99
128
<command>&COMMANDNAME;</command>
100
129
<group choice="req">
101
<arg choice="plain"><option>--help</option></arg>
102
<arg choice="plain"><option>-?</option></arg>
130
<arg choice='plain'><option>--help</option></arg>
131
<arg choice='plain'><option>-?</option></arg>
106
135
<command>&COMMANDNAME;</command>
107
<arg choice="plain"><option>--usage</option></arg>
136
<arg choice='plain'><option>--usage</option></arg>
110
139
<command>&COMMANDNAME;</command>
111
140
<group choice="req">
112
<arg choice="plain"><option>--version</option></arg>
113
<arg choice="plain"><option>-V</option></arg>
141
<arg choice='plain'><option>--version</option></arg>
142
<arg choice='plain'><option>-V</option></arg>
116
145
</refsynopsisdiv>
118
147
<refsect1 id="description">
119
148
<title>DESCRIPTION</title>
121
<command>&COMMANDNAME;</command> is a client program that
122
communicates with <citerefentry><refentrytitle
123
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>
124
to get a password. It uses IPv6 link-local addresses to get
125
network connectivity, Zeroconf to find servers, and TLS with an
126
OpenPGP key to ensure authenticity and confidentiality. It
127
keeps running, trying all servers on the network, until it
128
receives a satisfactory reply or a TERM signal is received.
131
This program is not meant to be run directly; it is really meant
132
to run as a plugin of the <application>Mandos</application>
133
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
134
<manvolnum>8mandos</manvolnum></citerefentry>, which runs in the
135
initial <acronym>RAM</acronym> disk environment because it is
136
specified as a <quote>keyscript</quote> in the <citerefentry>
137
<refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
138
</citerefentry> file.
142
<refsect1 id="purpose">
143
<title>PURPOSE</title>
145
The purpose of this is to enable <emphasis>remote and unattended
146
rebooting</emphasis> of client host computer with an
147
<emphasis>encrypted root file system</emphasis>. See <xref
148
linkend="overview"/> for details.
150
<command>&COMMANDNAME;</command> is a mandos plugin that works
151
like a client program that through avahi detects mandos servers,
152
sets up a gnutls connect and request a encrypted password. Any
153
passwords given is automaticly decrypted and passed to
152
158
<refsect1 id="options">
153
159
<title>OPTIONS</title>
155
This program is commonly not invoked from the command line; it
156
is normally started by the <application>Mandos</application>
157
plugin runner, see <citerefentry><refentrytitle
158
>plugin-runner</refentrytitle><manvolnum>8mandos</manvolnum>
159
</citerefentry>. Any command line options this program accepts
160
are therefore normally provided by the plugin runner, and not
161
Commonly not invoked as command lines but from configuration
162
file of plugin runner.
166
<term><option>--connect=<replaceable
167
>ADDRESS</replaceable><literal>:</literal><replaceable
168
>PORT</replaceable></option></term>
170
<replaceable>ADDRESS</replaceable><literal>:</literal
171
><replaceable>PORT</replaceable></option></term>
174
Do not use Zeroconf to locate servers. Connect directly
175
to only one specified <application>Mandos</application>
176
server. Note that an IPv6 address has colon characters in
177
it, so the <emphasis>last</emphasis> colon character is
178
assumed to separate the address from the port number.
181
This option is normally only useful for testing and
188
<term><option>--interface=
189
<replaceable>NAME</replaceable></option></term>
191
<replaceable>NAME</replaceable></option></term>
194
Network interface that will be brought up and scanned for
195
Mandos servers to connect to. The default it
196
<quote><literal>eth0</literal></quote>.
199
If the <option>--connect</option> option is used, this
200
specifies the interface to use to connect to the address
207
<term><option>--pubkey=<replaceable
208
>FILE</replaceable></option></term>
210
<replaceable>FILE</replaceable></option></term>
213
OpenPGP public key file name. The default name is
214
<quote><filename>/conf/conf.d/mandos/pubkey.txt</filename
221
<term><option>--seckey=<replaceable
222
>FILE</replaceable></option></term>
224
<replaceable>FILE</replaceable></option></term>
227
OpenPGP secret key file name. The default name is
228
<quote><filename>/conf/conf.d/mandos/seckey.txt</filename
235
<term><option>--priority=<replaceable
236
>STRING</replaceable></option></term>
238
<xi:include href="../mandos-options.xml"
239
xpointer="priority"/>
244
<term><option>--dh-bits=<replaceable
245
>BITS</replaceable></option></term>
248
Sets the number of bits to use for the prime number in the
249
TLS Diffie-Hellman key exchange. Default is 1024.
255
<term><option>--debug</option></term>
258
Enable debug mode. This will enable a lot of output to
259
standard error about what the program is doing. The
260
program will still perform all other functions normally.
263
It will also enable debug mode in the Avahi and GnuTLS
264
libraries, making them print large amounts of debugging
271
<term><option>--help</option></term>
272
<term><option>-?</option></term>
275
Gives a help message about options and their meanings.
281
<term><option>--usage</option></term>
284
Gives a short usage message.
290
<term><option>--version</option></term>
291
<term><option>-V</option></term>
294
Prints the program version.
167
<term><literal>-c</literal>, <literal>--connect=<replaceable>
168
IP</replaceable></literal></term>
171
Connect directly to a specified mandos server
177
<term><literal>-d</literal>, <literal>--keydir=<replaceable>
178
KEYDIR</replaceable></literal></term>
181
Directory where the openpgp keyring is
187
<term><literal>-i</literal>, <literal>--interface=
188
<replaceable>INTERFACE</replaceable></literal></term>
191
Interface that Avahi will conntect through
197
<term><literal>-p</literal>, <literal>--pubkey=<replaceable>
198
PUBKEY</replaceable></literal></term>
201
Public openpgp key for gnutls authentication
207
<term><literal>-s</literal>, <literal>--seckey=<replaceable>
208
SECKEY</replaceable></literal></term>
211
Secret openpgp key for gnutls authentication
217
<term><literal>--priority=<replaceable>PRIORITY</replaceable>
227
<term><literal>--dh-bits=<replaceable>BITS</replaceable>
231
dh-bits to use in gnutls communication
237
<term><literal>--debug</literal></term>
246
<term><literal>-?</literal>, <literal>--help</literal></term>
255
<term><literal>--usage</literal></term>
258
Gives a short usage message
264
<term><literal>-V</literal>, <literal>--version</literal></term>
267
Prints the program version
301
<refsect1 id="overview">
302
<title>OVERVIEW</title>
303
<xi:include href="../overview.xml"/>
305
This program is the client part. It is a plugin started by
306
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
307
<manvolnum>8mandos</manvolnum></citerefentry> which will run in
308
an initial <acronym>RAM</acronym> disk environment.
311
This program could, theoretically, be used as a keyscript in
312
<filename>/etc/crypttab</filename>, but it would then be
313
impossible to enter a password for the encrypted root disk at
314
the console, since this program does not read from the console
315
at all. This is why a separate plugin runner (<citerefentry>
316
<refentrytitle>plugin-runner</refentrytitle>
317
<manvolnum>8mandos</manvolnum></citerefentry>) is used to run
318
both this program and others in in parallel,
319
<emphasis>one</emphasis> of which will prompt for passwords on
324
274
<refsect1 id="exit_status">
325
275
<title>EXIT STATUS</title>
327
This program will exit with a successful (zero) exit status if a
328
server could be found and the password received from it could be
329
successfully decrypted and output on standard output. The
330
program will exit with a non-zero exit status only if a critical
331
error occurs. Otherwise, it will forever connect to new
332
<application>Mandos</application> servers as they appear, trying
333
to get a decryptable password and print it.
337
280
<refsect1 id="environment">
338
281
<title>ENVIRONMENT</title>
340
This program does not use any environment variables, not even
341
the ones provided by <citerefentry><refentrytitle
342
>cryptsetup</refentrytitle><manvolnum>8</manvolnum>
347
286
<refsect1 id="file">
348
287
<title>FILES</title>
351
<term><filename>/conf/conf.d/mandos/pubkey.txt</filename
353
<term><filename>/conf/conf.d/mandos/seckey.txt</filename
357
OpenPGP public and private key files, in <quote>ASCII
358
Armor</quote> format. These are the default file names,
359
they can be changed with the <option>--pubkey</option> and
360
<option>--seckey</option> options.
367
<!-- <refsect1 id="bugs"> -->
368
<!-- <title>BUGS</title> -->
373
298
<refsect1 id="example">
374
299
<title>EXAMPLE</title>
376
Note that normally, command line options will not be given
377
directly, but via options for the Mandos <citerefentry
378
><refentrytitle>plugin-runner</refentrytitle>
379
<manvolnum>8mandos</manvolnum></citerefentry>.
383
Normal invocation needs no options, if the network interface
384
is <quote>eth0</quote>:
387
<userinput>&COMMANDNAME;</userinput>
392
Search for Mandos servers (and connect to them) using another
396
<!-- do not wrap this line -->
397
<userinput>&COMMANDNAME; --interface eth1</userinput>
402
Run in debug mode, and use a custom key:
406
<!-- do not wrap this line -->
407
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt</userinput>
413
Run in debug mode, with a custom key, and do not use Zeroconf
414
to locate a server; connect directly to the IPv6 address
415
<quote><systemitem class="ipaddress"
416
>2001:db8:f983:bd0b:30de:ae4a:71f2:f672</systemitem></quote>,
417
port 4711, using interface eth2:
421
<!-- do not wrap this line -->
422
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt --connect 2001:db8:f983:bd0b:30de:ae4a:71f2:f672:4711 --interface eth2</userinput>
428
304
<refsect1 id="security">
429
305
<title>SECURITY</title>
431
This program is set-uid to root, but will switch back to the
432
original (and presumably non-privileged) user and group after
433
bringing up the network interface.
436
To use this program for its intended purpose (see <xref
437
linkend="purpose"/>), the password for the root file system will
438
have to be given out to be stored in a server computer, after
439
having been encrypted using an OpenPGP key. This encrypted data
440
which will be stored in a server can only be decrypted by the
441
OpenPGP key, and the data will only be given out to those
442
clients who can prove they actually have that key. This key,
443
however, is stored unencrypted on the client side in its initial
444
<acronym>RAM</acronym> disk image file system. This is normally
445
readable by all, but this is normally fixed during installation
446
of this program; file permissions are set so that no-one is able
450
The only remaining weak point is that someone with physical
451
access to the client hard drive might turn off the client
452
computer, read the OpenPGP keys directly from the hard drive,
453
and communicate with the server. To safeguard against this, the
454
server is supposed to notice the client disappearing and stop
455
giving out the encrypted data. Therefore, it is important to
456
set the timeout and checker interval values tightly on the
457
server. See <citerefentry><refentrytitle
458
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
461
It will also help if the checker program on the server is
462
configured to request something from the client which can not be
463
spoofed by someone else on the network, unlike unencrypted
464
<acronym>ICMP</acronym> echo (<quote>ping</quote>) replies.
467
<emphasis>Note</emphasis>: This makes it completely insecure to
468
have <application >Mandos</application> clients which dual-boot
469
to another operating system which is <emphasis>not</emphasis>
470
trusted to keep the initial <acronym>RAM</acronym> disk image
475
310
<refsect1 id="see_also">
476
311
<title>SEE ALSO</title>
478
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
479
<manvolnum>8</manvolnum></citerefentry>,
480
<citerefentry><refentrytitle>crypttab</refentrytitle>
481
<manvolnum>5</manvolnum></citerefentry>,
482
313
<citerefentry><refentrytitle>mandos</refentrytitle>
483
314
<manvolnum>8</manvolnum></citerefentry>,
484
315
<citerefentry><refentrytitle>password-prompt</refentrytitle>
486
317
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
487
318
<manvolnum>8mandos</manvolnum></citerefentry>
492
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
496
Zeroconf is the network protocol standard used for finding
497
Mandos servers on the local network.
503
<ulink url="http://www.avahi.org/">Avahi</ulink>
507
Avahi is the library this program calls to find Zeroconf
514
<ulink url="http://www.gnu.org/software/gnutls/"
519
GnuTLS is the library this client uses to implement TLS for
520
communicating securely with the server, and at the same time
521
send the public OpenPGP key to the server.
527
<ulink url="http://www.gnupg.org/related_software/gpgme/"
532
GPGME is the library used to decrypt the OpenPGP data sent
539
RFC 4291: <citetitle>IP Version 6 Addressing
540
Architecture</citetitle>
545
<term>Section 2.2: <citetitle>Text Representation of
546
Addresses</citetitle></term>
547
<listitem><para/></listitem>
550
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
551
Address</citetitle></term>
552
<listitem><para/></listitem>
555
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
556
Addresses</citetitle></term>
559
This client uses IPv6 link-local addresses, which are
560
immediately usable since a link-local addresses is
561
automatically assigned to a network interfaces when it
571
RFC 4346: <citetitle>The Transport Layer Security (TLS)
572
Protocol Version 1.1</citetitle>
576
TLS 1.1 is the protocol implemented by GnuTLS.
582
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
586
The data received from the server is binary encrypted
593
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
598
This is implemented by GnuTLS and used by this program so
599
that OpenPGP keys can be used.
322
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
326
<ulink url="http://www.avahi.org/">Avahi</ulink>
331
url="http://www.gnu.org/software/gnutls/">GnuTLS</ulink>
336
url="http://www.gnupg.org/related_software/gpgme/">
341
<citation>RFC 4880: <citetitle>OpenPGP Message
342
Format</citetitle></citation>
346
<citation>RFC 5081: <citetitle>Using OpenPGP Keys for
347
Transport Layer Security</citetitle></citation>
351
<citation>RFC 4291: <citetitle>IP Version 6 Addressing
352
Architecture</citetitle>, section 2.5.6, Link-Local IPv6
353
Unicast Addresses</citation>
607
359
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