67
49
<refname><command>&COMMANDNAME;</command></refname>
69
Sends encrypted passwords to authenticated mandos clients
51
Gives encrypted passwords to authenticated Mandos clients
75
57
<command>&COMMANDNAME;</command>
76
<arg choice='opt' rep='repeat'>OPTION</arg>
59
<arg choice="plain"><option>--interface
60
<replaceable>NAME</replaceable></option></arg>
61
<arg choice="plain"><option>-i
62
<replaceable>NAME</replaceable></option></arg>
66
<arg choice="plain"><option>--address
67
<replaceable>ADDRESS</replaceable></option></arg>
68
<arg choice="plain"><option>-a
69
<replaceable>ADDRESS</replaceable></option></arg>
73
<arg choice="plain"><option>--port
74
<replaceable>PORT</replaceable></option></arg>
75
<arg choice="plain"><option>-p
76
<replaceable>PORT</replaceable></option></arg>
79
<arg><option>--priority
80
<replaceable>PRIORITY</replaceable></option></arg>
82
<arg><option>--servicename
83
<replaceable>NAME</replaceable></option></arg>
85
<arg><option>--configdir
86
<replaceable>DIRECTORY</replaceable></option></arg>
88
<arg><option>--debug</option></arg>
90
<arg><option>--debuglevel
91
<replaceable>LEVEL</replaceable></option></arg>
93
<arg><option>--no-dbus</option></arg>
95
<arg><option>--no-ipv6</option></arg>
98
<command>&COMMANDNAME;</command>
100
<arg choice="plain"><option>--help</option></arg>
101
<arg choice="plain"><option>-h</option></arg>
105
<command>&COMMANDNAME;</command>
106
<arg choice="plain"><option>--version</option></arg>
109
<command>&COMMANDNAME;</command>
110
<arg choice="plain"><option>--check</option></arg>
80
114
<refsect1 id="description">
81
115
<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
117
<command>&COMMANDNAME;</command> is a server daemon which
118
handles incoming request for passwords for a pre-defined list of
119
client host computers. The Mandos server uses Zeroconf to
120
announce itself on the local network, and uses TLS to
121
communicate securely with and to authenticate the clients. The
122
Mandos server uses IPv6 to allow Mandos clients to use IPv6
123
link-local addresses, since the clients will probably not have
124
any other addresses configured (see <xref linkend="overview"/>).
125
Any authenticated client is then given the stored pre-encrypted
126
password for that specific client.
130
<refsect1 id="purpose">
131
<title>PURPOSE</title>
133
The purpose of this is to enable <emphasis>remote and unattended
134
rebooting</emphasis> of client host computer with an
135
<emphasis>encrypted root file system</emphasis>. See <xref
136
linkend="overview"/> for details.
140
<refsect1 id="options">
141
<title>OPTIONS</title>
144
<term><option>--help</option></term>
145
<term><option>-h</option></term>
148
Show a help message and exit
154
<term><option>--interface</option>
155
<replaceable>NAME</replaceable></term>
156
<term><option>-i</option>
157
<replaceable>NAME</replaceable></term>
159
<xi:include href="mandos-options.xml" xpointer="interface"/>
164
<term><option>--address
165
<replaceable>ADDRESS</replaceable></option></term>
167
<replaceable>ADDRESS</replaceable></option></term>
169
<xi:include href="mandos-options.xml" xpointer="address"/>
175
<replaceable>PORT</replaceable></option></term>
177
<replaceable>PORT</replaceable></option></term>
179
<xi:include href="mandos-options.xml" xpointer="port"/>
184
<term><option>--check</option></term>
187
Run the server’s self-tests. This includes any unit
194
<term><option>--debug</option></term>
196
<xi:include href="mandos-options.xml" xpointer="debug"/>
201
<term><option>--debuglevel
202
<replaceable>LEVEL</replaceable></option></term>
205
Set the debugging log level.
206
<replaceable>LEVEL</replaceable> is a string, one of
207
<quote><literal>CRITICAL</literal></quote>,
208
<quote><literal>ERROR</literal></quote>,
209
<quote><literal>WARNING</literal></quote>,
210
<quote><literal>INFO</literal></quote>, or
211
<quote><literal>DEBUG</literal></quote>, in order of
212
increasing verbosity. The default level is
213
<quote><literal>WARNING</literal></quote>.
219
<term><option>--priority <replaceable>
220
PRIORITY</replaceable></option></term>
222
<xi:include href="mandos-options.xml" xpointer="priority"/>
227
<term><option>--servicename
228
<replaceable>NAME</replaceable></option></term>
230
<xi:include href="mandos-options.xml"
231
xpointer="servicename"/>
236
<term><option>--configdir
237
<replaceable>DIRECTORY</replaceable></option></term>
240
Directory to search for configuration files. Default is
241
<quote><literal>/etc/mandos</literal></quote>. See
242
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
243
<manvolnum>5</manvolnum></citerefentry> and <citerefentry>
244
<refentrytitle>mandos-clients.conf</refentrytitle>
245
<manvolnum>5</manvolnum></citerefentry>.
251
<term><option>--version</option></term>
254
Prints the program version and exit.
260
<term><option>--no-dbus</option></term>
262
<xi:include href="mandos-options.xml" xpointer="dbus"/>
264
See also <xref linkend="dbus_interface"/>.
270
<term><option>--no-ipv6</option></term>
272
<xi:include href="mandos-options.xml" xpointer="ipv6"/>
278
<refsect1 id="overview">
279
<title>OVERVIEW</title>
280
<xi:include href="overview.xml"/>
282
This program is the server part. It is a normal server program
283
and will run in a normal system environment, not in an initial
284
<acronym>RAM</acronym> disk environment.
288
<refsect1 id="protocol">
289
<title>NETWORK PROTOCOL</title>
291
The Mandos server announces itself as a Zeroconf service of type
292
<quote><literal>_mandos._tcp</literal></quote>. The Mandos
293
client connects to the announced address and port, and sends a
294
line of text where the first whitespace-separated field is the
295
protocol version, which currently is
296
<quote><literal>1</literal></quote>. The client and server then
297
start a TLS protocol handshake with a slight quirk: the Mandos
298
server program acts as a TLS <quote>client</quote> while the
299
connecting Mandos client acts as a TLS <quote>server</quote>.
300
The Mandos client must supply an OpenPGP certificate, and the
301
fingerprint of this certificate is used by the Mandos server to
302
look up (in a list read from <filename>clients.conf</filename>
303
at start time) which binary blob to give the client. No other
304
authentication or authorization is done by the server.
307
<title>Mandos Protocol (Version 1)</title><tgroup cols="3"><thead>
309
<entry>Mandos Client</entry>
310
<entry>Direction</entry>
311
<entry>Mandos Server</entry>
315
<entry>Connect</entry>
316
<entry>-><!-- → --></entry>
319
<entry><quote><literal>1\r\n</literal></quote></entry>
320
<entry>-><!-- → --></entry>
323
<entry>TLS handshake <emphasis>as TLS <quote>server</quote>
325
<entry><-><!-- ⟷ --></entry>
326
<entry>TLS handshake <emphasis>as TLS <quote>client</quote>
330
<entry>OpenPGP public key (part of TLS handshake)</entry>
331
<entry>-><!-- → --></entry>
335
<entry><-<!-- ← --></entry>
336
<entry>Binary blob (client will assume OpenPGP data)</entry>
340
<entry><-<!-- ← --></entry>
343
</tbody></tgroup></table>
346
<refsect1 id="checking">
347
<title>CHECKING</title>
349
The server will, by default, continually check that the clients
350
are still up. If a client has not been confirmed as being up
351
for some time, the client is assumed to be compromised and is no
352
longer eligible to receive the encrypted password. (Manual
353
intervention is required to re-enable a client.) The timeout,
354
checker program, and interval between checks can be configured
355
both globally and per client; see <citerefentry>
356
<refentrytitle>mandos-clients.conf</refentrytitle>
357
<manvolnum>5</manvolnum></citerefentry>. A client successfully
358
receiving its password will also be treated as a successful
363
<refsect1 id="approval">
364
<title>APPROVAL</title>
366
The server can be configured to require manual approval for a
367
client before it is sent its secret. The delay to wait for such
368
approval and the default action (approve or deny) can be
369
configured both globally and per client; see <citerefentry>
370
<refentrytitle>mandos-clients.conf</refentrytitle>
371
<manvolnum>5</manvolnum></citerefentry>. By default all clients
372
will be approved immediately without delay.
375
This can be used to deny a client its secret if not manually
376
approved within a specified time. It can also be used to make
377
the server delay before giving a client its secret, allowing
378
optional manual denying of this specific client.
383
<refsect1 id="logging">
384
<title>LOGGING</title>
386
The server will send log message with various severity levels to
387
<filename>/dev/log</filename>. With the
388
<option>--debug</option> option, it will log even more messages,
389
and also show them on the console.
393
<refsect1 id="dbus_interface">
394
<title>D-BUS INTERFACE</title>
396
The server will by default provide a D-Bus system bus interface.
397
This interface will only be accessible by the root user or a
398
Mandos-specific user, if such a user exists. For documentation
399
of the D-Bus API, see the file <filename>DBUS-API</filename>.
403
<refsect1 id="exit_status">
404
<title>EXIT STATUS</title>
406
The server will exit with a non-zero exit status only when a
407
critical error is encountered.
411
<refsect1 id="environment">
412
<title>ENVIRONMENT</title>
415
<term><envar>PATH</envar></term>
418
To start the configured checker (see <xref
419
linkend="checking"/>), the server uses
420
<filename>/bin/sh</filename>, which in turn uses
421
<varname>PATH</varname> to search for matching commands if
422
an absolute path is not given. See <citerefentry>
423
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
431
<refsect1 id="files">
434
Use the <option>--configdir</option> option to change where
435
<command>&COMMANDNAME;</command> looks for its configurations
436
files. The default file names are listed here.
440
<term><filename>/etc/mandos/mandos.conf</filename></term>
443
Server-global settings. See
444
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
445
<manvolnum>5</manvolnum></citerefentry> for details.
450
<term><filename>/etc/mandos/clients.conf</filename></term>
453
List of clients and client-specific settings. See
454
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
455
<manvolnum>5</manvolnum></citerefentry> for details.
460
<term><filename>/var/run/mandos.pid</filename></term>
463
The file containing the process id of the
464
<command>&COMMANDNAME;</command> process started last.
469
<term><filename>/dev/log</filename></term>
472
The Unix domain socket to where local syslog messages are
478
<term><filename>/bin/sh</filename></term>
481
This is used to start the configured checker command for
482
each client. See <citerefentry>
483
<refentrytitle>mandos-clients.conf</refentrytitle>
484
<manvolnum>5</manvolnum></citerefentry> for details.
494
This server might, on especially fatal errors, emit a Python
495
backtrace. This could be considered a feature.
498
Currently, if a client is disabled due to having timed out, the
499
server does not record this fact onto permanent storage. This
500
has some security implications, see <xref linkend="clients"/>.
503
There is no fine-grained control over logging and debug output.
506
Debug mode is conflated with running in the foreground.
509
The console log messages do not show a time stamp.
512
This server does not check the expire time of clients’ OpenPGP
517
<refsect1 id="example">
518
<title>EXAMPLE</title>
521
Normal invocation needs no options:
524
<userinput>&COMMANDNAME;</userinput>
529
Run the server in debug mode, read configuration files from
530
the <filename>~/mandos</filename> directory, and use the
531
Zeroconf service name <quote>Test</quote> to not collide with
532
any other official Mandos server on this host:
536
<!-- do not wrap this line -->
537
<userinput>&COMMANDNAME; --debug --configdir ~/mandos --servicename Test</userinput>
543
Run the server normally, but only listen to one interface and
544
only on the link-local address on that interface:
548
<!-- do not wrap this line -->
549
<userinput>&COMMANDNAME; --interface eth7 --address fe80::aede:48ff:fe71:f6f2</userinput>
555
<refsect1 id="security">
556
<title>SECURITY</title>
557
<refsect2 id="server">
558
<title>SERVER</title>
560
Running this <command>&COMMANDNAME;</command> server program
561
should not in itself present any security risk to the host
562
computer running it. The program switches to a non-root user
566
<refsect2 id="clients">
567
<title>CLIENTS</title>
569
The server only gives out its stored data to clients which
570
does have the OpenPGP key of the stored fingerprint. This is
571
guaranteed by the fact that the client sends its OpenPGP
572
public key in the TLS handshake; this ensures it to be
573
genuine. The server computes the fingerprint of the key
574
itself and looks up the fingerprint in its list of
575
clients. The <filename>clients.conf</filename> file (see
576
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
577
<manvolnum>5</manvolnum></citerefentry>)
578
<emphasis>must</emphasis> be made non-readable by anyone
579
except the user starting the server (usually root).
582
As detailed in <xref linkend="checking"/>, the status of all
583
client computers will continually be checked and be assumed
584
compromised if they are gone for too long.
587
If a client is compromised, its downtime should be duly noted
588
by the server which would therefore disable the client. But
589
if the server was ever restarted, it would re-read its client
590
list from its configuration file and again regard all clients
591
therein as enabled, and hence eligible to receive their
592
passwords. Therefore, be careful when restarting servers if
593
it is suspected that a client has, in fact, been compromised
594
by parties who may now be running a fake Mandos client with
595
the keys from the non-encrypted initial <acronym>RAM</acronym>
596
image of the client host. What should be done in that case
597
(if restarting the server program really is necessary) is to
598
stop the server program, edit the configuration file to omit
599
any suspect clients, and restart the server program.
602
For more details on client-side security, see
603
<citerefentry><refentrytitle>mandos-client</refentrytitle>
604
<manvolnum>8mandos</manvolnum></citerefentry>.
609
<refsect1 id="see_also">
610
<title>SEE ALSO</title>
613
<refentrytitle>mandos-clients.conf</refentrytitle>
614
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
615
<refentrytitle>mandos.conf</refentrytitle>
616
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
617
<refentrytitle>mandos-client</refentrytitle>
618
<manvolnum>8mandos</manvolnum></citerefentry>, <citerefentry>
619
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
625
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
629
Zeroconf is the network protocol standard used by clients
630
for finding this Mandos server on the local network.
636
<ulink url="http://www.avahi.org/">Avahi</ulink>
640
Avahi is the library this server calls to implement
641
Zeroconf service announcements.
647
<ulink url="http://www.gnu.org/software/gnutls/"
652
GnuTLS is the library this server uses to implement TLS for
653
communicating securely with the client, and at the same time
654
confidently get the client’s public OpenPGP key.
660
RFC 4291: <citetitle>IP Version 6 Addressing
661
Architecture</citetitle>
666
<term>Section 2.2: <citetitle>Text Representation of
667
Addresses</citetitle></term>
668
<listitem><para/></listitem>
671
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
672
Address</citetitle></term>
673
<listitem><para/></listitem>
676
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
677
Addresses</citetitle></term>
680
The clients use IPv6 link-local addresses, which are
681
immediately usable since a link-local addresses is
682
automatically assigned to a network interfaces when it
692
RFC 4346: <citetitle>The Transport Layer Security (TLS)
693
Protocol Version 1.1</citetitle>
697
TLS 1.1 is the protocol implemented by GnuTLS.
703
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
707
The data sent to clients is binary encrypted OpenPGP data.
713
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
718
This is implemented by GnuTLS and used by this server so
719
that OpenPGP keys can be used.
726
<!-- Local Variables: -->
727
<!-- time-stamp-start: "<!ENTITY TIMESTAMP [\"']" -->
728
<!-- time-stamp-end: "[\"']>" -->
729
<!-- time-stamp-format: "%:y-%02m-%02d" -->