122
135
</refsynopsisdiv>
124
137
<refsect1 id="description">
125
138
<title>DESCRIPTION</title>
127
<command>&COMMANDNAME;</command> is a mandos plugin that works
128
like a client program that through avahi detects mandos servers,
129
sets up a gnutls connect and request a encrypted password. Any
130
passwords given is automaticly decrypted and passed to
140
<command>&COMMANDNAME;</command> is a client program that
141
communicates with <citerefentry><refentrytitle
142
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>
143
to get a password. In slightly more detail, this client program
144
brings up network interfaces, uses the interfaces’ IPv6
145
link-local addresses to get network connectivity, uses Zeroconf
146
to find servers on the local network, and communicates with
147
servers using TLS with an OpenPGP key to ensure authenticity and
148
confidentiality. This client program keeps running, trying all
149
servers on the network, until it receives a satisfactory reply
150
or a TERM signal. After all servers have been tried, all
151
servers are periodically retried. If no servers are found it
152
will wait indefinitely for new servers to appear.
155
The network interfaces are selected like this: If any interfaces
156
are specified using the <option>--interface</option> option,
157
those interface are used. Otherwise,
158
<command>&COMMANDNAME;</command> will use all interfaces that
159
are not loopback interfaces, are not point-to-point interfaces,
160
are capable of broadcasting and do not have the NOARP flag (see
161
<citerefentry><refentrytitle>netdevice</refentrytitle>
162
<manvolnum>7</manvolnum></citerefentry>). (If the
163
<option>--connect</option> option is used, point-to-point
164
interfaces and non-broadcast interfaces are accepted.) If any
165
used interfaces are not up and running, they are first taken up
166
(and later taken down again on program exit).
169
Before network interfaces are selected, all <quote>network
170
hooks</quote> are run; see <xref linkend="network-hooks"/>.
173
This program is not meant to be run directly; it is really meant
174
to run as a plugin of the <application>Mandos</application>
175
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
176
<manvolnum>8mandos</manvolnum></citerefentry>, which runs in the
177
initial <acronym>RAM</acronym> disk environment because it is
178
specified as a <quote>keyscript</quote> in the <citerefentry>
179
<refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
180
</citerefentry> file.
184
<refsect1 id="purpose">
185
<title>PURPOSE</title>
187
The purpose of this is to enable <emphasis>remote and unattended
188
rebooting</emphasis> of client host computer with an
189
<emphasis>encrypted root file system</emphasis>. See <xref
190
linkend="overview"/> for details.
135
194
<refsect1 id="options">
136
195
<title>OPTIONS</title>
138
Commonly not invoked as command lines but from configuration
139
file of plugin runner.
197
This program is commonly not invoked from the command line; it
198
is normally started by the <application>Mandos</application>
199
plugin runner, see <citerefentry><refentrytitle
200
>plugin-runner</refentrytitle><manvolnum>8mandos</manvolnum>
201
</citerefentry>. Any command line options this program accepts
202
are therefore normally provided by the plugin runner, and not
144
208
<term><option>--connect=<replaceable
145
>IPADDR</replaceable><literal>:</literal><replaceable
209
>ADDRESS</replaceable><literal>:</literal><replaceable
146
210
>PORT</replaceable></option></term>
148
<replaceable>IPADDR</replaceable><literal>:</literal
212
<replaceable>ADDRESS</replaceable><literal>:</literal
149
213
><replaceable>PORT</replaceable></option></term>
152
Connect directly to a specified mandos server
216
Do not use Zeroconf to locate servers. Connect directly
217
to only one specified <application>Mandos</application>
218
server. Note that an IPv6 address has colon characters in
219
it, so the <emphasis>last</emphasis> colon character is
220
assumed to separate the address from the port number.
158
<term><option>--keydir=<replaceable
159
>DIRECTORY</replaceable></option></term>
161
<replaceable>DIRECTORY</replaceable></option></term>
164
Directory where the openpgp keyring is
223
Normally, Zeroconf would be used to locate Mandos servers,
224
in which case this option would only be used when testing
170
<term><option>--interface=
171
<replaceable>NAME</replaceable></option></term>
231
<term><option>--interface=<replaceable
232
>NAME</replaceable><arg rep='repeat'>,<replaceable
233
>NAME</replaceable></arg></option></term>
173
<replaceable>NAME</replaceable></option></term>
235
<replaceable>NAME</replaceable><arg rep='repeat'>,<replaceable
236
>NAME</replaceable></arg></option></term>
176
Interface that Avahi will connect through
239
Comma separated list of network interfaces that will be
240
brought up and scanned for Mandos servers to connect to.
241
The default is the empty string, which will automatically
242
use all appropriate interfaces.
245
If the <option>--connect</option> option is used, and
246
exactly one interface name is specified (except
247
<quote><literal>none</literal></quote>), this specifies
248
the interface to use to connect to the address given.
251
Note that since this program will normally run in the
252
initial RAM disk environment, the interface must be an
253
interface which exists at that stage. Thus, the interface
254
can normally not be a pseudo-interface such as
255
<quote>br0</quote> or <quote>tun0</quote>; such interfaces
256
will not exist until much later in the boot process, and
257
can not be used by this program, unless created by a
258
<quote>network hook</quote> — see <xref
259
linkend="network-hooks"/>.
262
<replaceable>NAME</replaceable> can be the string
263
<quote><literal>none</literal></quote>; this will make
264
<command>&COMMANDNAME;</command> only bring up interfaces
265
specified <emphasis>before</emphasis> this string. This
266
is not recommended, and only meant for advanced users.
182
272
<term><option>--pubkey=<replaceable
183
273
>FILE</replaceable></option></term>
245
387
<term><option>--usage</option></term>
248
Gives a short usage message
390
Gives a short usage message.
254
396
<term><option>--version</option></term>
255
397
<term><option>-V</option></term>
258
Prints the program version
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.
265
432
<refsect1 id="exit_status">
266
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.
271
445
<refsect1 id="environment">
272
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">
278
625
<title>FILES</title>
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> -->
289
661
<refsect1 id="example">
290
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>
295
716
<refsect1 id="security">
296
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, like SSH server key
752
fingerprints, and unlike unencrypted <acronym>ICMP</acronym>
753
echo (<quote>ping</quote>) replies.
756
<emphasis>Note</emphasis>: This makes it completely insecure to
757
have <application >Mandos</application> clients which dual-boot
758
to another operating system which is <emphasis>not</emphasis>
759
trusted to keep the initial <acronym>RAM</acronym> disk image
301
764
<refsect1 id="see_also">
302
765
<title>SEE ALSO</title>
767
<citerefentry><refentrytitle>intro</refentrytitle>
768
<manvolnum>8mandos</manvolnum></citerefentry>,
769
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
770
<manvolnum>8</manvolnum></citerefentry>,
771
<citerefentry><refentrytitle>crypttab</refentrytitle>
772
<manvolnum>5</manvolnum></citerefentry>,
304
773
<citerefentry><refentrytitle>mandos</refentrytitle>
305
774
<manvolnum>8</manvolnum></citerefentry>,
306
775
<citerefentry><refentrytitle>password-prompt</refentrytitle>
308
777
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
309
778
<manvolnum>8mandos</manvolnum></citerefentry>
313
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
317
<ulink url="http://www.avahi.org/">Avahi</ulink>
322
url="http://www.gnu.org/software/gnutls/">GnuTLS</ulink>
327
url="http://www.gnupg.org/related_software/gpgme/">
332
<citation>RFC 4880: <citetitle>OpenPGP Message
333
Format</citetitle></citation>
337
<citation>RFC 5081: <citetitle>Using OpenPGP Keys for
338
Transport Layer Security</citetitle></citation>
342
<citation>RFC 4291: <citetitle>IP Version 6 Addressing
343
Architecture</citetitle>, section 2.5.6, Link-Local IPv6
344
Unicast Addresses</citation>
783
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
787
Zeroconf is the network protocol standard used for finding
788
Mandos servers on the local network.
794
<ulink url="http://www.avahi.org/">Avahi</ulink>
798
Avahi is the library this program calls to find Zeroconf
805
<ulink url="http://www.gnu.org/software/gnutls/"
810
GnuTLS is the library this client uses to implement TLS for
811
communicating securely with the server, and at the same time
812
send the public OpenPGP key to the server.
818
<ulink url="http://www.gnupg.org/related_software/gpgme/"
823
GPGME is the library used to decrypt the OpenPGP data sent
830
RFC 4291: <citetitle>IP Version 6 Addressing
831
Architecture</citetitle>
836
<term>Section 2.2: <citetitle>Text Representation of
837
Addresses</citetitle></term>
838
<listitem><para/></listitem>
841
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
842
Address</citetitle></term>
843
<listitem><para/></listitem>
846
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
847
Addresses</citetitle></term>
850
This client uses IPv6 link-local addresses, which are
851
immediately usable since a link-local addresses is
852
automatically assigned to a network interface when it
862
RFC 4346: <citetitle>The Transport Layer Security (TLS)
863
Protocol Version 1.1</citetitle>
867
TLS 1.1 is the protocol implemented by GnuTLS.
873
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
877
The data received from the server is binary encrypted
884
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
889
This is implemented by GnuTLS and used by this program so
890
that OpenPGP keys can be used.
350
898
<!-- Local Variables: -->
351
899
<!-- time-stamp-start: "<!ENTITY TIMESTAMP [\"']" -->
352
900
<!-- time-stamp-end: "[\"']>" -->