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>
99
<command>&COMMANDNAME;</command>
101
<arg choice="plain"><option>--help</option></arg>
102
<arg choice="plain"><option>-h</option></arg>
106
<command>&COMMANDNAME;</command>
107
<arg choice="plain"><option>--version</option></arg>
110
<command>&COMMANDNAME;</command>
111
<arg choice="plain"><option>--check</option></arg>
80
115
<refsect1 id="description">
81
116
<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
118
<command>&COMMANDNAME;</command> is a server daemon which
119
handles incoming request for passwords for a pre-defined list of
120
client host computers. The Mandos server uses Zeroconf to
121
announce itself on the local network, and uses TLS to
122
communicate securely with and to authenticate the clients. The
123
Mandos server uses IPv6 to allow Mandos clients to use IPv6
124
link-local addresses, since the clients will probably not have
125
any other addresses configured (see <xref linkend="overview"/>).
126
Any authenticated client is then given the stored pre-encrypted
127
password for that specific client.
131
<refsect1 id="purpose">
132
<title>PURPOSE</title>
134
The purpose of this is to enable <emphasis>remote and unattended
135
rebooting</emphasis> of client host computer with an
136
<emphasis>encrypted root file system</emphasis>. See <xref
137
linkend="overview"/> for details.
141
<refsect1 id="options">
142
<title>OPTIONS</title>
145
<term><option>--help</option></term>
146
<term><option>-h</option></term>
149
Show a help message and exit
155
<term><option>--interface</option>
156
<replaceable>NAME</replaceable></term>
157
<term><option>-i</option>
158
<replaceable>NAME</replaceable></term>
160
<xi:include href="mandos-options.xml" xpointer="interface"/>
165
<term><option>--address
166
<replaceable>ADDRESS</replaceable></option></term>
168
<replaceable>ADDRESS</replaceable></option></term>
170
<xi:include href="mandos-options.xml" xpointer="address"/>
176
<replaceable>PORT</replaceable></option></term>
178
<replaceable>PORT</replaceable></option></term>
180
<xi:include href="mandos-options.xml" xpointer="port"/>
185
<term><option>--check</option></term>
188
Run the server’s self-tests. This includes any unit
195
<term><option>--debug</option></term>
197
<xi:include href="mandos-options.xml" xpointer="debug"/>
202
<term><option>--debuglevel
203
<replaceable>LEVEL</replaceable></option></term>
206
Set the debugging log level.
207
<replaceable>LEVEL</replaceable> is a string, one of
208
<quote><literal>CRITICAL</literal></quote>,
209
<quote><literal>ERROR</literal></quote>,
210
<quote><literal>WARNING</literal></quote>,
211
<quote><literal>INFO</literal></quote>, or
212
<quote><literal>DEBUG</literal></quote>, in order of
213
increasing verbosity. The default level is
214
<quote><literal>WARNING</literal></quote>.
220
<term><option>--priority <replaceable>
221
PRIORITY</replaceable></option></term>
223
<xi:include href="mandos-options.xml" xpointer="priority"/>
228
<term><option>--servicename
229
<replaceable>NAME</replaceable></option></term>
231
<xi:include href="mandos-options.xml"
232
xpointer="servicename"/>
237
<term><option>--configdir
238
<replaceable>DIRECTORY</replaceable></option></term>
241
Directory to search for configuration files. Default is
242
<quote><literal>/etc/mandos</literal></quote>. See
243
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
244
<manvolnum>5</manvolnum></citerefentry> and <citerefentry>
245
<refentrytitle>mandos-clients.conf</refentrytitle>
246
<manvolnum>5</manvolnum></citerefentry>.
252
<term><option>--version</option></term>
255
Prints the program version and exit.
261
<term><option>--no-dbus</option></term>
263
<xi:include href="mandos-options.xml" xpointer="dbus"/>
265
See also <xref linkend="dbus_interface"/>.
271
<term><option>--no-ipv6</option></term>
273
<xi:include href="mandos-options.xml" xpointer="ipv6"/>
279
<refsect1 id="overview">
280
<title>OVERVIEW</title>
281
<xi:include href="overview.xml"/>
283
This program is the server part. It is a normal server program
284
and will run in a normal system environment, not in an initial
285
<acronym>RAM</acronym> disk environment.
289
<refsect1 id="protocol">
290
<title>NETWORK PROTOCOL</title>
292
The Mandos server announces itself as a Zeroconf service of type
293
<quote><literal>_mandos._tcp</literal></quote>. The Mandos
294
client connects to the announced address and port, and sends a
295
line of text where the first whitespace-separated field is the
296
protocol version, which currently is
297
<quote><literal>1</literal></quote>. The client and server then
298
start a TLS protocol handshake with a slight quirk: the Mandos
299
server program acts as a TLS <quote>client</quote> while the
300
connecting Mandos client acts as a TLS <quote>server</quote>.
301
The Mandos client must supply an OpenPGP certificate, and the
302
fingerprint of this certificate is used by the Mandos server to
303
look up (in a list read from <filename>clients.conf</filename>
304
at start time) which binary blob to give the client. No other
305
authentication or authorization is done by the server.
308
<title>Mandos Protocol (Version 1)</title><tgroup cols="3"><thead>
310
<entry>Mandos Client</entry>
311
<entry>Direction</entry>
312
<entry>Mandos Server</entry>
316
<entry>Connect</entry>
317
<entry>-><!-- → --></entry>
320
<entry><quote><literal>1\r\n</literal></quote></entry>
321
<entry>-><!-- → --></entry>
324
<entry>TLS handshake <emphasis>as TLS <quote>server</quote>
326
<entry><-><!-- ⟷ --></entry>
327
<entry>TLS handshake <emphasis>as TLS <quote>client</quote>
331
<entry>OpenPGP public key (part of TLS handshake)</entry>
332
<entry>-><!-- → --></entry>
336
<entry><-<!-- ← --></entry>
337
<entry>Binary blob (client will assume OpenPGP data)</entry>
341
<entry><-<!-- ← --></entry>
344
</tbody></tgroup></table>
347
<refsect1 id="checking">
348
<title>CHECKING</title>
350
The server will, by default, continually check that the clients
351
are still up. If a client has not been confirmed as being up
352
for some time, the client is assumed to be compromised and is no
353
longer eligible to receive the encrypted password. (Manual
354
intervention is required to re-enable a client.) The timeout,
355
checker program, and interval between checks can be configured
356
both globally and per client; see <citerefentry>
357
<refentrytitle>mandos-clients.conf</refentrytitle>
358
<manvolnum>5</manvolnum></citerefentry>. A client successfully
359
receiving its password will also be treated as a successful
364
<refsect1 id="approval">
365
<title>APPROVAL</title>
367
The server can be configured to require manual approval for a
368
client before it is sent its secret. The delay to wait for such
369
approval and the default action (approve or deny) can be
370
configured both globally and per client; see <citerefentry>
371
<refentrytitle>mandos-clients.conf</refentrytitle>
372
<manvolnum>5</manvolnum></citerefentry>. By default all clients
373
will be approved immediately without delay.
376
This can be used to deny a client its secret if not manually
377
approved within a specified time. It can also be used to make
378
the server delay before giving a client its secret, allowing
379
optional manual denying of this specific client.
384
<refsect1 id="logging">
385
<title>LOGGING</title>
387
The server will send log message with various severity levels to
388
<filename>/dev/log</filename>. With the
389
<option>--debug</option> option, it will log even more messages,
390
and also show them on the console.
394
<refsect1 id="dbus_interface">
395
<title>D-BUS INTERFACE</title>
397
The server will by default provide a D-Bus system bus interface.
398
This interface will only be accessible by the root user or a
399
Mandos-specific user, if such a user exists. For documentation
400
of the D-Bus API, see the file <filename>DBUS-API</filename>.
404
<refsect1 id="exit_status">
405
<title>EXIT STATUS</title>
407
The server will exit with a non-zero exit status only when a
408
critical error is encountered.
412
<refsect1 id="environment">
413
<title>ENVIRONMENT</title>
416
<term><envar>PATH</envar></term>
419
To start the configured checker (see <xref
420
linkend="checking"/>), the server uses
421
<filename>/bin/sh</filename>, which in turn uses
422
<varname>PATH</varname> to search for matching commands if
423
an absolute path is not given. See <citerefentry>
424
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
432
<refsect1 id="files">
435
Use the <option>--configdir</option> option to change where
436
<command>&COMMANDNAME;</command> looks for its configurations
437
files. The default file names are listed here.
441
<term><filename>/etc/mandos/mandos.conf</filename></term>
444
Server-global settings. See
445
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
446
<manvolnum>5</manvolnum></citerefentry> for details.
451
<term><filename>/etc/mandos/clients.conf</filename></term>
454
List of clients and client-specific settings. See
455
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
456
<manvolnum>5</manvolnum></citerefentry> for details.
461
<term><filename>/var/run/mandos.pid</filename></term>
464
The file containing the process id of the
465
<command>&COMMANDNAME;</command> process started last.
470
<term><filename>/dev/log</filename></term>
473
The Unix domain socket to where local syslog messages are
479
<term><filename>/bin/sh</filename></term>
482
This is used to start the configured checker command for
483
each client. See <citerefentry>
484
<refentrytitle>mandos-clients.conf</refentrytitle>
485
<manvolnum>5</manvolnum></citerefentry> for details.
495
This server might, on especially fatal errors, emit a Python
496
backtrace. This could be considered a feature.
499
Currently, if a client is disabled due to having timed out, the
500
server does not record this fact onto permanent storage. This
501
has some security implications, see <xref linkend="clients"/>.
504
There is no fine-grained control over logging and debug output.
507
Debug mode is conflated with running in the foreground.
510
The console log messages do not show a time stamp.
513
This server does not check the expire time of clients’ OpenPGP
518
<refsect1 id="example">
519
<title>EXAMPLE</title>
522
Normal invocation needs no options:
525
<userinput>&COMMANDNAME;</userinput>
530
Run the server in debug mode, read configuration files from
531
the <filename>~/mandos</filename> directory, and use the
532
Zeroconf service name <quote>Test</quote> to not collide with
533
any other official Mandos server on this host:
537
<!-- do not wrap this line -->
538
<userinput>&COMMANDNAME; --debug --configdir ~/mandos --servicename Test</userinput>
544
Run the server normally, but only listen to one interface and
545
only on the link-local address on that interface:
549
<!-- do not wrap this line -->
550
<userinput>&COMMANDNAME; --interface eth7 --address fe80::aede:48ff:fe71:f6f2</userinput>
556
<refsect1 id="security">
557
<title>SECURITY</title>
558
<refsect2 id="server">
559
<title>SERVER</title>
561
Running this <command>&COMMANDNAME;</command> server program
562
should not in itself present any security risk to the host
563
computer running it. The program switches to a non-root user
567
<refsect2 id="clients">
568
<title>CLIENTS</title>
570
The server only gives out its stored data to clients which
571
does have the OpenPGP key of the stored fingerprint. This is
572
guaranteed by the fact that the client sends its OpenPGP
573
public key in the TLS handshake; this ensures it to be
574
genuine. The server computes the fingerprint of the key
575
itself and looks up the fingerprint in its list of
576
clients. The <filename>clients.conf</filename> file (see
577
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
578
<manvolnum>5</manvolnum></citerefentry>)
579
<emphasis>must</emphasis> be made non-readable by anyone
580
except the user starting the server (usually root).
583
As detailed in <xref linkend="checking"/>, the status of all
584
client computers will continually be checked and be assumed
585
compromised if they are gone for too long.
588
If a client is compromised, its downtime should be duly noted
589
by the server which would therefore disable the client. But
590
if the server was ever restarted, it would re-read its client
591
list from its configuration file and again regard all clients
592
therein as enabled, and hence eligible to receive their
593
passwords. Therefore, be careful when restarting servers if
594
it is suspected that a client has, in fact, been compromised
595
by parties who may now be running a fake Mandos client with
596
the keys from the non-encrypted initial <acronym>RAM</acronym>
597
image of the client host. What should be done in that case
598
(if restarting the server program really is necessary) is to
599
stop the server program, edit the configuration file to omit
600
any suspect clients, and restart the server program.
603
For more details on client-side security, see
604
<citerefentry><refentrytitle>mandos-client</refentrytitle>
605
<manvolnum>8mandos</manvolnum></citerefentry>.
610
<refsect1 id="see_also">
611
<title>SEE ALSO</title>
614
<refentrytitle>mandos-clients.conf</refentrytitle>
615
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
616
<refentrytitle>mandos.conf</refentrytitle>
617
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
618
<refentrytitle>mandos-client</refentrytitle>
619
<manvolnum>8mandos</manvolnum></citerefentry>, <citerefentry>
620
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
626
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
630
Zeroconf is the network protocol standard used by clients
631
for finding this Mandos server on the local network.
637
<ulink url="http://www.avahi.org/">Avahi</ulink>
641
Avahi is the library this server calls to implement
642
Zeroconf service announcements.
648
<ulink url="http://www.gnu.org/software/gnutls/"
653
GnuTLS is the library this server uses to implement TLS for
654
communicating securely with the client, and at the same time
655
confidently get the client’s public OpenPGP key.
661
RFC 4291: <citetitle>IP Version 6 Addressing
662
Architecture</citetitle>
667
<term>Section 2.2: <citetitle>Text Representation of
668
Addresses</citetitle></term>
669
<listitem><para/></listitem>
672
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
673
Address</citetitle></term>
674
<listitem><para/></listitem>
677
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
678
Addresses</citetitle></term>
681
The clients use IPv6 link-local addresses, which are
682
immediately usable since a link-local addresses is
683
automatically assigned to a network interfaces when it
693
RFC 4346: <citetitle>The Transport Layer Security (TLS)
694
Protocol Version 1.1</citetitle>
698
TLS 1.1 is the protocol implemented by GnuTLS.
704
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
708
The data sent to clients is binary encrypted OpenPGP data.
714
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
719
This is implemented by GnuTLS and used by this server so
720
that OpenPGP keys can be used.
727
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