67
50
<refname><command>&COMMANDNAME;</command></refname>
52
Client for <application>Mandos</application>
75
58
<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>
60
<arg choice="plain"><option>--connect
61
<replaceable>ADDRESS</replaceable><literal>:</literal
62
><replaceable>PORT</replaceable></option></arg>
63
<arg choice="plain"><option>-c
64
<replaceable>ADDRESS</replaceable><literal>:</literal
65
><replaceable>PORT</replaceable></option></arg>
69
<arg choice="plain"><option>--interface
70
<replaceable>NAME</replaceable><arg rep='repeat'
71
>,<replaceable>NAME</replaceable></arg></option></arg>
72
<arg choice="plain"><option>-i <replaceable>NAME</replaceable
73
><arg rep='repeat'>,<replaceable>NAME</replaceable></arg
78
<arg choice="plain"><option>--pubkey
79
<replaceable>FILE</replaceable></option></arg>
80
<arg choice="plain"><option>-p
81
<replaceable>FILE</replaceable></option></arg>
85
<arg choice="plain"><option>--seckey
86
<replaceable>FILE</replaceable></option></arg>
87
<arg choice="plain"><option>-s
88
<replaceable>FILE</replaceable></option></arg>
92
<option>--priority <replaceable>STRING</replaceable></option>
96
<option>--dh-bits <replaceable>BITS</replaceable></option>
100
<option>--delay <replaceable>SECONDS</replaceable></option>
104
<option>--retry <replaceable>SECONDS</replaceable></option>
108
<option>--network-hook-dir
109
<replaceable>DIR</replaceable></option>
113
<option>--debug</option>
117
<command>&COMMANDNAME;</command>
119
<arg choice="plain"><option>--help</option></arg>
120
<arg choice="plain"><option>-?</option></arg>
124
<command>&COMMANDNAME;</command>
125
<arg choice="plain"><option>--usage</option></arg>
128
<command>&COMMANDNAME;</command>
130
<arg choice="plain"><option>--version</option></arg>
131
<arg choice="plain"><option>-V</option></arg>
99
136
<refsect1 id="description">
100
137
<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
111
<term><literal>-c</literal>, <literal>--connect=<replaceable>
112
IP</replaceable></literal></term>
115
Connect directly to a sepcified mandos server
121
<term><literal>-d</literal>, <literal>--keydir=<replaceable>
122
KEYDIR</replaceable></literal></term>
125
Directory where the openpgp keyring is
131
<term><literal>-i</literal>, <literal>--interface=
132
<replaceable>INTERFACE</replaceable></literal></term>
135
Interface that Avahi will conntect through
141
<term><literal>-p</literal>, <literal>--pubkey=<replaceable>
142
PUBKEY</replaceable></literal></term>
145
Public openpgp key for gnutls authentication
151
<term><literal>-s</literal>, <literal>--seckey=<replaceable>
152
SECKEY</replaceable></literal></term>
155
Secret openpgp key for gnutls authentication
161
<term><literal>--priority=<replaceable>PRIORITY</replaceable>
171
<term><literal>--dh-bits=<replaceable>BITS</replaceable>
175
dh-bits to use in gnutls communication
181
<term><literal>--debug</literal></term>
190
<term><literal>-?</literal>, <literal>--help</literal></term>
199
<term><literal>--usage</literal></term>
202
Gives a short usage message
208
<term><literal>-V</literal>, <literal>--version</literal></term>
211
Prints the program version
139
<command>&COMMANDNAME;</command> is a client program that
140
communicates with <citerefentry><refentrytitle
141
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>
142
to get a password. In slightly more detail, this client program
143
brings up network interfaces, uses the interfaces’ IPv6
144
link-local addresses to get network connectivity, uses Zeroconf
145
to find servers on the local network, and communicates with
146
servers using TLS with an OpenPGP key to ensure authenticity and
147
confidentiality. This client program keeps running, trying all
148
servers on the network, until it receives a satisfactory reply
149
or a TERM signal. After all servers have been tried, all
150
servers are periodically retried. If no servers are found it
151
will wait indefinitely for new servers to appear.
154
The network interfaces are selected like this: If any interfaces
155
are specified using the <option>--interface</option> option,
156
those interface are used. Otherwise,
157
<command>&COMMANDNAME;</command> will use all interfaces that
158
are not loopback interfaces, are not point-to-point interfaces,
159
are capable of broadcasting and do not have the NOARP flag (see
160
<citerefentry><refentrytitle>netdevice</refentrytitle>
161
<manvolnum>7</manvolnum></citerefentry>). (If the
162
<option>--connect</option> option is used, point-to-point
163
interfaces and non-broadcast interfaces are accepted.) If any
164
used interfaces are not up and running, they are first taken up
165
(and later taken down again on program exit).
168
Before network interfaces are selected, all <quote>network
169
hooks</quote> are run; see <xref linkend="network-hooks"/>.
172
This program is not meant to be run directly; it is really meant
173
to run as a plugin of the <application>Mandos</application>
174
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
175
<manvolnum>8mandos</manvolnum></citerefentry>, which runs in the
176
initial <acronym>RAM</acronym> disk environment because it is
177
specified as a <quote>keyscript</quote> in the <citerefentry>
178
<refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
179
</citerefentry> file.
183
<refsect1 id="purpose">
184
<title>PURPOSE</title>
186
The purpose of this is to enable <emphasis>remote and unattended
187
rebooting</emphasis> of client host computer with an
188
<emphasis>encrypted root file system</emphasis>. See <xref
189
linkend="overview"/> for details.
193
<refsect1 id="options">
194
<title>OPTIONS</title>
196
This program is commonly not invoked from the command line; it
197
is normally started by the <application>Mandos</application>
198
plugin runner, see <citerefentry><refentrytitle
199
>plugin-runner</refentrytitle><manvolnum>8mandos</manvolnum>
200
</citerefentry>. Any command line options this program accepts
201
are therefore normally provided by the plugin runner, and not
207
<term><option>--connect=<replaceable
208
>ADDRESS</replaceable><literal>:</literal><replaceable
209
>PORT</replaceable></option></term>
211
<replaceable>ADDRESS</replaceable><literal>:</literal
212
><replaceable>PORT</replaceable></option></term>
215
Do not use Zeroconf to locate servers. Connect directly
216
to only one specified <application>Mandos</application>
217
server. Note that an IPv6 address has colon characters in
218
it, so the <emphasis>last</emphasis> colon character is
219
assumed to separate the address from the port number.
222
Normally, Zeroconf would be used to locate Mandos servers,
223
in which case this option would only be used when testing
230
<term><option>--interface=<replaceable
231
>NAME</replaceable><arg rep='repeat'>,<replaceable
232
>NAME</replaceable></arg></option></term>
234
<replaceable>NAME</replaceable><arg rep='repeat'>,<replaceable
235
>NAME</replaceable></arg></option></term>
238
Comma separated list of network interfaces that will be
239
brought up and scanned for Mandos servers to connect to.
240
The default is the empty string, which will automatically
241
use all appropriate interfaces.
244
If the <option>--connect</option> option is used, and
245
exactly one interface name is specified (except
246
<quote><literal>none</literal></quote>), this specifies
247
the interface to use to connect to the address given.
250
Note that since this program will normally run in the
251
initial RAM disk environment, the interface must be an
252
interface which exists at that stage. Thus, the interface
253
can normally not be a pseudo-interface such as
254
<quote>br0</quote> or <quote>tun0</quote>; such interfaces
255
will not exist until much later in the boot process, and
256
can not be used by this program, unless created by a
257
<quote>network hook</quote> — see <xref
258
linkend="network-hooks"/>.
261
<replaceable>NAME</replaceable> can be the string
262
<quote><literal>none</literal></quote>; this will make
263
<command>&COMMANDNAME;</command> not bring up
264
<emphasis>any</emphasis> interfaces specified
265
<emphasis>after</emphasis> this string. This is not
266
recommended, and only meant for advanced users.
272
<term><option>--pubkey=<replaceable
273
>FILE</replaceable></option></term>
275
<replaceable>FILE</replaceable></option></term>
278
OpenPGP public key file name. The default name is
279
<quote><filename>/conf/conf.d/mandos/pubkey.txt</filename
286
<term><option>--seckey=<replaceable
287
>FILE</replaceable></option></term>
289
<replaceable>FILE</replaceable></option></term>
292
OpenPGP secret key file name. The default name is
293
<quote><filename>/conf/conf.d/mandos/seckey.txt</filename
300
<term><option>--priority=<replaceable
301
>STRING</replaceable></option></term>
303
<xi:include href="../mandos-options.xml"
304
xpointer="priority"/>
309
<term><option>--dh-bits=<replaceable
310
>BITS</replaceable></option></term>
313
Sets the number of bits to use for the prime number in the
314
TLS Diffie-Hellman key exchange. Default is 1024.
320
<term><option>--delay=<replaceable
321
>SECONDS</replaceable></option></term>
324
After bringing a network interface up, the program waits
325
for the interface to arrive in a <quote>running</quote>
326
state before proceeding. During this time, the kernel log
327
level will be lowered to reduce clutter on the system
328
console, alleviating any other plugins which might be
329
using the system console. This option sets the upper
330
limit of seconds to wait. The default is 2.5 seconds.
336
<term><option>--retry=<replaceable
337
>SECONDS</replaceable></option></term>
340
All Mandos servers are tried repeatedly until a password
341
is received. This value specifies, in seconds, how long
342
between each successive try <emphasis>for the same
343
server</emphasis>. The default is 10 seconds.
349
<term><option>--network-hook-dir=<replaceable
350
>DIR</replaceable></option></term>
353
Network hook directory. The default directory is
354
<quote><filename class="directory"
355
>/lib/mandos/network-hooks.d</filename></quote>.
361
<term><option>--debug</option></term>
364
Enable debug mode. This will enable a lot of output to
365
standard error about what the program is doing. The
366
program will still perform all other functions normally.
369
It will also enable debug mode in the Avahi and GnuTLS
370
libraries, making them print large amounts of debugging
377
<term><option>--help</option></term>
378
<term><option>-?</option></term>
381
Gives a help message about options and their meanings.
387
<term><option>--usage</option></term>
390
Gives a short usage message.
396
<term><option>--version</option></term>
397
<term><option>-V</option></term>
400
Prints the program version.
407
<refsect1 id="overview">
408
<title>OVERVIEW</title>
409
<xi:include href="../overview.xml"/>
411
This program is the client part. It is a plugin started by
412
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
413
<manvolnum>8mandos</manvolnum></citerefentry> which will run in
414
an initial <acronym>RAM</acronym> disk environment.
417
This program could, theoretically, be used as a keyscript in
418
<filename>/etc/crypttab</filename>, but it would then be
419
impossible to enter a password for the encrypted root disk at
420
the console, since this program does not read from the console
421
at all. This is why a separate plugin runner (<citerefentry>
422
<refentrytitle>plugin-runner</refentrytitle>
423
<manvolnum>8mandos</manvolnum></citerefentry>) is used to run
424
both this program and others in in parallel,
425
<emphasis>one</emphasis> of which (<citerefentry>
426
<refentrytitle>password-prompt</refentrytitle>
427
<manvolnum>8mandos</manvolnum></citerefentry>) will prompt for
428
passwords on the system console.
432
<refsect1 id="exit_status">
433
<title>EXIT STATUS</title>
435
This program will exit with a successful (zero) exit status if a
436
server could be found and the password received from it could be
437
successfully decrypted and output on standard output. The
438
program will exit with a non-zero exit status only if a critical
439
error occurs. Otherwise, it will forever connect to any
440
discovered <application>Mandos</application> servers, trying to
441
get a decryptable password and print it.
445
<refsect1 id="environment">
446
<title>ENVIRONMENT</title>
448
This program does not use any environment variables, not even
449
the ones provided by <citerefentry><refentrytitle
450
>cryptsetup</refentrytitle><manvolnum>8</manvolnum>
455
<refsect1 id="network-hooks">
456
<title>NETWORK HOOKS</title>
458
If a network interface like a bridge or tunnel is required to
459
find a Mandos server, this requires the interface to be up and
460
running before <command>&COMMANDNAME;</command> starts looking
461
for Mandos servers. This can be accomplished by creating a
462
<quote>network hook</quote> program, and placing it in a special
466
Before the network is used (and again before program exit), any
467
runnable programs found in the network hook directory are run
468
with the argument <quote><literal>start</literal></quote> or
469
<quote><literal>stop</literal></quote>. This should bring up or
470
down, respectively, any network interface which
471
<command>&COMMANDNAME;</command> should use.
473
<refsect2 id="hook-requirements">
474
<title>REQUIREMENTS</title>
476
A network hook must be an executable file, and its name must
477
consist entirely of upper and lower case letters, digits,
478
underscores, periods, and hyphens.
481
A network hook will receive one argument, which can be one of
486
<term><literal>start</literal></term>
489
This should make the network hook create (if necessary)
490
and bring up a network interface.
495
<term><literal>stop</literal></term>
498
This should make the network hook take down a network
499
interface, and delete it if it did not exist previously.
504
<term><literal>files</literal></term>
507
This should make the network hook print, <emphasis>one
508
file per line</emphasis>, all the files needed for it to
509
run. (These files will be copied into the initial RAM
510
filesystem.) Typical use is for a network hook which is
511
a shell script to print its needed binaries.
514
It is not necessary to print any non-executable files
515
already in the network hook directory, these will be
516
copied implicitly if they otherwise satisfy the name
522
<term><literal>modules</literal></term>
525
This should make the network hook print, <emphasis>on
526
separate lines</emphasis>, all the kernel modules needed
527
for it to run. (These modules will be copied into the
528
initial RAM filesystem.) For instance, a tunnel
530
<quote><literal>tun</literal></quote> module.
536
The network hook will be provided with a number of environment
541
<term><envar>MANDOSNETHOOKDIR</envar></term>
544
The network hook directory, specified to
545
<command>&COMMANDNAME;</command> by the
546
<option>--network-hook-dir</option> option. Note: this
547
should <emphasis>always</emphasis> be used by the
548
network hook to refer to itself or any files in the hook
549
directory it may require.
554
<term><envar>DEVICE</envar></term>
557
The network interfaces, as specified to
558
<command>&COMMANDNAME;</command> by the
559
<option>--interface</option> option, combined to one
560
string and separated by commas. If this is set, and
561
does not contain the interface a hook will bring up,
562
there is no reason for a hook to continue.
567
<term><envar>MODE</envar></term>
570
This will be the same as the first argument;
571
i.e. <quote><literal>start</literal></quote>,
572
<quote><literal>stop</literal></quote>,
573
<quote><literal>files</literal></quote>, or
574
<quote><literal>modules</literal></quote>.
579
<term><envar>VERBOSITY</envar></term>
582
This will be the <quote><literal>1</literal></quote> if
583
the <option>--debug</option> option is passed to
584
<command>&COMMANDNAME;</command>, otherwise
585
<quote><literal>0</literal></quote>.
590
<term><envar>DELAY</envar></term>
593
This will be the same as the <option>--delay</option>
594
option passed to <command>&COMMANDNAME;</command>. Is
595
only set if <envar>MODE</envar> is
596
<quote><literal>start</literal></quote> or
597
<quote><literal>stop</literal></quote>.
602
<term><envar>CONNECT</envar></term>
605
This will be the same as the <option>--connect</option>
606
option passed to <command>&COMMANDNAME;</command>. Is
607
only set if <option>--connect</option> is passed and
608
<envar>MODE</envar> is
609
<quote><literal>start</literal></quote> or
610
<quote><literal>stop</literal></quote>.
616
A hook may not read from standard input, and should be
617
restrictive in printing to standard output or standard error
618
unless <varname>VERBOSITY</varname> is
619
<quote><literal>1</literal></quote>.
624
<refsect1 id="files">
628
<term><filename>/conf/conf.d/mandos/pubkey.txt</filename
630
<term><filename>/conf/conf.d/mandos/seckey.txt</filename
634
OpenPGP public and private key files, in <quote>ASCII
635
Armor</quote> format. These are the default file names,
636
they can be changed with the <option>--pubkey</option> and
637
<option>--seckey</option> options.
643
class="directory">/lib/mandos/network-hooks.d</filename></term>
646
Directory where network hooks are located. Change this
647
with the <option>--network-hook-dir</option> option. See
648
<xref linkend="network-hooks"/>.
655
<!-- <refsect1 id="bugs"> -->
656
<!-- <title>BUGS</title> -->
661
<refsect1 id="example">
662
<title>EXAMPLE</title>
664
Note that normally, command line options will not be given
665
directly, but via options for the Mandos <citerefentry
666
><refentrytitle>plugin-runner</refentrytitle>
667
<manvolnum>8mandos</manvolnum></citerefentry>.
671
Normal invocation needs no options, if the network interfaces
672
can be automatically determined:
675
<userinput>&COMMANDNAME;</userinput>
680
Search for Mandos servers (and connect to them) using one
684
<!-- do not wrap this line -->
685
<userinput>&COMMANDNAME; --interface eth1</userinput>
690
Run in debug mode, and use a custom key:
694
<!-- do not wrap this line -->
695
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt</userinput>
701
Run in debug mode, with a custom key, and do not use Zeroconf
702
to locate a server; connect directly to the IPv6 link-local
703
address <quote><systemitem class="ipaddress"
704
>fe80::aede:48ff:fe71:f6f2</systemitem></quote>, port 4711,
705
using interface eth2:
709
<!-- do not wrap this line -->
710
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt --connect fe80::aede:48ff:fe71:f6f2:4711 --interface eth2</userinput>
716
<refsect1 id="security">
717
<title>SECURITY</title>
719
This program is set-uid to root, but will switch back to the
720
original (and presumably non-privileged) user and group after
721
bringing up the network interface.
724
To use this program for its intended purpose (see <xref
725
linkend="purpose"/>), the password for the root file system will
726
have to be given out to be stored in a server computer, after
727
having been encrypted using an OpenPGP key. This encrypted data
728
which will be stored in a server can only be decrypted by the
729
OpenPGP key, and the data will only be given out to those
730
clients who can prove they actually have that key. This key,
731
however, is stored unencrypted on the client side in its initial
732
<acronym>RAM</acronym> disk image file system. This is normally
733
readable by all, but this is normally fixed during installation
734
of this program; file permissions are set so that no-one is able
738
The only remaining weak point is that someone with physical
739
access to the client hard drive might turn off the client
740
computer, read the OpenPGP keys directly from the hard drive,
741
and communicate with the server. To safeguard against this, the
742
server is supposed to notice the client disappearing and stop
743
giving out the encrypted data. Therefore, it is important to
744
set the timeout and checker interval values tightly on the
745
server. See <citerefentry><refentrytitle
746
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
749
It will also help if the checker program on the server is
750
configured to request something from the client which can not be
751
spoofed by someone else on the network, unlike unencrypted
752
<acronym>ICMP</acronym> echo (<quote>ping</quote>) replies.
755
<emphasis>Note</emphasis>: This makes it completely insecure to
756
have <application >Mandos</application> clients which dual-boot
757
to another operating system which is <emphasis>not</emphasis>
758
trusted to keep the initial <acronym>RAM</acronym> disk image
763
<refsect1 id="see_also">
764
<title>SEE ALSO</title>
766
<citerefentry><refentrytitle>intro</refentrytitle>
767
<manvolnum>8mandos</manvolnum></citerefentry>,
768
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
769
<manvolnum>8</manvolnum></citerefentry>,
770
<citerefentry><refentrytitle>crypttab</refentrytitle>
771
<manvolnum>5</manvolnum></citerefentry>,
772
<citerefentry><refentrytitle>mandos</refentrytitle>
773
<manvolnum>8</manvolnum></citerefentry>,
774
<citerefentry><refentrytitle>password-prompt</refentrytitle>
775
<manvolnum>8mandos</manvolnum></citerefentry>,
776
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
777
<manvolnum>8mandos</manvolnum></citerefentry>
782
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
786
Zeroconf is the network protocol standard used for finding
787
Mandos servers on the local network.
793
<ulink url="http://www.avahi.org/">Avahi</ulink>
797
Avahi is the library this program calls to find Zeroconf
804
<ulink url="http://www.gnu.org/software/gnutls/"
809
GnuTLS is the library this client uses to implement TLS for
810
communicating securely with the server, and at the same time
811
send the public OpenPGP key to the server.
817
<ulink url="http://www.gnupg.org/related_software/gpgme/"
822
GPGME is the library used to decrypt the OpenPGP data sent
829
RFC 4291: <citetitle>IP Version 6 Addressing
830
Architecture</citetitle>
835
<term>Section 2.2: <citetitle>Text Representation of
836
Addresses</citetitle></term>
837
<listitem><para/></listitem>
840
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
841
Address</citetitle></term>
842
<listitem><para/></listitem>
845
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
846
Addresses</citetitle></term>
849
This client uses IPv6 link-local addresses, which are
850
immediately usable since a link-local addresses is
851
automatically assigned to a network interface when it
861
RFC 4346: <citetitle>The Transport Layer Security (TLS)
862
Protocol Version 1.1</citetitle>
866
TLS 1.1 is the protocol implemented by GnuTLS.
872
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
876
The data received from the server is binary encrypted
883
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
888
This is implemented by GnuTLS and used by this program so
889
that OpenPGP keys can be used.
897
<!-- Local Variables: -->
898
<!-- time-stamp-start: "<!ENTITY TIMESTAMP [\"']" -->
899
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900
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