67
48
<refname><command>&COMMANDNAME;</command></refname>
69
Sends encrypted passwords to authenticated mandos clients
50
Gives encrypted passwords to authenticated Mandos clients
75
56
<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'>--check</arg>
93
<command>&COMMANDNAME;</command>
94
<arg choice='plain'>--version</arg>
58
<arg choice="plain"><option>--interface
59
<replaceable>NAME</replaceable></option></arg>
60
<arg choice="plain"><option>-i
61
<replaceable>NAME</replaceable></option></arg>
65
<arg choice="plain"><option>--address
66
<replaceable>ADDRESS</replaceable></option></arg>
67
<arg choice="plain"><option>-a
68
<replaceable>ADDRESS</replaceable></option></arg>
72
<arg choice="plain"><option>--port
73
<replaceable>PORT</replaceable></option></arg>
74
<arg choice="plain"><option>-p
75
<replaceable>PORT</replaceable></option></arg>
78
<arg><option>--priority
79
<replaceable>PRIORITY</replaceable></option></arg>
81
<arg><option>--servicename
82
<replaceable>NAME</replaceable></option></arg>
84
<arg><option>--configdir
85
<replaceable>DIRECTORY</replaceable></option></arg>
87
<arg><option>--debug</option></arg>
89
<arg><option>--no-dbus</option></arg>
91
<arg><option>--no-ipv6</option></arg>
94
<command>&COMMANDNAME;</command>
96
<arg choice="plain"><option>--help</option></arg>
97
<arg choice="plain"><option>-h</option></arg>
101
<command>&COMMANDNAME;</command>
102
<arg choice="plain"><option>--version</option></arg>
105
<command>&COMMANDNAME;</command>
106
<arg choice="plain"><option>--check</option></arg>
98
110
<refsect1 id="description">
99
111
<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
113
<command>&COMMANDNAME;</command> is a server daemon which
114
handles incoming request for passwords for a pre-defined list of
115
client host computers. The Mandos server uses Zeroconf to
116
announce itself on the local network, and uses TLS to
117
communicate securely with and to authenticate the clients. The
118
Mandos server uses IPv6 to allow Mandos clients to use IPv6
119
link-local addresses, since the clients will probably not have
120
any other addresses configured (see <xref linkend="overview"/>).
121
Any authenticated client is then given the stored pre-encrypted
122
password for that specific client.
126
<refsect1 id="purpose">
127
<title>PURPOSE</title>
129
The purpose of this is to enable <emphasis>remote and unattended
130
rebooting</emphasis> of client host computer with an
131
<emphasis>encrypted root file system</emphasis>. See <xref
132
linkend="overview"/> for details.
136
<refsect1 id="options">
137
<title>OPTIONS</title>
140
<term><option>--help</option></term>
141
<term><option>-h</option></term>
144
Show a help message and exit
150
<term><option>--interface</option>
151
<replaceable>NAME</replaceable></term>
152
<term><option>-i</option>
153
<replaceable>NAME</replaceable></term>
155
<xi:include href="mandos-options.xml" xpointer="interface"/>
160
<term><option>--address
161
<replaceable>ADDRESS</replaceable></option></term>
163
<replaceable>ADDRESS</replaceable></option></term>
165
<xi:include href="mandos-options.xml" xpointer="address"/>
171
<replaceable>PORT</replaceable></option></term>
173
<replaceable>PORT</replaceable></option></term>
175
<xi:include href="mandos-options.xml" xpointer="port"/>
180
<term><option>--check</option></term>
183
Run the server’s self-tests. This includes any unit
190
<term><option>--debug</option></term>
192
<xi:include href="mandos-options.xml" xpointer="debug"/>
197
<term><option>--priority <replaceable>
198
PRIORITY</replaceable></option></term>
200
<xi:include href="mandos-options.xml" xpointer="priority"/>
205
<term><option>--servicename
206
<replaceable>NAME</replaceable></option></term>
208
<xi:include href="mandos-options.xml"
209
xpointer="servicename"/>
214
<term><option>--configdir
215
<replaceable>DIRECTORY</replaceable></option></term>
218
Directory to search for configuration files. Default is
219
<quote><literal>/etc/mandos</literal></quote>. See
220
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
221
<manvolnum>5</manvolnum></citerefentry> and <citerefentry>
222
<refentrytitle>mandos-clients.conf</refentrytitle>
223
<manvolnum>5</manvolnum></citerefentry>.
229
<term><option>--version</option></term>
232
Prints the program version and exit.
238
<term><option>--no-dbus</option></term>
240
<xi:include href="mandos-options.xml" xpointer="dbus"/>
242
See also <xref linkend="dbus_interface"/>.
248
<term><option>--no-ipv6</option></term>
250
<xi:include href="mandos-options.xml" xpointer="ipv6"/>
256
<refsect1 id="overview">
257
<title>OVERVIEW</title>
258
<xi:include href="overview.xml"/>
260
This program is the server part. It is a normal server program
261
and will run in a normal system environment, not in an initial
262
<acronym>RAM</acronym> disk environment.
266
<refsect1 id="protocol">
267
<title>NETWORK PROTOCOL</title>
269
The Mandos server announces itself as a Zeroconf service of type
270
<quote><literal>_mandos._tcp</literal></quote>. The Mandos
271
client connects to the announced address and port, and sends a
272
line of text where the first whitespace-separated field is the
273
protocol version, which currently is
274
<quote><literal>1</literal></quote>. The client and server then
275
start a TLS protocol handshake with a slight quirk: the Mandos
276
server program acts as a TLS <quote>client</quote> while the
277
connecting Mandos client acts as a TLS <quote>server</quote>.
278
The Mandos client must supply an OpenPGP certificate, and the
279
fingerprint of this certificate is used by the Mandos server to
280
look up (in a list read from <filename>clients.conf</filename>
281
at start time) which binary blob to give the client. No other
282
authentication or authorization is done by the server.
285
<title>Mandos Protocol (Version 1)</title><tgroup cols="3"><thead>
287
<entry>Mandos Client</entry>
288
<entry>Direction</entry>
289
<entry>Mandos Server</entry>
293
<entry>Connect</entry>
294
<entry>-><!-- → --></entry>
297
<entry><quote><literal>1\r\n</literal></quote></entry>
298
<entry>-><!-- → --></entry>
301
<entry>TLS handshake <emphasis>as TLS <quote>server</quote>
303
<entry><-><!-- ⟷ --></entry>
304
<entry>TLS handshake <emphasis>as TLS <quote>client</quote>
308
<entry>OpenPGP public key (part of TLS handshake)</entry>
309
<entry>-><!-- → --></entry>
313
<entry><-<!-- ← --></entry>
314
<entry>Binary blob (client will assume OpenPGP data)</entry>
318
<entry><-<!-- ← --></entry>
321
</tbody></tgroup></table>
324
<refsect1 id="checking">
325
<title>CHECKING</title>
327
The server will, by default, continually check that the clients
328
are still up. If a client has not been confirmed as being up
329
for some time, the client is assumed to be compromised and is no
330
longer eligible to receive the encrypted password. The timeout,
331
checker program, and interval between checks can be configured
332
both globally and per client; see <citerefentry>
333
<refentrytitle>mandos-clients.conf</refentrytitle>
334
<manvolnum>5</manvolnum></citerefentry>.
338
<refsect1 id="logging">
339
<title>LOGGING</title>
341
The server will send log message with various severity levels to
342
<filename>/dev/log</filename>. With the
343
<option>--debug</option> option, it will log even more messages,
344
and also show them on the console.
348
<refsect1 id="dbus_interface">
349
<title>D-BUS INTERFACE</title>
351
The server will by default provide a D-Bus system bus interface.
352
This interface will only be accessible by the root user or a
353
Mandos-specific user, if such a user exists.
358
<refsect1 id="exit_status">
359
<title>EXIT STATUS</title>
361
The server will exit with a non-zero exit status only when a
362
critical error is encountered.
366
<refsect1 id="environment">
367
<title>ENVIRONMENT</title>
370
<term><envar>PATH</envar></term>
373
To start the configured checker (see <xref
374
linkend="checking"/>), the server uses
375
<filename>/bin/sh</filename>, which in turn uses
376
<varname>PATH</varname> to search for matching commands if
377
an absolute path is not given. See <citerefentry>
378
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
386
<refsect1 id="files">
389
Use the <option>--configdir</option> option to change where
390
<command>&COMMANDNAME;</command> looks for its configurations
391
files. The default file names are listed here.
395
<term><filename>/etc/mandos/mandos.conf</filename></term>
398
Server-global settings. See
399
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
400
<manvolnum>5</manvolnum></citerefentry> for details.
405
<term><filename>/etc/mandos/clients.conf</filename></term>
408
List of clients and client-specific settings. See
409
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
410
<manvolnum>5</manvolnum></citerefentry> for details.
415
<term><filename>/var/run/mandos.pid</filename></term>
418
The file containing the process id of
419
<command>&COMMANDNAME;</command>.
424
<term><filename>/dev/log</filename></term>
427
The Unix domain socket to where local syslog messages are
433
<term><filename>/bin/sh</filename></term>
436
This is used to start the configured checker command for
437
each client. See <citerefentry>
438
<refentrytitle>mandos-clients.conf</refentrytitle>
439
<manvolnum>5</manvolnum></citerefentry> for details.
449
This server might, on especially fatal errors, emit a Python
450
backtrace. This could be considered a feature.
453
Currently, if a client is declared <quote>invalid</quote> due to
454
having timed out, the server does not record this fact onto
455
permanent storage. This has some security implications, see
456
<xref linkend="clients"/>.
459
There is currently no way of querying the server of the current
460
status of clients, other than analyzing its <systemitem
461
class="service">syslog</systemitem> output.
464
There is no fine-grained control over logging and debug output.
467
Debug mode is conflated with running in the foreground.
470
The console log messages do not show a time stamp.
473
This server does not check the expire time of clients’ OpenPGP
478
<refsect1 id="example">
479
<title>EXAMPLE</title>
482
Normal invocation needs no options:
485
<userinput>&COMMANDNAME;</userinput>
490
Run the server in debug mode, read configuration files from
491
the <filename>~/mandos</filename> directory, and use the
492
Zeroconf service name <quote>Test</quote> to not collide with
493
any other official Mandos server on this host:
497
<!-- do not wrap this line -->
498
<userinput>&COMMANDNAME; --debug --configdir ~/mandos --servicename Test</userinput>
504
Run the server normally, but only listen to one interface and
505
only on the link-local address on that interface:
509
<!-- do not wrap this line -->
510
<userinput>&COMMANDNAME; --interface eth7 --address fe80::aede:48ff:fe71:f6f2</userinput>
516
<refsect1 id="security">
517
<title>SECURITY</title>
518
<refsect2 id="server">
519
<title>SERVER</title>
521
Running this <command>&COMMANDNAME;</command> server program
522
should not in itself present any security risk to the host
523
computer running it. The program switches to a non-root user
527
<refsect2 id="clients">
528
<title>CLIENTS</title>
530
The server only gives out its stored data to clients which
531
does have the OpenPGP key of the stored fingerprint. This is
532
guaranteed by the fact that the client sends its OpenPGP
533
public key in the TLS handshake; this ensures it to be
534
genuine. The server computes the fingerprint of the key
535
itself and looks up the fingerprint in its list of
536
clients. The <filename>clients.conf</filename> file (see
537
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
538
<manvolnum>5</manvolnum></citerefentry>)
539
<emphasis>must</emphasis> be made non-readable by anyone
540
except the user starting the server (usually root).
543
As detailed in <xref linkend="checking"/>, the status of all
544
client computers will continually be checked and be assumed
545
compromised if they are gone for too long.
548
If a client is compromised, its downtime should be duly noted
549
by the server which would therefore declare the client
550
invalid. But if the server was ever restarted, it would
551
re-read its client list from its configuration file and again
552
regard all clients therein as valid, and hence eligible to
553
receive their passwords. Therefore, be careful when
554
restarting servers if it is suspected that a client has, in
555
fact, been compromised by parties who may now be running a
556
fake Mandos client with the keys from the non-encrypted
557
initial <acronym>RAM</acronym> image of the client host. What
558
should be done in that case (if restarting the server program
559
really is necessary) is to stop the server program, edit the
560
configuration file to omit any suspect clients, and restart
564
For more details on client-side security, see
565
<citerefentry><refentrytitle>mandos-client</refentrytitle>
566
<manvolnum>8mandos</manvolnum></citerefentry>.
571
<refsect1 id="see_also">
572
<title>SEE ALSO</title>
575
<refentrytitle>mandos-clients.conf</refentrytitle>
576
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
577
<refentrytitle>mandos.conf</refentrytitle>
578
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
579
<refentrytitle>mandos-client</refentrytitle>
580
<manvolnum>8mandos</manvolnum></citerefentry>, <citerefentry>
581
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
587
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
591
Zeroconf is the network protocol standard used by clients
592
for finding this Mandos server on the local network.
598
<ulink url="http://www.avahi.org/">Avahi</ulink>
602
Avahi is the library this server calls to implement
603
Zeroconf service announcements.
609
<ulink url="http://www.gnu.org/software/gnutls/"
614
GnuTLS is the library this server uses to implement TLS for
615
communicating securely with the client, and at the same time
616
confidently get the client’s public OpenPGP key.
622
RFC 4291: <citetitle>IP Version 6 Addressing
623
Architecture</citetitle>
628
<term>Section 2.2: <citetitle>Text Representation of
629
Addresses</citetitle></term>
630
<listitem><para/></listitem>
633
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
634
Address</citetitle></term>
635
<listitem><para/></listitem>
638
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
639
Addresses</citetitle></term>
642
The clients use IPv6 link-local addresses, which are
643
immediately usable since a link-local addresses is
644
automatically assigned to a network interfaces when it
654
RFC 4346: <citetitle>The Transport Layer Security (TLS)
655
Protocol Version 1.1</citetitle>
659
TLS 1.1 is the protocol implemented by GnuTLS.
665
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
669
The data sent to clients is binary encrypted OpenPGP data.
675
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
680
This is implemented by GnuTLS and used by this server so
681
that OpenPGP keys can be used.
688
<!-- Local Variables: -->
689
<!-- time-stamp-start: "<!ENTITY TIMESTAMP [\"']" -->
690
<!-- time-stamp-end: "[\"']>" -->
691
<!-- time-stamp-format: "%:y-%02m-%02d" -->