDNAME; --debug --configdir ~/mandos --servicename Test</userinput>
552
Run the server normally, but only listen to one interface and
553
only on the link-local address on that interface:
557
<!-- do not wrap this line -->
558
<userinput>&COMMANDNAME; --interface eth7 --address fe80::aede:48ff:fe71:f6f2</userinput>
564
<refsect1 id="security">
565
<title>SECURITY</title>
566
<refsect2 id="server">
567
<title>SERVER</title>
569
Running this <command>&COMMANDNAME;</command> server program
570
should not in itself present any security risk to the host
571
computer running it. The program switches to a non-root user
575
<refsect2 id="clients">
576
<title>CLIENTS</title>
578
The server only gives out its stored data to clients which
579
does have the OpenPGP key of the stored fingerprint. This is
580
guaranteed by the fact that the client sends its OpenPGP
581
public key in the TLS handshake; this ensures it to be
582
genuine. The server computes the fingerprint of the key
583
itself and looks up the fingerprint in its list of
584
clients. The <filename>clients.conf</filename> file (see
585
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
586
<manvolnum>5</manvolnum></citerefentry>)
587
<emphasis>must</emphasis> be made non-readable by anyone
588
except the user starting the server (usually root).
591
As detailed in <xref linkend="checking"/>, the status of all
592
client computers will continually be checked and be assumed
593
compromised if they are gone for too long.
596
If a client is compromised, its downtime should be duly noted
597
by the server which would therefore disable the client. But
598
if the server was ever restarted, it would re-read its client
599
list from its configuration file and again regard all clients
600
therein as enabled, and hence eligible to receive their
601
passwords. Therefore, be careful when restarting servers if
602
it is suspected that a client has, in fact, been compromised
603
by parties who may now be running a fake Mandos client with
604
the keys from the non-encrypted initial <acronym>RAM</acronym>
605
image of the client host. What should be done in that case
606
(if restarting the server program really is necessary) is to
607
stop the server program, edit the configuration file to omit
608
any suspect clients, and restart the server program.
611
For more details on client-side security, see
612
<citerefentry><refentrytitle>mandos-client</refentrytitle>
613
<manvolnum>8mandos</manvolnum></citerefentry>.
618
<refsect1 id="see_also">
619
<title>SEE ALSO</title>
621
<citerefentry><refentrytitle>intro</refentrytitle>
622
<manvolnum>8mandos</manvolnum></citerefentry>,
623
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
624
<manvolnum>5</manvolnum></citerefentry>,
625
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
626
<manvolnum>5</manvolnum></citerefentry>,
627
<citerefentry><refentrytitle>mandos-client</refentrytitle>
628
<manvolnum>8mandos</manvolnum></citerefentry>,
629
<citerefentry><refentrytitle>sh</refentrytitle>
630
<manvolnum>1</manvolnum></citerefentry>
635
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
639
Zeroconf is the network protocol standard used by clients
640
for finding this Mandos server on the local network.
646
<ulink url="http://www.avahi.org/">Avahi</ulink>
650
Avahi is the library this server calls to implement
651
Zeroconf service announcements.
657
<ulink url="http://www.gnu.org/software/gnutls/"
662
GnuTLS is the library this server uses to implement TLS for
663
communicating securely with the client, and at the same time
664
confidently get the client’s public OpenPGP key.
670
RFC 4291: <citetitle>IP Version 6 Addressing
671
Architecture</citetitle>
676
<term>Section 2.2: <citetitle>Text Representation of
677
Addresses</citetitle></term>
678
<listitem><para/></listitem>
681
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
682
Address</citetitle></term>
683
<listitem><para/></listitem>
686
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
687
Addresses</citetitle></term>
690
The clients use IPv6 link-local addresses, which are
691
immediately usable since a link-local addresses is
692
automatically assigned to a network interfaces when it
702
RFC 4346: <citetitle>The Transport Layer Security (TLS)
703
Protocol Version 1.1</citetitle>
707
TLS 1.1 is the protocol implemented by GnuTLS.
713
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
717
The data sent to clients is binary encrypted OpenPGP data.
723
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
728
This is implemented by GnuTLS and used by this server so
729
that OpenPGP keys can be used.
736
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