67
49
<refname><command>&COMMANDNAME;</command></refname>
51
Client for <application>Mandos</application>
75
57
<command>&COMMANDNAME;</command>
76
<arg choice='opt' rep='repeat'>OPTION</arg>
59
<arg choice="plain"><option>--connect
60
<replaceable>ADDRESS</replaceable><literal>:</literal
61
><replaceable>PORT</replaceable></option></arg>
62
<arg choice="plain"><option>-c
63
<replaceable>ADDRESS</replaceable><literal>:</literal
64
><replaceable>PORT</replaceable></option></arg>
68
<arg choice="plain"><option>--interface
69
<replaceable>NAME</replaceable></option></arg>
70
<arg choice="plain"><option>-i
71
<replaceable>NAME</replaceable></option></arg>
75
<arg choice="plain"><option>--pubkey
76
<replaceable>FILE</replaceable></option></arg>
77
<arg choice="plain"><option>-p
78
<replaceable>FILE</replaceable></option></arg>
82
<arg choice="plain"><option>--seckey
83
<replaceable>FILE</replaceable></option></arg>
84
<arg choice="plain"><option>-s
85
<replaceable>FILE</replaceable></option></arg>
89
<option>--priority <replaceable>STRING</replaceable></option>
93
<option>--dh-bits <replaceable>BITS</replaceable></option>
97
<option>--delay <replaceable>SECONDS</replaceable></option>
101
<option>--retry <replaceable>SECONDS</replaceable></option>
105
<option>--network-hook-dir<replaceable>DIR</replaceable></option>
109
<option>--debug</option>
113
<command>&COMMANDNAME;</command>
115
<arg choice="plain"><option>--help</option></arg>
116
<arg choice="plain"><option>-?</option></arg>
120
<command>&COMMANDNAME;</command>
121
<arg choice="plain"><option>--usage</option></arg>
124
<command>&COMMANDNAME;</command>
126
<arg choice="plain"><option>--version</option></arg>
127
<arg choice="plain"><option>-V</option></arg>
80
132
<refsect1 id="description">
81
133
<title>DESCRIPTION</title>
83
<command>&COMMANDNAME;</command> is a mandos plugin that works
84
like a client program that through avahi detects mandos servers,
85
sets up a gnutls connect and request a encrypted password. Any
86
passwords given is automaticly decrypted and passed to
92
<term><literal>-c</literal>, <literal>--connect=<replaceable>
93
IP</replaceable></literal></term>
96
Connect directly to a sepcified mandos server
102
<term><literal>-d</literal>, <literal>--keydir=<replaceable>
103
KEYDIR</replaceable></literal></term>
106
Directory where the openpgp keyring is
112
<term><literal>-i</literal>, <literal>--interface=
113
<replaceable>INTERFACE</replaceable></literal></term>
116
Interface that Avahi will conntect through
122
<term><literal>-p</literal>, <literal>--pubkey=<replaceable>
123
PUBKEY</replaceable></literal></term>
126
Public openpgp key for gnutls authentication
132
<term><literal>-s</literal>, <literal>--seckey=<replaceable>
133
SECKEY</replaceable></literal></term>
136
Secret openpgp key for gnutls authentication
142
<term><literal>--priority=<replaceable>PRIORITY</replaceable>
152
<term><literal>--dh-bits=<replaceable>BITS</replaceable>
156
dh-bits to use in gnutls communication
162
<term><literal>--debug</literal></term>
171
<term><literal>-?</literal>, <literal>--help</literal></term>
180
<term><literal>--usage</literal></term>
183
Gives a short usage message
189
<term><literal>-V</literal>, <literal>--version</literal></term>
192
Prints the program version
135
<command>&COMMANDNAME;</command> is a client program that
136
communicates with <citerefentry><refentrytitle
137
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>
138
to get a password. In slightly more detail, this client program
139
brings up a network interface, uses the interface’s IPv6
140
link-local address to get network connectivity, uses Zeroconf to
141
find servers on the local network, and communicates with servers
142
using TLS with an OpenPGP key to ensure authenticity and
143
confidentiality. This client program keeps running, trying all
144
servers on the network, until it receives a satisfactory reply
145
or a TERM signal. After all servers have been tried, all
146
servers are periodically retried. If no servers are found it
147
will wait indefinitely for new servers to appear.
150
This program is not meant to be run directly; it is really meant
151
to run as a plugin of the <application>Mandos</application>
152
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
153
<manvolnum>8mandos</manvolnum></citerefentry>, which runs in the
154
initial <acronym>RAM</acronym> disk environment because it is
155
specified as a <quote>keyscript</quote> in the <citerefentry>
156
<refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
157
</citerefentry> file.
161
<refsect1 id="purpose">
162
<title>PURPOSE</title>
164
The purpose of this is to enable <emphasis>remote and unattended
165
rebooting</emphasis> of client host computer with an
166
<emphasis>encrypted root file system</emphasis>. See <xref
167
linkend="overview"/> for details.
171
<refsect1 id="options">
172
<title>OPTIONS</title>
174
This program is commonly not invoked from the command line; it
175
is normally started by the <application>Mandos</application>
176
plugin runner, see <citerefentry><refentrytitle
177
>plugin-runner</refentrytitle><manvolnum>8mandos</manvolnum>
178
</citerefentry>. Any command line options this program accepts
179
are therefore normally provided by the plugin runner, and not
185
<term><option>--connect=<replaceable
186
>ADDRESS</replaceable><literal>:</literal><replaceable
187
>PORT</replaceable></option></term>
189
<replaceable>ADDRESS</replaceable><literal>:</literal
190
><replaceable>PORT</replaceable></option></term>
193
Do not use Zeroconf to locate servers. Connect directly
194
to only one specified <application>Mandos</application>
195
server. Note that an IPv6 address has colon characters in
196
it, so the <emphasis>last</emphasis> colon character is
197
assumed to separate the address from the port number.
200
This option is normally only useful for testing and
207
<term><option>--interface=<replaceable
208
>NAME</replaceable></option></term>
210
<replaceable>NAME</replaceable></option></term>
213
Network interface that will be brought up and scanned for
214
Mandos servers to connect to. The default is the empty
215
string, which will automatically choose an appropriate
219
If the <option>--connect</option> option is used, this
220
specifies the interface to use to connect to the address
224
Note that since this program will normally run in the
225
initial RAM disk environment, the interface must be an
226
interface which exists at that stage. Thus, the interface
227
can not be a pseudo-interface such as <quote>br0</quote>
228
or <quote>tun0</quote>; such interfaces will not exist
229
until much later in the boot process, and can not be used
233
<replaceable>NAME</replaceable> can be the string
234
<quote><literal>none</literal></quote>; this will not use
235
any specific interface, and will not bring up an interface
236
on startup. This is not recommended, and only meant for
243
<term><option>--pubkey=<replaceable
244
>FILE</replaceable></option></term>
246
<replaceable>FILE</replaceable></option></term>
249
OpenPGP public key file name. The default name is
250
<quote><filename>/conf/conf.d/mandos/pubkey.txt</filename
257
<term><option>--seckey=<replaceable
258
>FILE</replaceable></option></term>
260
<replaceable>FILE</replaceable></option></term>
263
OpenPGP secret key file name. The default name is
264
<quote><filename>/conf/conf.d/mandos/seckey.txt</filename
271
<term><option>--priority=<replaceable
272
>STRING</replaceable></option></term>
274
<xi:include href="../mandos-options.xml"
275
xpointer="priority"/>
280
<term><option>--dh-bits=<replaceable
281
>BITS</replaceable></option></term>
284
Sets the number of bits to use for the prime number in the
285
TLS Diffie-Hellman key exchange. Default is 1024.
291
<term><option>--delay=<replaceable
292
>SECONDS</replaceable></option></term>
295
After bringing the network interface up, the program waits
296
for the interface to arrive in a <quote>running</quote>
297
state before proceeding. During this time, the kernel log
298
level will be lowered to reduce clutter on the system
299
console, alleviating any other plugins which might be
300
using the system console. This option sets the upper
301
limit of seconds to wait. The default is 2.5 seconds.
307
<term><option>--retry=<replaceable
308
>SECONDS</replaceable></option></term>
311
All Mandos servers are tried repeatedly until a password
312
is received. This value specifies, in seconds, how long
313
between each successive try <emphasis>for the same
314
server</emphasis>. The default is 10 seconds.
320
<term><option>--network-hook-dir=<replaceable
321
>DIR</replaceable></option></term>
324
Network hook directory. The default directory is
325
<quote><filename class="directory"
326
>/lib/mandos/network-hooks.d</filename></quote>.
332
<term><option>--debug</option></term>
335
Enable debug mode. This will enable a lot of output to
336
standard error about what the program is doing. The
337
program will still perform all other functions normally.
340
It will also enable debug mode in the Avahi and GnuTLS
341
libraries, making them print large amounts of debugging
348
<term><option>--help</option></term>
349
<term><option>-?</option></term>
352
Gives a help message about options and their meanings.
358
<term><option>--usage</option></term>
361
Gives a short usage message.
367
<term><option>--version</option></term>
368
<term><option>-V</option></term>
371
Prints the program version.
378
<refsect1 id="overview">
379
<title>OVERVIEW</title>
380
<xi:include href="../overview.xml"/>
382
This program is the client part. It is a plugin started by
383
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
384
<manvolnum>8mandos</manvolnum></citerefentry> which will run in
385
an initial <acronym>RAM</acronym> disk environment.
388
This program could, theoretically, be used as a keyscript in
389
<filename>/etc/crypttab</filename>, but it would then be
390
impossible to enter a password for the encrypted root disk at
391
the console, since this program does not read from the console
392
at all. This is why a separate plugin runner (<citerefentry>
393
<refentrytitle>plugin-runner</refentrytitle>
394
<manvolnum>8mandos</manvolnum></citerefentry>) is used to run
395
both this program and others in in parallel,
396
<emphasis>one</emphasis> of which will prompt for passwords on
401
<refsect1 id="exit_status">
402
<title>EXIT STATUS</title>
404
This program will exit with a successful (zero) exit status if a
405
server could be found and the password received from it could be
406
successfully decrypted and output on standard output. The
407
program will exit with a non-zero exit status only if a critical
408
error occurs. Otherwise, it will forever connect to any
409
discovered <application>Mandos</application> servers, trying to
410
get a decryptable password and print it.
414
<refsect1 id="environment">
415
<title>ENVIRONMENT</title>
417
This program does not use any environment variables, not even
418
the ones provided by <citerefentry><refentrytitle
419
>cryptsetup</refentrytitle><manvolnum>8</manvolnum>
424
<refsect1 id="files">
428
<term><filename>/conf/conf.d/mandos/pubkey.txt</filename
430
<term><filename>/conf/conf.d/mandos/seckey.txt</filename
434
OpenPGP public and private key files, in <quote>ASCII
435
Armor</quote> format. These are the default file names,
436
they can be changed with the <option>--pubkey</option> and
437
<option>--seckey</option> options.
444
<!-- <refsect1 id="bugs"> -->
445
<!-- <title>BUGS</title> -->
450
<refsect1 id="example">
451
<title>EXAMPLE</title>
453
Note that normally, command line options will not be given
454
directly, but via options for the Mandos <citerefentry
455
><refentrytitle>plugin-runner</refentrytitle>
456
<manvolnum>8mandos</manvolnum></citerefentry>.
460
Normal invocation needs no options, if the network interface
461
is <quote>eth0</quote>:
464
<userinput>&COMMANDNAME;</userinput>
469
Search for Mandos servers (and connect to them) using another
473
<!-- do not wrap this line -->
474
<userinput>&COMMANDNAME; --interface eth1</userinput>
479
Run in debug mode, and use a custom key:
483
<!-- do not wrap this line -->
484
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt</userinput>
490
Run in debug mode, with a custom key, and do not use Zeroconf
491
to locate a server; connect directly to the IPv6 link-local
492
address <quote><systemitem class="ipaddress"
493
>fe80::aede:48ff:fe71:f6f2</systemitem></quote>, port 4711,
494
using interface eth2:
498
<!-- do not wrap this line -->
499
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt --connect fe80::aede:48ff:fe71:f6f2:4711 --interface eth2</userinput>
505
<refsect1 id="security">
506
<title>SECURITY</title>
508
This program is set-uid to root, but will switch back to the
509
original (and presumably non-privileged) user and group after
510
bringing up the network interface.
513
To use this program for its intended purpose (see <xref
514
linkend="purpose"/>), the password for the root file system will
515
have to be given out to be stored in a server computer, after
516
having been encrypted using an OpenPGP key. This encrypted data
517
which will be stored in a server can only be decrypted by the
518
OpenPGP key, and the data will only be given out to those
519
clients who can prove they actually have that key. This key,
520
however, is stored unencrypted on the client side in its initial
521
<acronym>RAM</acronym> disk image file system. This is normally
522
readable by all, but this is normally fixed during installation
523
of this program; file permissions are set so that no-one is able
527
The only remaining weak point is that someone with physical
528
access to the client hard drive might turn off the client
529
computer, read the OpenPGP keys directly from the hard drive,
530
and communicate with the server. To safeguard against this, the
531
server is supposed to notice the client disappearing and stop
532
giving out the encrypted data. Therefore, it is important to
533
set the timeout and checker interval values tightly on the
534
server. See <citerefentry><refentrytitle
535
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
538
It will also help if the checker program on the server is
539
configured to request something from the client which can not be
540
spoofed by someone else on the network, unlike unencrypted
541
<acronym>ICMP</acronym> echo (<quote>ping</quote>) replies.
544
<emphasis>Note</emphasis>: This makes it completely insecure to
545
have <application >Mandos</application> clients which dual-boot
546
to another operating system which is <emphasis>not</emphasis>
547
trusted to keep the initial <acronym>RAM</acronym> disk image
552
<refsect1 id="see_also">
553
<title>SEE ALSO</title>
555
<citerefentry><refentrytitle>intro</refentrytitle>
556
<manvolnum>8mandos</manvolnum></citerefentry>,
557
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
558
<manvolnum>8</manvolnum></citerefentry>,
559
<citerefentry><refentrytitle>crypttab</refentrytitle>
560
<manvolnum>5</manvolnum></citerefentry>,
561
<citerefentry><refentrytitle>mandos</refentrytitle>
562
<manvolnum>8</manvolnum></citerefentry>,
563
<citerefentry><refentrytitle>password-prompt</refentrytitle>
564
<manvolnum>8mandos</manvolnum></citerefentry>,
565
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
566
<manvolnum>8mandos</manvolnum></citerefentry>
571
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
575
Zeroconf is the network protocol standard used for finding
576
Mandos servers on the local network.
582
<ulink url="http://www.avahi.org/">Avahi</ulink>
586
Avahi is the library this program calls to find Zeroconf
593
<ulink url="http://www.gnu.org/software/gnutls/"
598
GnuTLS is the library this client uses to implement TLS for
599
communicating securely with the server, and at the same time
600
send the public OpenPGP key to the server.
606
<ulink url="http://www.gnupg.org/related_software/gpgme/"
611
GPGME is the library used to decrypt the OpenPGP data sent
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
This client uses 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 received from the server is binary encrypted
672
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
677
This is implemented by GnuTLS and used by this program so
678
that OpenPGP keys can be used.
686
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687
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688
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