47
67
<refname><command>&COMMANDNAME;</command></refname>
49
Gives encrypted passwords to authenticated Mandos clients
69
Sends encrypted passwords to authenticated mandos clients
55
75
<command>&COMMANDNAME;</command>
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>
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'>--version</arg>
93
<command>&COMMANDNAME;</command>
94
<arg choice='plain'>--check</arg>
107
98
<refsect1 id="description">
108
99
<title>DESCRIPTION</title>
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_interface"/>.
246
<refsect1 id="overview">
247
<title>OVERVIEW</title>
248
<xi:include href="overview.xml"/>
250
This program is the server part. It is a normal server program
251
and will run in a normal system environment, not in an initial
252
<acronym>RAM</acronym> disk environment.
256
<refsect1 id="protocol">
257
<title>NETWORK PROTOCOL</title>
259
The Mandos server announces itself as a Zeroconf service of type
260
<quote><literal>_mandos._tcp</literal></quote>. The Mandos
261
client connects to the announced address and port, and sends a
262
line of text where the first whitespace-separated field is the
263
protocol version, which currently is
264
<quote><literal>1</literal></quote>. The client and server then
265
start a TLS protocol handshake with a slight quirk: the Mandos
266
server program acts as a TLS <quote>client</quote> while the
267
connecting Mandos client acts as a TLS <quote>server</quote>.
268
The Mandos client must supply an OpenPGP certificate, and the
269
fingerprint of this certificate is used by the Mandos server to
270
look up (in a list read from <filename>clients.conf</filename>
271
at start time) which binary blob to give the client. No other
272
authentication or authorization is done by the server.
275
<title>Mandos Protocol (Version 1)</title><tgroup cols="3"><thead>
277
<entry>Mandos Client</entry>
278
<entry>Direction</entry>
279
<entry>Mandos Server</entry>
283
<entry>Connect</entry>
284
<entry>-><!-- → --></entry>
287
<entry><quote><literal>1\r\n</literal></quote></entry>
288
<entry>-><!-- → --></entry>
291
<entry>TLS handshake <emphasis>as TLS <quote>server</quote>
293
<entry><-><!-- ⟷ --></entry>
294
<entry>TLS handshake <emphasis>as TLS <quote>client</quote>
298
<entry>OpenPGP public key (part of TLS handshake)</entry>
299
<entry>-><!-- → --></entry>
303
<entry><-<!-- ← --></entry>
304
<entry>Binary blob (client will assume OpenPGP data)</entry>
308
<entry><-<!-- ← --></entry>
311
</tbody></tgroup></table>
314
<refsect1 id="checking">
315
<title>CHECKING</title>
317
The server will, by default, continually check that the clients
318
are still up. If a client has not been confirmed as being up
319
for some time, the client is assumed to be compromised and is no
320
longer eligible to receive the encrypted password. The timeout,
321
checker program, and interval between checks can be configured
322
both globally and per client; see <citerefentry>
323
<refentrytitle>mandos-clients.conf</refentrytitle>
324
<manvolnum>5</manvolnum></citerefentry>.
328
<refsect1 id="logging">
329
<title>LOGGING</title>
331
The server will send log message with various severity levels to
332
<filename>/dev/log</filename>. With the
333
<option>--debug</option> option, it will log even more messages,
334
and also show them on the console.
338
<refsect1 id="dbus_interface">
339
<title>D-BUS INTERFACE</title>
341
The server will by default provide a D-Bus system bus interface.
342
This interface will only be accessible by the root user or a
343
Mandos-specific user, if such a user exists.
348
<refsect1 id="exit_status">
349
<title>EXIT STATUS</title>
351
The server will exit with a non-zero exit status only when a
352
critical error is encountered.
356
<refsect1 id="environment">
357
<title>ENVIRONMENT</title>
360
<term><envar>PATH</envar></term>
363
To start the configured checker (see <xref
364
linkend="checking"/>), the server uses
365
<filename>/bin/sh</filename>, which in turn uses
366
<varname>PATH</varname> to search for matching commands if
367
an absolute path is not given. See <citerefentry>
368
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
376
<refsect1 id="files">
379
Use the <option>--configdir</option> option to change where
380
<command>&COMMANDNAME;</command> looks for its configurations
381
files. The default file names are listed here.
385
<term><filename>/etc/mandos/mandos.conf</filename></term>
388
Server-global settings. See
389
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
390
<manvolnum>5</manvolnum></citerefentry> for details.
395
<term><filename>/etc/mandos/clients.conf</filename></term>
398
List of clients and client-specific settings. See
399
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
400
<manvolnum>5</manvolnum></citerefentry> for details.
405
<term><filename>/var/run/mandos.pid</filename></term>
408
The file containing the process id of
409
<command>&COMMANDNAME;</command>.
414
<term><filename>/dev/log</filename></term>
417
The Unix domain socket to where local syslog messages are
423
<term><filename>/bin/sh</filename></term>
426
This is used to start the configured checker command for
427
each client. See <citerefentry>
428
<refentrytitle>mandos-clients.conf</refentrytitle>
429
<manvolnum>5</manvolnum></citerefentry> for details.
439
This server might, on especially fatal errors, emit a Python
440
backtrace. This could be considered a feature.
443
Currently, if a client is declared <quote>invalid</quote> due to
444
having timed out, the server does not record this fact onto
445
permanent storage. This has some security implications, see
446
<xref linkend="clients"/>.
449
There is currently no way of querying the server of the current
450
status of clients, other than analyzing its <systemitem
451
class="service">syslog</systemitem> output.
454
There is no fine-grained control over logging and debug output.
457
Debug mode is conflated with running in the foreground.
460
The console log messages does not show a time stamp.
463
This server does not check the expire time of clients’ OpenPGP
468
<refsect1 id="example">
469
<title>EXAMPLE</title>
472
Normal invocation needs no options:
475
<userinput>&COMMANDNAME;</userinput>
480
Run the server in debug mode, read configuration files from
481
the <filename>~/mandos</filename> directory, and use the
482
Zeroconf service name <quote>Test</quote> to not collide with
483
any other official Mandos server on this host:
487
<!-- do not wrap this line -->
488
<userinput>&COMMANDNAME; --debug --configdir ~/mandos --servicename Test</userinput>
494
Run the server normally, but only listen to one interface and
495
only on the link-local address on that interface:
499
<!-- do not wrap this line -->
500
<userinput>&COMMANDNAME; --interface eth7 --address fe80::aede:48ff:fe71:f6f2</userinput>
506
<refsect1 id="security">
507
<title>SECURITY</title>
508
<refsect2 id="server">
509
<title>SERVER</title>
511
Running this <command>&COMMANDNAME;</command> server program
512
should not in itself present any security risk to the host
513
computer running it. The program switches to a non-root user
517
<refsect2 id="clients">
518
<title>CLIENTS</title>
520
The server only gives out its stored data to clients which
521
does have the OpenPGP key of the stored fingerprint. This is
522
guaranteed by the fact that the client sends its OpenPGP
523
public key in the TLS handshake; this ensures it to be
524
genuine. The server computes the fingerprint of the key
525
itself and looks up the fingerprint in its list of
526
clients. The <filename>clients.conf</filename> file (see
527
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
528
<manvolnum>5</manvolnum></citerefentry>)
529
<emphasis>must</emphasis> be made non-readable by anyone
530
except the user starting the server (usually root).
533
As detailed in <xref linkend="checking"/>, the status of all
534
client computers will continually be checked and be assumed
535
compromised if they are gone for too long.
538
If a client is compromised, its downtime should be duly noted
539
by the server which would therefore declare the client
540
invalid. But if the server was ever restarted, it would
541
re-read its client list from its configuration file and again
542
regard all clients therein as valid, and hence eligible to
543
receive their passwords. Therefore, be careful when
544
restarting servers if it is suspected that a client has, in
545
fact, been compromised by parties who may now be running a
546
fake Mandos client with the keys from the non-encrypted
547
initial <acronym>RAM</acronym> image of the client host. What
548
should be done in that case (if restarting the server program
549
really is necessary) is to stop the server program, edit the
550
configuration file to omit any suspect clients, and restart
554
For more details on client-side security, see
555
<citerefentry><refentrytitle>mandos-client</refentrytitle>
556
<manvolnum>8mandos</manvolnum></citerefentry>.
561
<refsect1 id="see_also">
562
<title>SEE ALSO</title>
565
<refentrytitle>mandos-clients.conf</refentrytitle>
566
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
567
<refentrytitle>mandos.conf</refentrytitle>
568
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
569
<refentrytitle>mandos-client</refentrytitle>
570
<manvolnum>8mandos</manvolnum></citerefentry>, <citerefentry>
571
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
577
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
581
Zeroconf is the network protocol standard used by clients
582
for finding this Mandos server on the local network.
588
<ulink url="http://www.avahi.org/">Avahi</ulink>
592
Avahi is the library this server calls to implement
593
Zeroconf service announcements.
599
<ulink url="http://www.gnu.org/software/gnutls/"
604
GnuTLS is the library this server uses to implement TLS for
605
communicating securely with the client, and at the same time
606
confidently get the client’s public OpenPGP key.
612
RFC 4291: <citetitle>IP Version 6 Addressing
613
Architecture</citetitle>
618
<term>Section 2.2: <citetitle>Text Representation of
619
Addresses</citetitle></term>
620
<listitem><para/></listitem>
623
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
624
Address</citetitle></term>
625
<listitem><para/></listitem>
628
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
629
Addresses</citetitle></term>
632
The clients use IPv6 link-local addresses, which are
633
immediately usable since a link-local addresses is
634
automatically assigned to a network interfaces when it
644
RFC 4346: <citetitle>The Transport Layer Security (TLS)
645
Protocol Version 1.1</citetitle>
649
TLS 1.1 is the protocol implemented by GnuTLS.
655
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
659
The data sent to clients is binary encrypted OpenPGP data.
665
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
670
This is implemented by GnuTLS and used by this server so
671
that OpenPGP keys can be used.
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
199
<term><literal>--version</literal></term>
202
Prints the program version
678
<!-- Local Variables: -->
679
<!-- time-stamp-start: "<!ENTITY TIMESTAMP [\"']" -->
680
<!-- time-stamp-end: "[\"']>" -->
681
<!-- time-stamp-format: "%:y-%02m-%02d" -->