69
48
<refname><command>&COMMANDNAME;</command></refname>
50
Client for <application>Mandos</application>
77
56
<command>&COMMANDNAME;</command>
78
<arg choice='opt'>--connect<arg choice='plain'>IP</arg></arg>
79
<arg choice='opt'>--keydir<arg choice='plain'>KEYDIR</arg></arg>
80
<arg choice='opt'>--interface<arg choice='plain'>INTERFACE</arg></arg>
81
<arg choice='opt'>--pubkey<arg choice='plain'>PUBKEY</arg></arg>
82
<arg choice='opt'>--seckey<arg choice='plain'>SECKEY</arg></arg>
83
<arg choice='opt'>--priority<arg choice='plain'>PRIORITY</arg></arg>
84
<arg choice='opt'>--dh-bits<arg choice='plain'>BITS</arg></arg>
85
<arg choice='opt'>--debug</arg>
88
<command>&COMMANDNAME;</command>
89
<arg choice='plain'>--help</arg>
92
<command>&COMMANDNAME;</command>
93
<arg choice='plain'>--usage</arg>
96
<command>&COMMANDNAME;</command>
97
<arg choice='plain'>--version</arg>
58
<arg choice="plain"><option>--connect
59
<replaceable>ADDRESS</replaceable><literal>:</literal
60
><replaceable>PORT</replaceable></option></arg>
61
<arg choice="plain"><option>-c
62
<replaceable>ADDRESS</replaceable><literal>:</literal
63
><replaceable>PORT</replaceable></option></arg>
67
<arg choice="plain"><option>--interface
68
<replaceable>NAME</replaceable></option></arg>
69
<arg choice="plain"><option>-i
70
<replaceable>NAME</replaceable></option></arg>
74
<arg choice="plain"><option>--pubkey
75
<replaceable>FILE</replaceable></option></arg>
76
<arg choice="plain"><option>-p
77
<replaceable>FILE</replaceable></option></arg>
81
<arg choice="plain"><option>--seckey
82
<replaceable>FILE</replaceable></option></arg>
83
<arg choice="plain"><option>-s
84
<replaceable>FILE</replaceable></option></arg>
88
<option>--priority <replaceable>STRING</replaceable></option>
92
<option>--dh-bits <replaceable>BITS</replaceable></option>
96
<option>--delay <replaceable>SECONDS</replaceable></option>
100
<option>--debug</option>
104
<command>&COMMANDNAME;</command>
106
<arg choice="plain"><option>--help</option></arg>
107
<arg choice="plain"><option>-?</option></arg>
111
<command>&COMMANDNAME;</command>
112
<arg choice="plain"><option>--usage</option></arg>
115
<command>&COMMANDNAME;</command>
117
<arg choice="plain"><option>--version</option></arg>
118
<arg choice="plain"><option>-V</option></arg>
101
123
<refsect1 id="description">
102
124
<title>DESCRIPTION</title>
104
<command>&COMMANDNAME;</command> is a mandos plugin that works
105
like a client program that through avahi detects mandos servers,
106
sets up a gnutls connect and request a encrypted password. Any
107
passwords given is automaticly decrypted and passed to
126
<command>&COMMANDNAME;</command> is a client program that
127
communicates with <citerefentry><refentrytitle
128
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>
129
to get a password. In slightly more detail, this client program
130
brings up a network interface, uses the interface’s IPv6
131
link-local address to get network connectivity, uses Zeroconf to
132
find servers on the local network, and communicates with servers
133
using TLS with an OpenPGP key to ensure authenticity and
134
confidentiality. This client program keeps running, trying all
135
servers on the network, until it receives a satisfactory reply
136
or a TERM signal is received. If no servers are found, or after
137
all servers have been tried, it waits indefinitely for new
141
This program is not meant to be run directly; it is really meant
142
to run as a plugin of the <application>Mandos</application>
143
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
144
<manvolnum>8mandos</manvolnum></citerefentry>, which runs in the
145
initial <acronym>RAM</acronym> disk environment because it is
146
specified as a <quote>keyscript</quote> in the <citerefentry>
147
<refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
148
</citerefentry> file.
152
<refsect1 id="purpose">
153
<title>PURPOSE</title>
155
The purpose of this is to enable <emphasis>remote and unattended
156
rebooting</emphasis> of client host computer with an
157
<emphasis>encrypted root file system</emphasis>. See <xref
158
linkend="overview"/> for details.
112
162
<refsect1 id="options">
113
163
<title>OPTIONS</title>
115
Commonly not invoked as command lines but from configuration
116
file of plugin runner.
165
This program is commonly not invoked from the command line; it
166
is normally started by the <application>Mandos</application>
167
plugin runner, see <citerefentry><refentrytitle
168
>plugin-runner</refentrytitle><manvolnum>8mandos</manvolnum>
169
</citerefentry>. Any command line options this program accepts
170
are therefore normally provided by the plugin runner, and not
121
<term><literal>-c</literal>, <literal>--connect=<replaceable>
122
IP</replaceable></literal></term>
125
Connect directly to a specified mandos server
131
<term><literal>-d</literal>, <literal>--keydir=<replaceable>
132
KEYDIR</replaceable></literal></term>
135
Directory where the openpgp keyring is
141
<term><literal>-i</literal>, <literal>--interface=
142
<replaceable>INTERFACE</replaceable></literal></term>
145
Interface that Avahi will conntect through
151
<term><literal>-p</literal>, <literal>--pubkey=<replaceable>
152
PUBKEY</replaceable></literal></term>
155
Public openpgp key for gnutls authentication
161
<term><literal>-s</literal>, <literal>--seckey=<replaceable>
162
SECKEY</replaceable></literal></term>
165
Secret openpgp key for gnutls authentication
171
<term><literal>--priority=<replaceable>PRIORITY</replaceable>
181
<term><literal>--dh-bits=<replaceable>BITS</replaceable>
185
dh-bits to use in gnutls communication
191
<term><literal>--debug</literal></term>
200
<term><literal>-?</literal>, <literal>--help</literal></term>
209
<term><literal>--usage</literal></term>
212
Gives a short usage message
218
<term><literal>-V</literal>, <literal>--version</literal></term>
221
Prints the program version
176
<term><option>--connect=<replaceable
177
>ADDRESS</replaceable><literal>:</literal><replaceable
178
>PORT</replaceable></option></term>
180
<replaceable>ADDRESS</replaceable><literal>:</literal
181
><replaceable>PORT</replaceable></option></term>
184
Do not use Zeroconf to locate servers. Connect directly
185
to only one specified <application>Mandos</application>
186
server. Note that an IPv6 address has colon characters in
187
it, so the <emphasis>last</emphasis> colon character is
188
assumed to separate the address from the port number.
191
This option is normally only useful for testing and
198
<term><option>--interface=<replaceable
199
>NAME</replaceable></option></term>
201
<replaceable>NAME</replaceable></option></term>
204
Network interface that will be brought up and scanned for
205
Mandos servers to connect to. The default is the empty
206
string, which will automatically choose an appropriate
210
If the <option>--connect</option> option is used, this
211
specifies the interface to use to connect to the address
215
Note that since this program will normally run in the
216
initial RAM disk environment, the interface must be an
217
interface which exists at that stage. Thus, the interface
218
can not be a pseudo-interface such as <quote>br0</quote>
219
or <quote>tun0</quote>; such interfaces will not exist
220
until much later in the boot process, and can not be used
224
<replaceable>NAME</replaceable> can be the string
225
<quote><literal>none</literal></quote>; this will not use
226
any specific interface, and will not bring up an interface
227
on startup. This is not recommended, and only meant for
234
<term><option>--pubkey=<replaceable
235
>FILE</replaceable></option></term>
237
<replaceable>FILE</replaceable></option></term>
240
OpenPGP public key file name. The default name is
241
<quote><filename>/conf/conf.d/mandos/pubkey.txt</filename
248
<term><option>--seckey=<replaceable
249
>FILE</replaceable></option></term>
251
<replaceable>FILE</replaceable></option></term>
254
OpenPGP secret key file name. The default name is
255
<quote><filename>/conf/conf.d/mandos/seckey.txt</filename
262
<term><option>--priority=<replaceable
263
>STRING</replaceable></option></term>
265
<xi:include href="../mandos-options.xml"
266
xpointer="priority"/>
271
<term><option>--dh-bits=<replaceable
272
>BITS</replaceable></option></term>
275
Sets the number of bits to use for the prime number in the
276
TLS Diffie-Hellman key exchange. Default is 1024.
282
<term><option>--delay=<replaceable
283
>SECONDS</replaceable></option></term>
286
After bringing the network interface up, the program waits
287
for the interface to arrive in a <quote>running</quote>
288
state before proceeding. During this time, the kernel log
289
level will be lowered to reduce clutter on the system
290
console, alleviating any other plugins which might be
291
using the system console. This option sets the upper
292
limit of seconds to wait. The default is 2.5 seconds.
298
<term><option>--debug</option></term>
301
Enable debug mode. This will enable a lot of output to
302
standard error about what the program is doing. The
303
program will still perform all other functions normally.
306
It will also enable debug mode in the Avahi and GnuTLS
307
libraries, making them print large amounts of debugging
314
<term><option>--help</option></term>
315
<term><option>-?</option></term>
318
Gives a help message about options and their meanings.
324
<term><option>--usage</option></term>
327
Gives a short usage message.
333
<term><option>--version</option></term>
334
<term><option>-V</option></term>
337
Prints the program version.
344
<refsect1 id="overview">
345
<title>OVERVIEW</title>
346
<xi:include href="../overview.xml"/>
348
This program is the client part. It is a plugin started by
349
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
350
<manvolnum>8mandos</manvolnum></citerefentry> which will run in
351
an initial <acronym>RAM</acronym> disk environment.
354
This program could, theoretically, be used as a keyscript in
355
<filename>/etc/crypttab</filename>, but it would then be
356
impossible to enter a password for the encrypted root disk at
357
the console, since this program does not read from the console
358
at all. This is why a separate plugin runner (<citerefentry>
359
<refentrytitle>plugin-runner</refentrytitle>
360
<manvolnum>8mandos</manvolnum></citerefentry>) is used to run
361
both this program and others in in parallel,
362
<emphasis>one</emphasis> of which will prompt for passwords on
228
367
<refsect1 id="exit_status">
229
368
<title>EXIT STATUS</title>
370
This program will exit with a successful (zero) exit status if a
371
server could be found and the password received from it could be
372
successfully decrypted and output on standard output. The
373
program will exit with a non-zero exit status only if a critical
374
error occurs. Otherwise, it will forever connect to new
375
<application>Mandos</application> servers as they appear, trying
376
to get a decryptable password and print it.
234
380
<refsect1 id="environment">
235
381
<title>ENVIRONMENT</title>
383
This program does not use any environment variables, not even
384
the ones provided by <citerefentry><refentrytitle
385
>cryptsetup</refentrytitle><manvolnum>8</manvolnum>
390
<refsect1 id="files">
241
391
<title>FILES</title>
394
<term><filename>/conf/conf.d/mandos/pubkey.txt</filename
396
<term><filename>/conf/conf.d/mandos/seckey.txt</filename
400
OpenPGP public and private key files, in <quote>ASCII
401
Armor</quote> format. These are the default file names,
402
they can be changed with the <option>--pubkey</option> and
403
<option>--seckey</option> options.
410
<!-- <refsect1 id="bugs"> -->
411
<!-- <title>BUGS</title> -->
252
416
<refsect1 id="example">
253
417
<title>EXAMPLE</title>
419
Note that normally, command line options will not be given
420
directly, but via options for the Mandos <citerefentry
421
><refentrytitle>plugin-runner</refentrytitle>
422
<manvolnum>8mandos</manvolnum></citerefentry>.
426
Normal invocation needs no options, if the network interface
427
is <quote>eth0</quote>:
430
<userinput>&COMMANDNAME;</userinput>
435
Search for Mandos servers (and connect to them) using another
439
<!-- do not wrap this line -->
440
<userinput>&COMMANDNAME; --interface eth1</userinput>
445
Run in debug mode, and use a custom key:
449
<!-- do not wrap this line -->
450
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt</userinput>
456
Run in debug mode, with a custom key, and do not use Zeroconf
457
to locate a server; connect directly to the IPv6 link-local
458
address <quote><systemitem class="ipaddress"
459
>fe80::aede:48ff:fe71:f6f2</systemitem></quote>, port 4711,
460
using interface eth2:
464
<!-- do not wrap this line -->
465
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt --connect fe80::aede:48ff:fe71:f6f2:4711 --interface eth2</userinput>
258
471
<refsect1 id="security">
259
472
<title>SECURITY</title>
474
This program is set-uid to root, but will switch back to the
475
original (and presumably non-privileged) user and group after
476
bringing up the network interface.
479
To use this program for its intended purpose (see <xref
480
linkend="purpose"/>), the password for the root file system will
481
have to be given out to be stored in a server computer, after
482
having been encrypted using an OpenPGP key. This encrypted data
483
which will be stored in a server can only be decrypted by the
484
OpenPGP key, and the data will only be given out to those
485
clients who can prove they actually have that key. This key,
486
however, is stored unencrypted on the client side in its initial
487
<acronym>RAM</acronym> disk image file system. This is normally
488
readable by all, but this is normally fixed during installation
489
of this program; file permissions are set so that no-one is able
493
The only remaining weak point is that someone with physical
494
access to the client hard drive might turn off the client
495
computer, read the OpenPGP keys directly from the hard drive,
496
and communicate with the server. To safeguard against this, the
497
server is supposed to notice the client disappearing and stop
498
giving out the encrypted data. Therefore, it is important to
499
set the timeout and checker interval values tightly on the
500
server. See <citerefentry><refentrytitle
501
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
504
It will also help if the checker program on the server is
505
configured to request something from the client which can not be
506
spoofed by someone else on the network, unlike unencrypted
507
<acronym>ICMP</acronym> echo (<quote>ping</quote>) replies.
510
<emphasis>Note</emphasis>: This makes it completely insecure to
511
have <application >Mandos</application> clients which dual-boot
512
to another operating system which is <emphasis>not</emphasis>
513
trusted to keep the initial <acronym>RAM</acronym> disk image
264
518
<refsect1 id="see_also">
265
519
<title>SEE ALSO</title>
268
<citerefentry><refentrytitle>mandos</refentrytitle>
269
<manvolnum>8</manvolnum></citerefentry>
273
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
274
<manvolnum>8mandos</manvolnum></citerefentry>
278
<citerefentry><refentrytitle>password-prompt</refentrytitle>
279
<manvolnum>8mandos</manvolnum></citerefentry>
283
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
287
<ulink url="http://www.avahi.org/">Avahi</ulink>
292
url="http://www.gnu.org/software/gnutls/">GnuTLS</ulink>
297
url="http://www.gnupg.org/related_software/gpgme/">
302
<citation>RFC 4880: <citetitle>OpenPGP Message
303
Format</citetitle></citation>
307
<citation>RFC 5081: <citetitle>Using OpenPGP Keys for
308
Transport Layer Security</citetitle></citation>
312
<citation>RFC 4291: <citetitle>IP Version 6 Addressing
313
Architecture</citetitle>, section 2.5.6, Link-Local IPv6
314
Unicast Addresses</citation>
521
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
522
<manvolnum>8</manvolnum></citerefentry>,
523
<citerefentry><refentrytitle>crypttab</refentrytitle>
524
<manvolnum>5</manvolnum></citerefentry>,
525
<citerefentry><refentrytitle>mandos</refentrytitle>
526
<manvolnum>8</manvolnum></citerefentry>,
527
<citerefentry><refentrytitle>password-prompt</refentrytitle>
528
<manvolnum>8mandos</manvolnum></citerefentry>,
529
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
530
<manvolnum>8mandos</manvolnum></citerefentry>
535
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
539
Zeroconf is the network protocol standard used for finding
540
Mandos servers on the local network.
546
<ulink url="http://www.avahi.org/">Avahi</ulink>
550
Avahi is the library this program calls to find Zeroconf
557
<ulink url="http://www.gnu.org/software/gnutls/"
562
GnuTLS is the library this client uses to implement TLS for
563
communicating securely with the server, and at the same time
564
send the public OpenPGP key to the server.
570
<ulink url="http://www.gnupg.org/related_software/gpgme/"
575
GPGME is the library used to decrypt the OpenPGP data sent
582
RFC 4291: <citetitle>IP Version 6 Addressing
583
Architecture</citetitle>
588
<term>Section 2.2: <citetitle>Text Representation of
589
Addresses</citetitle></term>
590
<listitem><para/></listitem>
593
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
594
Address</citetitle></term>
595
<listitem><para/></listitem>
598
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
599
Addresses</citetitle></term>
602
This client uses IPv6 link-local addresses, which are
603
immediately usable since a link-local addresses is
604
automatically assigned to a network interfaces when it
614
RFC 4346: <citetitle>The Transport Layer Security (TLS)
615
Protocol Version 1.1</citetitle>
619
TLS 1.1 is the protocol implemented by GnuTLS.
625
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
629
The data received from the server is binary encrypted
636
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
641
This is implemented by GnuTLS and used by this program so
642
that OpenPGP keys can be used.
320
650
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321
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322
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