36
<holder>Teddy Hogeborn</holder>
37
<holder>Björn Påhlsson</holder>
34
<holder>Teddy Hogeborn & Björn Påhlsson</holder>
39
<xi:include href="legalnotice.xml"/>
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/"/>.
43
62
<refentrytitle>&COMMANDNAME;</refentrytitle>
44
<manvolnum>8</manvolnum>
63
<manvolnum>8mandos</manvolnum>
48
67
<refname><command>&COMMANDNAME;</command></refname>
50
Gives encrypted passwords to authenticated Mandos clients
69
Sends encrypted passwords to authenticated mandos clients
56
75
<command>&COMMANDNAME;</command>
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>
90
<command>&COMMANDNAME;</command>
92
<arg choice="plain"><option>--help</option></arg>
93
<arg choice="plain"><option>-h</option></arg>
97
<command>&COMMANDNAME;</command>
98
<arg choice="plain"><option>--version</option></arg>
101
<command>&COMMANDNAME;</command>
102
<arg choice="plain"><option>--check</option></arg>
76
<arg choice='opt' rep='repeat'>OPTION</arg>
106
80
<refsect1 id="description">
107
81
<title>DESCRIPTION</title>
109
<command>&COMMANDNAME;</command> is a server daemon which
110
handles incoming request for passwords for a pre-defined list of
111
client host computers. The Mandos server uses Zeroconf to
112
announce itself on the local network, and uses TLS to
113
communicate securely with and to authenticate the clients. The
114
Mandos server uses IPv6 to allow Mandos clients to use IPv6
115
link-local addresses, since the clients will probably not have
116
any other addresses configured (see <xref linkend="overview"/>).
117
Any authenticated client is then given the stored pre-encrypted
118
password for that specific client.
122
<refsect1 id="purpose">
123
<title>PURPOSE</title>
125
The purpose of this is to enable <emphasis>remote and unattended
126
rebooting</emphasis> of client host computer with an
127
<emphasis>encrypted root file system</emphasis>. See <xref
128
linkend="overview"/> for details.
132
<refsect1 id="options">
133
<title>OPTIONS</title>
136
<term><option>--help</option></term>
137
<term><option>-h</option></term>
140
Show a help message and exit
146
<term><option>--interface</option>
147
<replaceable>NAME</replaceable></term>
148
<term><option>-i</option>
149
<replaceable>NAME</replaceable></term>
151
<xi:include href="mandos-options.xml" xpointer="interface"/>
156
<term><option>--address
157
<replaceable>ADDRESS</replaceable></option></term>
159
<replaceable>ADDRESS</replaceable></option></term>
161
<xi:include href="mandos-options.xml" xpointer="address"/>
167
<replaceable>PORT</replaceable></option></term>
169
<replaceable>PORT</replaceable></option></term>
171
<xi:include href="mandos-options.xml" xpointer="port"/>
176
<term><option>--check</option></term>
179
Run the server’s self-tests. This includes any unit
186
<term><option>--debug</option></term>
188
<xi:include href="mandos-options.xml" xpointer="debug"/>
193
<term><option>--priority <replaceable>
194
PRIORITY</replaceable></option></term>
196
<xi:include href="mandos-options.xml" xpointer="priority"/>
201
<term><option>--servicename
202
<replaceable>NAME</replaceable></option></term>
204
<xi:include href="mandos-options.xml"
205
xpointer="servicename"/>
210
<term><option>--configdir
211
<replaceable>DIRECTORY</replaceable></option></term>
214
Directory to search for configuration files. Default is
215
<quote><literal>/etc/mandos</literal></quote>. See
216
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
217
<manvolnum>5</manvolnum></citerefentry> and <citerefentry>
218
<refentrytitle>mandos-clients.conf</refentrytitle>
219
<manvolnum>5</manvolnum></citerefentry>.
225
<term><option>--version</option></term>
228
Prints the program version and exit.
235
<refsect1 id="overview">
236
<title>OVERVIEW</title>
237
<xi:include href="overview.xml"/>
239
This program is the server part. It is a normal server program
240
and will run in a normal system environment, not in an initial
241
<acronym>RAM</acronym> disk environment.
245
<refsect1 id="protocol">
246
<title>NETWORK PROTOCOL</title>
248
The Mandos server announces itself as a Zeroconf service of type
249
<quote><literal>_mandos._tcp</literal></quote>. The Mandos
250
client connects to the announced address and port, and sends a
251
line of text where the first whitespace-separated field is the
252
protocol version, which currently is
253
<quote><literal>1</literal></quote>. The client and server then
254
start a TLS protocol handshake with a slight quirk: the Mandos
255
server program acts as a TLS <quote>client</quote> while the
256
connecting Mandos client acts as a TLS <quote>server</quote>.
257
The Mandos client must supply an OpenPGP certificate, and the
258
fingerprint of this certificate is used by the Mandos server to
259
look up (in a list read from <filename>clients.conf</filename>
260
at start time) which binary blob to give the client. No other
261
authentication or authorization is done by the server.
264
<title>Mandos Protocol (Version 1)</title><tgroup cols="3"><thead>
266
<entry>Mandos Client</entry>
267
<entry>Direction</entry>
268
<entry>Mandos Server</entry>
272
<entry>Connect</entry>
273
<entry>-><!-- → --></entry>
276
<entry><quote><literal>1\r\n</literal></quote></entry>
277
<entry>-><!-- → --></entry>
280
<entry>TLS handshake <emphasis>as TLS <quote>server</quote>
282
<entry><-><!-- ⟷ --></entry>
283
<entry>TLS handshake <emphasis>as TLS <quote>client</quote>
287
<entry>OpenPGP public key (part of TLS handshake)</entry>
288
<entry>-><!-- → --></entry>
292
<entry><-<!-- ← --></entry>
293
<entry>Binary blob (client will assume OpenPGP data)</entry>
297
<entry><-<!-- ← --></entry>
300
</tbody></tgroup></table>
303
<refsect1 id="checking">
304
<title>CHECKING</title>
306
The server will, by default, continually check that the clients
307
are still up. If a client has not been confirmed as being up
308
for some time, the client is assumed to be compromised and is no
309
longer eligible to receive the encrypted password. The timeout,
310
checker program, and interval between checks can be configured
311
both globally and per client; see <citerefentry>
312
<refentrytitle>mandos-clients.conf</refentrytitle>
313
<manvolnum>5</manvolnum></citerefentry>.
317
<refsect1 id="logging">
318
<title>LOGGING</title>
320
The server will send log message with various severity levels to
321
<filename>/dev/log</filename>. With the
322
<option>--debug</option> option, it will log even more messages,
323
and also show them on the console.
327
<refsect1 id="exit_status">
328
<title>EXIT STATUS</title>
330
The server will exit with a non-zero exit status only when a
331
critical error is encountered.
335
<refsect1 id="environment">
336
<title>ENVIRONMENT</title>
339
<term><envar>PATH</envar></term>
342
To start the configured checker (see <xref
343
linkend="checking"/>), the server uses
344
<filename>/bin/sh</filename>, which in turn uses
345
<varname>PATH</varname> to search for matching commands if
346
an absolute path is not given. See <citerefentry>
347
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
355
<refsect1 id="files">
358
Use the <option>--configdir</option> option to change where
359
<command>&COMMANDNAME;</command> looks for its configurations
360
files. The default file names are listed here.
364
<term><filename>/etc/mandos/mandos.conf</filename></term>
367
Server-global settings. See
368
<citerefentry><refentrytitle>mandos.conf</refentrytitle>
369
<manvolnum>5</manvolnum></citerefentry> for details.
374
<term><filename>/etc/mandos/clients.conf</filename></term>
377
List of clients and client-specific settings. See
378
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
379
<manvolnum>5</manvolnum></citerefentry> for details.
384
<term><filename>/var/run/mandos.pid</filename></term>
387
The file containing the process id of
388
<command>&COMMANDNAME;</command>.
393
<term><filename>/dev/log</filename></term>
396
The Unix domain socket to where local syslog messages are
402
<term><filename>/bin/sh</filename></term>
405
This is used to start the configured checker command for
406
each client. See <citerefentry>
407
<refentrytitle>mandos-clients.conf</refentrytitle>
408
<manvolnum>5</manvolnum></citerefentry> for details.
418
This server might, on especially fatal errors, emit a Python
419
backtrace. This could be considered a feature.
422
Currently, if a client is declared <quote>invalid</quote> due to
423
having timed out, the server does not record this fact onto
424
permanent storage. This has some security implications, see
425
<xref linkend="clients"/>.
428
There is currently no way of querying the server of the current
429
status of clients, other than analyzing its <systemitem
430
class="service">syslog</systemitem> output.
433
There is no fine-grained control over logging and debug output.
436
Debug mode is conflated with running in the foreground.
439
The console log messages does not show a time stamp.
442
This server does not check the expire time of clients’ OpenPGP
447
<refsect1 id="example">
448
<title>EXAMPLE</title>
451
Normal invocation needs no options:
454
<userinput>&COMMANDNAME;</userinput>
459
Run the server in debug mode, read configuration files from
460
the <filename>~/mandos</filename> directory, and use the
461
Zeroconf service name <quote>Test</quote> to not collide with
462
any other official Mandos server on this host:
466
<!-- do not wrap this line -->
467
<userinput>&COMMANDNAME; --debug --configdir ~/mandos --servicename Test</userinput>
473
Run the server normally, but only listen to one interface and
474
only on the link-local address on that interface:
478
<!-- do not wrap this line -->
479
<userinput>&COMMANDNAME; --interface eth7 --address fe80::aede:48ff:fe71:f6f2</userinput>
485
<refsect1 id="security">
486
<title>SECURITY</title>
487
<refsect2 id="server">
488
<title>SERVER</title>
490
Running this <command>&COMMANDNAME;</command> server program
491
should not in itself present any security risk to the host
492
computer running it. The program switches to a non-root user
496
<refsect2 id="clients">
497
<title>CLIENTS</title>
499
The server only gives out its stored data to clients which
500
does have the OpenPGP key of the stored fingerprint. This is
501
guaranteed by the fact that the client sends its OpenPGP
502
public key in the TLS handshake; this ensures it to be
503
genuine. The server computes the fingerprint of the key
504
itself and looks up the fingerprint in its list of
505
clients. The <filename>clients.conf</filename> file (see
506
<citerefentry><refentrytitle>mandos-clients.conf</refentrytitle>
507
<manvolnum>5</manvolnum></citerefentry>)
508
<emphasis>must</emphasis> be made non-readable by anyone
509
except the user starting the server (usually root).
512
As detailed in <xref linkend="checking"/>, the status of all
513
client computers will continually be checked and be assumed
514
compromised if they are gone for too long.
517
If a client is compromised, its downtime should be duly noted
518
by the server which would therefore declare the client
519
invalid. But if the server was ever restarted, it would
520
re-read its client list from its configuration file and again
521
regard all clients therein as valid, and hence eligible to
522
receive their passwords. Therefore, be careful when
523
restarting servers if it is suspected that a client has, in
524
fact, been compromised by parties who may now be running a
525
fake Mandos client with the keys from the non-encrypted
526
initial <acronym>RAM</acronym> image of the client host. What
527
should be done in that case (if restarting the server program
528
really is necessary) is to stop the server program, edit the
529
configuration file to omit any suspect clients, and restart
533
For more details on client-side security, see
534
<citerefentry><refentrytitle>mandos-client</refentrytitle>
535
<manvolnum>8mandos</manvolnum></citerefentry>.
540
<refsect1 id="see_also">
541
<title>SEE ALSO</title>
544
<refentrytitle>mandos-clients.conf</refentrytitle>
545
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
546
<refentrytitle>mandos.conf</refentrytitle>
547
<manvolnum>5</manvolnum></citerefentry>, <citerefentry>
548
<refentrytitle>mandos-client</refentrytitle>
549
<manvolnum>8mandos</manvolnum></citerefentry>, <citerefentry>
550
<refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum>
556
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
560
Zeroconf is the network protocol standard used by clients
561
for finding this Mandos server on the local network.
567
<ulink url="http://www.avahi.org/">Avahi</ulink>
571
Avahi is the library this server calls to implement
572
Zeroconf service announcements.
578
<ulink url="http://www.gnu.org/software/gnutls/"
583
GnuTLS is the library this server uses to implement TLS for
584
communicating securely with the client, and at the same time
585
confidently get the client’s public OpenPGP key.
591
RFC 4291: <citetitle>IP Version 6 Addressing
592
Architecture</citetitle>
597
<term>Section 2.2: <citetitle>Text Representation of
598
Addresses</citetitle></term>
599
<listitem><para/></listitem>
602
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
603
Address</citetitle></term>
604
<listitem><para/></listitem>
607
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
608
Addresses</citetitle></term>
611
The clients use IPv6 link-local addresses, which are
612
immediately usable since a link-local addresses is
613
automatically assigned to a network interfaces when it
623
RFC 4346: <citetitle>The Transport Layer Security (TLS)
624
Protocol Version 1.1</citetitle>
628
TLS 1.1 is the protocol implemented by GnuTLS.
634
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
638
The data sent to clients is binary encrypted OpenPGP data.
644
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
649
This is implemented by GnuTLS and used by this server so
650
that OpenPGP keys can be used.
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
657
<!-- Local Variables: -->
658
<!-- time-stamp-start: "<!ENTITY TIMESTAMP [\"']" -->
659
<!-- time-stamp-end: "[\"']>" -->
660
<!-- time-stamp-format: "%:y-%02m-%02d" -->