67
49
<refname><command>&COMMANDNAME;</command></refname>
51
Client for <application>Mandos</application>
75
57
<command>&COMMANDNAME;</command>
76
<arg choice='opt'>--connect<arg choice='plain'>IP</arg></arg>
77
<arg choice='opt'>--keydir<arg choice='plain'>KEYDIR</arg></arg>
78
<arg choice='opt'>--interface<arg choice='plain'>INTERFACE</arg></arg>
79
<arg choice='opt'>--pubkey<arg choice='plain'>PUBKEY</arg></arg>
80
<arg choice='opt'>--seckey<arg choice='plain'>SECKEY</arg></arg>
81
<arg choice='opt'>--priority<arg choice='plain'>PRIORITY</arg></arg>
82
<arg choice='opt'>--dh-bits<arg choice='plain'>BITS</arg></arg>
83
<arg choice='opt'>--debug</arg>
86
<command>&COMMANDNAME;</command>
87
<arg choice='plain'>--help</arg>
90
<command>&COMMANDNAME;</command>
91
<arg choice='plain'>--usage</arg>
94
<command>&COMMANDNAME;</command>
95
<arg choice='plain'>--version</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
106
<replaceable>DIR</replaceable></option>
110
<option>--debug</option>
114
<command>&COMMANDNAME;</command>
116
<arg choice="plain"><option>--help</option></arg>
117
<arg choice="plain"><option>-?</option></arg>
121
<command>&COMMANDNAME;</command>
122
<arg choice="plain"><option>--usage</option></arg>
125
<command>&COMMANDNAME;</command>
127
<arg choice="plain"><option>--version</option></arg>
128
<arg choice="plain"><option>-V</option></arg>
99
133
<refsect1 id="description">
100
134
<title>DESCRIPTION</title>
102
<command>&COMMANDNAME;</command> is a mandos plugin that works
103
like a client program that through avahi detects mandos servers,
104
sets up a gnutls connect and request a encrypted password. Any
105
passwords given is automaticly decrypted and passed to
136
<command>&COMMANDNAME;</command> is a client program that
137
communicates with <citerefentry><refentrytitle
138
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>
139
to get a password. In slightly more detail, this client program
140
brings up a network interface, uses the interface’s IPv6
141
link-local address to get network connectivity, uses Zeroconf to
142
find servers on the local network, and communicates with servers
143
using TLS with an OpenPGP key to ensure authenticity and
144
confidentiality. This client program keeps running, trying all
145
servers on the network, until it receives a satisfactory reply
146
or a TERM signal. After all servers have been tried, all
147
servers are periodically retried. If no servers are found it
148
will wait indefinitely for new servers to appear.
151
The network interface is selected like this: If an interface is
152
specified using the <option>--interface</option> option, that
153
interface is used. Otherwise, <command>&COMMANDNAME;</command>
154
will choose any interface that is up and running and is not a
155
loopback interface, is not a point-to-point interface, is
156
capable of broadcasting and does not have the NOARP flag (see
157
<citerefentry><refentrytitle>netdevice</refentrytitle>
158
<manvolnum>7</manvolnum></citerefentry>). (If the
159
<option>--connect</option> option is used, point-to-point
160
interfaces and non-broadcast interfaces are accepted.) If no
161
acceptable interfaces are found, re-run the check but without
162
the <quote>up and running</quote> requirement, and manually take
163
the selected interface up (and later take it down on program
167
Before a network interface is selected, all <quote>network
168
hooks</quote> are run; see <xref linkend="network-hooks"/>.
171
This program is not meant to be run directly; it is really meant
172
to run as a plugin of the <application>Mandos</application>
173
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
174
<manvolnum>8mandos</manvolnum></citerefentry>, which runs in the
175
initial <acronym>RAM</acronym> disk environment because it is
176
specified as a <quote>keyscript</quote> in the <citerefentry>
177
<refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
178
</citerefentry> file.
182
<refsect1 id="purpose">
183
<title>PURPOSE</title>
185
The purpose of this is to enable <emphasis>remote and unattended
186
rebooting</emphasis> of client host computer with an
187
<emphasis>encrypted root file system</emphasis>. See <xref
188
linkend="overview"/> for details.
110
192
<refsect1 id="options">
111
193
<title>OPTIONS</title>
113
Commonly not invoked as command lines but from configuration
114
file of plugin runner.
195
This program is commonly not invoked from the command line; it
196
is normally started by the <application>Mandos</application>
197
plugin runner, see <citerefentry><refentrytitle
198
>plugin-runner</refentrytitle><manvolnum>8mandos</manvolnum>
199
</citerefentry>. Any command line options this program accepts
200
are therefore normally provided by the plugin runner, and not
119
<term><literal>-c</literal>, <literal>--connect=<replaceable>
120
IP</replaceable></literal></term>
123
Connect directly to a sepcified mandos server
129
<term><literal>-d</literal>, <literal>--keydir=<replaceable>
130
KEYDIR</replaceable></literal></term>
133
Directory where the openpgp keyring is
139
<term><literal>-i</literal>, <literal>--interface=
140
<replaceable>INTERFACE</replaceable></literal></term>
143
Interface that Avahi will conntect through
149
<term><literal>-p</literal>, <literal>--pubkey=<replaceable>
150
PUBKEY</replaceable></literal></term>
153
Public openpgp key for gnutls authentication
159
<term><literal>-s</literal>, <literal>--seckey=<replaceable>
160
SECKEY</replaceable></literal></term>
163
Secret openpgp key for gnutls authentication
169
<term><literal>--priority=<replaceable>PRIORITY</replaceable>
179
<term><literal>--dh-bits=<replaceable>BITS</replaceable>
183
dh-bits to use in gnutls communication
189
<term><literal>--debug</literal></term>
198
<term><literal>-?</literal>, <literal>--help</literal></term>
207
<term><literal>--usage</literal></term>
210
Gives a short usage message
216
<term><literal>-V</literal>, <literal>--version</literal></term>
219
Prints the program version
206
<term><option>--connect=<replaceable
207
>ADDRESS</replaceable><literal>:</literal><replaceable
208
>PORT</replaceable></option></term>
210
<replaceable>ADDRESS</replaceable><literal>:</literal
211
><replaceable>PORT</replaceable></option></term>
214
Do not use Zeroconf to locate servers. Connect directly
215
to only one specified <application>Mandos</application>
216
server. Note that an IPv6 address has colon characters in
217
it, so the <emphasis>last</emphasis> colon character is
218
assumed to separate the address from the port number.
221
This option is normally only useful for testing and
228
<term><option>--interface=<replaceable
229
>NAME</replaceable></option></term>
231
<replaceable>NAME</replaceable></option></term>
234
Network interface that will be brought up and scanned for
235
Mandos servers to connect to. The default is the empty
236
string, which will automatically choose an appropriate
240
If the <option>--connect</option> option is used, this
241
specifies the interface to use to connect to the address
245
Note that since this program will normally run in the
246
initial RAM disk environment, the interface must be an
247
interface which exists at that stage. Thus, the interface
248
can not be a pseudo-interface such as <quote>br0</quote>
249
or <quote>tun0</quote>; such interfaces will not exist
250
until much later in the boot process, and can not be used
251
by this program, unless created by a <quote>network
252
hook</quote> — see <xref linkend="network-hooks"/>.
255
<replaceable>NAME</replaceable> can be the string
256
<quote><literal>none</literal></quote>; this will not use
257
any specific interface, and will not bring up an interface
258
on startup. This is not recommended, and only meant for
265
<term><option>--pubkey=<replaceable
266
>FILE</replaceable></option></term>
268
<replaceable>FILE</replaceable></option></term>
271
OpenPGP public key file name. The default name is
272
<quote><filename>/conf/conf.d/mandos/pubkey.txt</filename
279
<term><option>--seckey=<replaceable
280
>FILE</replaceable></option></term>
282
<replaceable>FILE</replaceable></option></term>
285
OpenPGP secret key file name. The default name is
286
<quote><filename>/conf/conf.d/mandos/seckey.txt</filename
293
<term><option>--priority=<replaceable
294
>STRING</replaceable></option></term>
296
<xi:include href="../mandos-options.xml"
297
xpointer="priority"/>
302
<term><option>--dh-bits=<replaceable
303
>BITS</replaceable></option></term>
306
Sets the number of bits to use for the prime number in the
307
TLS Diffie-Hellman key exchange. Default is 1024.
313
<term><option>--delay=<replaceable
314
>SECONDS</replaceable></option></term>
317
After bringing the network interface up, the program waits
318
for the interface to arrive in a <quote>running</quote>
319
state before proceeding. During this time, the kernel log
320
level will be lowered to reduce clutter on the system
321
console, alleviating any other plugins which might be
322
using the system console. This option sets the upper
323
limit of seconds to wait. The default is 2.5 seconds.
329
<term><option>--retry=<replaceable
330
>SECONDS</replaceable></option></term>
333
All Mandos servers are tried repeatedly until a password
334
is received. This value specifies, in seconds, how long
335
between each successive try <emphasis>for the same
336
server</emphasis>. The default is 10 seconds.
342
<term><option>--network-hook-dir=<replaceable
343
>DIR</replaceable></option></term>
346
Network hook directory. The default directory is
347
<quote><filename class="directory"
348
>/lib/mandos/network-hooks.d</filename></quote>.
354
<term><option>--debug</option></term>
357
Enable debug mode. This will enable a lot of output to
358
standard error about what the program is doing. The
359
program will still perform all other functions normally.
362
It will also enable debug mode in the Avahi and GnuTLS
363
libraries, making them print large amounts of debugging
370
<term><option>--help</option></term>
371
<term><option>-?</option></term>
374
Gives a help message about options and their meanings.
380
<term><option>--usage</option></term>
383
Gives a short usage message.
389
<term><option>--version</option></term>
390
<term><option>-V</option></term>
393
Prints the program version.
400
<refsect1 id="overview">
401
<title>OVERVIEW</title>
402
<xi:include href="../overview.xml"/>
404
This program is the client part. It is a plugin started by
405
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
406
<manvolnum>8mandos</manvolnum></citerefentry> which will run in
407
an initial <acronym>RAM</acronym> disk environment.
410
This program could, theoretically, be used as a keyscript in
411
<filename>/etc/crypttab</filename>, but it would then be
412
impossible to enter a password for the encrypted root disk at
413
the console, since this program does not read from the console
414
at all. This is why a separate plugin runner (<citerefentry>
415
<refentrytitle>plugin-runner</refentrytitle>
416
<manvolnum>8mandos</manvolnum></citerefentry>) is used to run
417
both this program and others in in parallel,
418
<emphasis>one</emphasis> of which (<citerefentry>
419
<refentrytitle>password-prompt</refentrytitle>
420
<manvolnum>8mandos</manvolnum></citerefentry>) will prompt for
421
passwords on the system console.
226
425
<refsect1 id="exit_status">
227
426
<title>EXIT STATUS</title>
428
This program will exit with a successful (zero) exit status if a
429
server could be found and the password received from it could be
430
successfully decrypted and output on standard output. The
431
program will exit with a non-zero exit status only if a critical
432
error occurs. Otherwise, it will forever connect to any
433
discovered <application>Mandos</application> servers, trying to
434
get a decryptable password and print it.
438
<refsect1 id="environment">
439
<title>ENVIRONMENT</title>
441
This program does not use any environment variables, not even
442
the ones provided by <citerefentry><refentrytitle
443
>cryptsetup</refentrytitle><manvolnum>8</manvolnum>
448
<refsect1 id="network-hooks">
449
<title>NETWORK HOOKS</title>
451
If a network interface like a bridge or tunnel is required to
452
find a Mandos server, this requires the interface to be up and
453
running before <command>&COMMANDNAME;</command> starts looking
454
for Mandos servers. This can be accomplished by creating a
455
<quote>network hook</quote> program, and placing it in a special
459
Before the network is used (and again before program exit), any
460
runnable programs found in the network hook directory are run
461
with the argument <quote><literal>start</literal></quote> or
462
<quote><literal>stop</literal></quote>. This should bring up or
463
down, respectively, any network interface which
464
<command>&COMMANDNAME;</command> should use.
466
<refsect2 id="hook-requirements">
467
<title>REQUIREMENTS</title>
469
A network hook must be an executable file, and its name must
470
consist entirely of upper and lower case letters, digits,
471
underscores, periods, and hyphens.
474
A network hook will receive one argument, which can be one of
479
<term><literal>start</literal></term>
482
This should make the network hook create (if necessary)
483
and bring up a network interface.
488
<term><literal>stop</literal></term>
491
This should make the network hook take down a network
492
interface, and delete it if it did not exist previously.
497
<term><literal>files</literal></term>
500
This should make the network hook print, <emphasis>one
501
file per line</emphasis>, all the files needed for it to
502
run. (These files will be copied into the initial RAM
503
filesystem.) Typical use is for a network hook which is
504
a shell script to print its needed binaries.
507
It is not necessary to print any non-executable files
508
already in the network hook directory, these will be
509
copied implicitly if they otherwise satisfy the name
515
<term><literal>modules</literal></term>
518
This should make the network hook print, <emphasis>on
519
separate lines</emphasis>, all the kernel modules needed
520
for it to run. (These modules will be copied into the
521
initial RAM filesystem.) For instance, a tunnel
523
<quote><literal>tun</literal></quote> module.
529
The network hook will be provided with a number of environment
534
<term><envar>MANDOSNETHOOKDIR</envar></term>
537
The network hook directory, specified to
538
<command>&COMMANDNAME;</command> by the
539
<option>--network-hook-dir</option> option. Note: this
540
should <emphasis>always</emphasis> be used by the
541
network hook to refer to itself or any files in the hook
542
directory it may require.
547
<term><envar>DEVICE</envar></term>
550
The network interface, as specified to
551
<command>&COMMANDNAME;</command> by the
552
<option>--interface</option> option. If this is not the
553
interface a hook will bring up, there is no reason for a
559
<term><envar>MODE</envar></term>
562
This will be the same as the first argument;
563
i.e. <quote><literal>start</literal></quote>,
564
<quote><literal>stop</literal></quote>,
565
<quote><literal>files</literal></quote>, or
566
<quote><literal>modules</literal></quote>.
571
<term><envar>VERBOSITY</envar></term>
574
This will be the <quote><literal>1</literal></quote> if
575
the <option>--debug</option> option is passed to
576
<command>&COMMANDNAME;</command>, otherwise
577
<quote><literal>0</literal></quote>.
582
<term><envar>DELAY</envar></term>
585
This will be the same as the <option>--delay</option>
586
option passed to <command>&COMMANDNAME;</command>. Is
587
only set if <envar>MODE</envar> is
588
<quote><literal>start</literal></quote> or
589
<quote><literal>stop</literal></quote>.
594
<term><envar>CONNECT</envar></term>
597
This will be the same as the <option>--connect</option>
598
option passed to <command>&COMMANDNAME;</command>. Is
599
only set if <option>--connect</option> is passed and
600
<envar>MODE</envar> is
601
<quote><literal>start</literal></quote> or
602
<quote><literal>stop</literal></quote>.
608
A hook may not read from standard input, and should be
609
restrictive in printing to standard output or standard error
610
unless <varname>VERBOSITY</varname> is
611
<quote><literal>1</literal></quote>.
616
<refsect1 id="files">
233
617
<title>FILES</title>
238
<refsect1 id="notes">
250
<refsect1 id="examples">
251
<title>EXAMPLES</title>
620
<term><filename>/conf/conf.d/mandos/pubkey.txt</filename
622
<term><filename>/conf/conf.d/mandos/seckey.txt</filename
626
OpenPGP public and private key files, in <quote>ASCII
627
Armor</quote> format. These are the default file names,
628
they can be changed with the <option>--pubkey</option> and
629
<option>--seckey</option> options.
635
class="directory">/lib/mandos/network-hooks.d</filename></term>
638
Directory where network hooks are located. Change this
639
with the <option>--network-hook-dir</option> option. See
640
<xref linkend="network-hooks"/>.
647
<!-- <refsect1 id="bugs"> -->
648
<!-- <title>BUGS</title> -->
653
<refsect1 id="example">
654
<title>EXAMPLE</title>
656
Note that normally, command line options will not be given
657
directly, but via options for the Mandos <citerefentry
658
><refentrytitle>plugin-runner</refentrytitle>
659
<manvolnum>8mandos</manvolnum></citerefentry>.
663
Normal invocation needs no options, if the network interface
664
is <quote>eth0</quote>:
667
<userinput>&COMMANDNAME;</userinput>
672
Search for Mandos servers (and connect to them) using another
676
<!-- do not wrap this line -->
677
<userinput>&COMMANDNAME; --interface eth1</userinput>
682
Run in debug mode, and use a custom key:
686
<!-- do not wrap this line -->
687
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt</userinput>
693
Run in debug mode, with a custom key, and do not use Zeroconf
694
to locate a server; connect directly to the IPv6 link-local
695
address <quote><systemitem class="ipaddress"
696
>fe80::aede:48ff:fe71:f6f2</systemitem></quote>, port 4711,
697
using interface eth2:
701
<!-- do not wrap this line -->
702
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt --connect fe80::aede:48ff:fe71:f6f2:4711 --interface eth2</userinput>
256
708
<refsect1 id="security">
257
709
<title>SECURITY</title>
711
This program is set-uid to root, but will switch back to the
712
original (and presumably non-privileged) user and group after
713
bringing up the network interface.
716
To use this program for its intended purpose (see <xref
717
linkend="purpose"/>), the password for the root file system will
718
have to be given out to be stored in a server computer, after
719
having been encrypted using an OpenPGP key. This encrypted data
720
which will be stored in a server can only be decrypted by the
721
OpenPGP key, and the data will only be given out to those
722
clients who can prove they actually have that key. This key,
723
however, is stored unencrypted on the client side in its initial
724
<acronym>RAM</acronym> disk image file system. This is normally
725
readable by all, but this is normally fixed during installation
726
of this program; file permissions are set so that no-one is able
730
The only remaining weak point is that someone with physical
731
access to the client hard drive might turn off the client
732
computer, read the OpenPGP keys directly from the hard drive,
733
and communicate with the server. To safeguard against this, the
734
server is supposed to notice the client disappearing and stop
735
giving out the encrypted data. Therefore, it is important to
736
set the timeout and checker interval values tightly on the
737
server. See <citerefentry><refentrytitle
738
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
741
It will also help if the checker program on the server is
742
configured to request something from the client which can not be
743
spoofed by someone else on the network, unlike unencrypted
744
<acronym>ICMP</acronym> echo (<quote>ping</quote>) replies.
747
<emphasis>Note</emphasis>: This makes it completely insecure to
748
have <application >Mandos</application> clients which dual-boot
749
to another operating system which is <emphasis>not</emphasis>
750
trusted to keep the initial <acronym>RAM</acronym> disk image
262
755
<refsect1 id="see_also">
263
756
<title>SEE ALSO</title>
758
<citerefentry><refentrytitle>intro</refentrytitle>
759
<manvolnum>8mandos</manvolnum></citerefentry>,
760
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
761
<manvolnum>8</manvolnum></citerefentry>,
762
<citerefentry><refentrytitle>crypttab</refentrytitle>
763
<manvolnum>5</manvolnum></citerefentry>,
265
764
<citerefentry><refentrytitle>mandos</refentrytitle>
266
<manvolnum>8</manvolnum></citerefentry>, <citerefentry>
267
<refentrytitle>plugin-runner</refentrytitle>
268
<manvolnum>8mandos</manvolnum></citerefentry> and <citerefentry>
269
<refentrytitle>password-prompt</refentrytitle>
765
<manvolnum>8</manvolnum></citerefentry>,
766
<citerefentry><refentrytitle>password-prompt</refentrytitle>
767
<manvolnum>8mandos</manvolnum></citerefentry>,
768
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
270
769
<manvolnum>8mandos</manvolnum></citerefentry>
774
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
778
Zeroconf is the network protocol standard used for finding
779
Mandos servers on the local network.
785
<ulink url="http://www.avahi.org/">Avahi</ulink>
789
Avahi is the library this program calls to find Zeroconf
796
<ulink url="http://www.gnu.org/software/gnutls/"
801
GnuTLS is the library this client uses to implement TLS for
802
communicating securely with the server, and at the same time
803
send the public OpenPGP key to the server.
809
<ulink url="http://www.gnupg.org/related_software/gpgme/"
814
GPGME is the library used to decrypt the OpenPGP data sent
821
RFC 4291: <citetitle>IP Version 6 Addressing
822
Architecture</citetitle>
827
<term>Section 2.2: <citetitle>Text Representation of
828
Addresses</citetitle></term>
829
<listitem><para/></listitem>
832
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
833
Address</citetitle></term>
834
<listitem><para/></listitem>
837
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
838
Addresses</citetitle></term>
841
This client uses IPv6 link-local addresses, which are
842
immediately usable since a link-local addresses is
843
automatically assigned to a network interfaces when it
853
RFC 4346: <citetitle>The Transport Layer Security (TLS)
854
Protocol Version 1.1</citetitle>
858
TLS 1.1 is the protocol implemented by GnuTLS.
864
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
868
The data received from the server is binary encrypted
875
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
880
This is implemented by GnuTLS and used by this program so
881
that OpenPGP keys can be used.
889
<!-- Local Variables: -->
890
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891
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892
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