34
<holder>Teddy Hogeborn & Björn Påhlsson</holder>
36
<holder>Teddy Hogeborn</holder>
37
<holder>Björn Påhlsson</holder>
38
This manual page is free software: you can redistribute it
39
and/or modify it under the terms of the GNU General Public
40
License as published by the Free Software Foundation,
41
either version 3 of the License, or (at your option) any
46
This manual page is distributed in the hope that it will
47
be useful, but WITHOUT ANY WARRANTY; without even the
48
implied warranty of MERCHANTABILITY or FITNESS FOR A
49
PARTICULAR PURPOSE. See the GNU General Public License
54
You should have received a copy of the GNU General Public
55
License along with this program; If not, see
56
<ulink url="http://www.gnu.org/licenses/"/>.
39
<xi:include href="legalnotice.xml"/>
62
43
<refentrytitle>&COMMANDNAME;</refentrytitle>
63
<manvolnum>8mandos</manvolnum>
44
<manvolnum>8</manvolnum>
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' rep='repeat'>OPTION</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>
80
110
<refsect1 id="description">
81
111
<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
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. (Manual
331
intervention is required to re-enable a client.) The timeout,
332
checker program, and interval between checks can be configured
333
both globally and per client; see <citerefentry>
334
<refentrytitle>mandos-clients.conf</refentrytitle>
335
<manvolnum>5</manvolnum></citerefentry>. A client successfully
336
receiving its password will also be treated as a successful
341
<refsect1 id="logging">
342
<title>LOGGING</title>
344
The server will send log message with various severity levels to
345
<filename>/dev/log</filename>. With the
346
<option>--debug</option> option, it will log even more messages,
347
and also show them on the console.
351
<refsect1 id="dbus_interface">
352
<title>D-BUS INTERFACE</title>
354
The server will by default provide a D-Bus system bus interface.
355
This interface will only be accessible by the root user or a
356
Mandos-specific user, if such a user exists. For documentation
357
of the D-Bus API, see the file <filename>DBUS-API</filename>.
361
<refsect1 id="exit_status">
362
<title>EXIT STATUS</title>
364
The server will exit with a non-zero exit status only when a
365
critical error is encountered.
369
<refsect1 id="environment">
370
<title>ENVIRONMENT</title>
373
<term><envar>PATH</envar></term>
376
To start the configured checker (see <xref
377
linkend="checking"/>), the server uses
378
<filename>/bin/sh</filename>, which in turn uses
379
<varname>PATH</varname> to search for matching commands if
380
an absolute path is not given. See <citerefentry>
381
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
389
<refsect1 id="files">
392
Use the <option>--configdir</option> option to change where
393
<command>&COMMANDNAME;</command> looks for its configurations
394
files. The default file names are listed here.
398
<term><filename>/etc/mandos/mandos.conf</filename></term>
401
Server-global settings. See
402
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
403
<manvolnum>5</manvolnum></citerefentry> for details.
408
<term><filename>/etc/mandos/clients.conf</filename></term>
411
List of clients and client-specific settings. See
412
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
413
<manvolnum>5</manvolnum></citerefentry> for details.
418
<term><filename>/var/run/mandos.pid</filename></term>
421
The file containing the process id of
422
<command>&COMMANDNAME;</command>.
427
<term><filename>/dev/log</filename></term>
430
The Unix domain socket to where local syslog messages are
436
<term><filename>/bin/sh</filename></term>
439
This is used to start the configured checker command for
440
each client. See <citerefentry>
441
<refentrytitle>mandos-clients.conf</refentrytitle>
442
<manvolnum>5</manvolnum></citerefentry> for details.
452
This server might, on especially fatal errors, emit a Python
453
backtrace. This could be considered a feature.
456
Currently, if a client is disabled due to having timed out, the
457
server does not record this fact onto permanent storage. This
458
has some security implications, see <xref linkend="clients"/>.
461
There is no fine-grained control over logging and debug output.
464
Debug mode is conflated with running in the foreground.
467
The console log messages do not show a time stamp.
470
This server does not check the expire time of clients’ OpenPGP
475
<refsect1 id="example">
476
<title>EXAMPLE</title>
479
Normal invocation needs no options:
482
<userinput>&COMMANDNAME;</userinput>
487
Run the server in debug mode, read configuration files from
488
the <filename>~/mandos</filename> directory, and use the
489
Zeroconf service name <quote>Test</quote> to not collide with
490
any other official Mandos server on this host:
494
<!-- do not wrap this line -->
495
<userinput>&COMMANDNAME; --debug --configdir ~/mandos --servicename Test</userinput>
501
Run the server normally, but only listen to one interface and
502
only on the link-local address on that interface:
506
<!-- do not wrap this line -->
507
<userinput>&COMMANDNAME; --interface eth7 --address fe80::aede:48ff:fe71:f6f2</userinput>
513
<refsect1 id="security">
514
<title>SECURITY</title>
515
<refsect2 id="server">
516
<title>SERVER</title>
518
Running this <command>&COMMANDNAME;</command> server program
519
should not in itself present any security risk to the host
520
computer running it. The program switches to a non-root user
524
<refsect2 id="clients">
525
<title>CLIENTS</title>
527
The server only gives out its stored data to clients which
528
does have the OpenPGP key of the stored fingerprint. This is
529
guaranteed by the fact that the client sends its OpenPGP
530
public key in the TLS handshake; this ensures it to be
531
genuine. The server computes the fingerprint of the key
532
itself and looks up the fingerprint in its list of
533
clients. The <filename>clients.conf</filename> file (see
534
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
535
<manvolnum>5</manvolnum></citerefentry>)
536
<emphasis>must</emphasis> be made non-readable by anyone
537
except the user starting the server (usually root).
540
As detailed in <xref linkend="checking"/>, the status of all
541
client computers will continually be checked and be assumed
542
compromised if they are gone for too long.
545
If a client is compromised, its downtime should be duly noted
546
by the server which would therefore disable the client. But
547
if the server was ever restarted, it would re-read its client
548
list from its configuration file and again regard all clients
549
therein as enabled, and hence eligible to receive their
550
passwords. Therefore, be careful when restarting servers if
551
it is suspected that a client has, in fact, been compromised
552
by parties who may now be running a fake Mandos client with
553
the keys from the non-encrypted initial <acronym>RAM</acronym>
554
image of the client host. What should be done in that case
555
(if restarting the server program really is necessary) is to
556
stop the server program, edit the configuration file to omit
557
any suspect clients, and restart the server program.
560
For more details on client-side security, see
561
<citerefentry><refentrytitle>mandos-client</refentrytitle>
562
<manvolnum>8mandos</manvolnum></citerefentry>.
567
<refsect1 id="see_also">
568
<title>SEE ALSO</title>
571
<refentrytitle>mandos-clients.conf</refentrytitle>
572
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
573
<refentrytitle>mandos.conf</refentrytitle>
574
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
575
<refentrytitle>mandos-client</refentrytitle>
576
<manvolnum>8mandos</manvolnum></citerefentry>, <citerefentry>
577
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
583
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
587
Zeroconf is the network protocol standard used by clients
588
for finding this Mandos server on the local network.
594
<ulink url="http://www.avahi.org/">Avahi</ulink>
598
Avahi is the library this server calls to implement
599
Zeroconf service announcements.
605
<ulink url="http://www.gnu.org/software/gnutls/"
610
GnuTLS is the library this server uses to implement TLS for
611
communicating securely with the client, and at the same time
612
confidently get the client’s public OpenPGP key.
618
RFC 4291: <citetitle>IP Version 6 Addressing
619
Architecture</citetitle>
624
<term>Section 2.2: <citetitle>Text Representation of
625
Addresses</citetitle></term>
626
<listitem><para/></listitem>
629
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
630
Address</citetitle></term>
631
<listitem><para/></listitem>
634
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
635
Addresses</citetitle></term>
638
The clients use IPv6 link-local addresses, which are
639
immediately usable since a link-local addresses is
640
automatically assigned to a network interfaces when it
650
RFC 4346: <citetitle>The Transport Layer Security (TLS)
651
Protocol Version 1.1</citetitle>
655
TLS 1.1 is the protocol implemented by GnuTLS.
661
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
665
The data sent to clients is binary encrypted OpenPGP data.
671
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
676
This is implemented by GnuTLS and used by this server so
677
that OpenPGP keys can be used.
684
<!-- Local Variables: -->
685
<!-- time-stamp-start: "<!ENTITY TIMESTAMP [\"']" -->
686
<!-- time-stamp-end: "[\"']>" -->
687
<!-- time-stamp-format: "%:y-%02m-%02d" -->