122
131
</refsynopsisdiv>
124
133
<refsect1 id="description">
125
134
<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
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.
135
192
<refsect1 id="options">
136
193
<title>OPTIONS</title>
138
Commonly not invoked as command lines but from configuration
139
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
144
206
<term><option>--connect=<replaceable
145
>IPADDR</replaceable><literal>:</literal><replaceable
207
>ADDRESS</replaceable><literal>:</literal><replaceable
146
208
>PORT</replaceable></option></term>
148
<replaceable>IPADDR</replaceable><literal>:</literal
210
<replaceable>ADDRESS</replaceable><literal>:</literal
149
211
><replaceable>PORT</replaceable></option></term>
152
Connect directly to a specified mandos server
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.
158
<term><option>--keydir=<replaceable
159
>DIRECTORY</replaceable></option></term>
161
<replaceable>DIRECTORY</replaceable></option></term>
164
Directory where the openpgp keyring is
221
This option is normally only useful for testing and
170
<term><option>--interface=
171
<replaceable>NAME</replaceable></option></term>
228
<term><option>--interface=<replaceable
229
>NAME</replaceable></option></term>
173
231
<replaceable>NAME</replaceable></option></term>
176
Interface that Avahi will connect through
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
182
265
<term><option>--pubkey=<replaceable
183
266
>FILE</replaceable></option></term>
245
380
<term><option>--usage</option></term>
248
Gives a short usage message
383
Gives a short usage message.
254
389
<term><option>--version</option></term>
255
390
<term><option>-V</option></term>
258
Prints the program version
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.
265
425
<refsect1 id="exit_status">
266
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.
271
438
<refsect1 id="environment">
272
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, 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>on
501
separate lines</emphasis>, all the files needed for it
502
to run. (These files will be copied into the initial
503
RAM filesystem.) Intended use is for a network hook
504
which is 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
516
The network hook will be provided with a number of environment
521
<term><envar>MANDOSNETHOOKDIR</envar></term>
524
The network hook directory, specified to
525
<command>&COMMANDNAME;</command> by the
526
<option>--network-hook-dir</option> option. Note: this
527
should <emphasis>always</emphasis> be used by the
528
network hook to refer to itself or any files it may
534
<term><envar>DEVICE</envar></term>
537
The network interface, as specified to
538
<command>&COMMANDNAME;</command> by the
539
<option>--interface</option> option. If this is not the
540
interface a hook will bring up, there is no reason for a
546
<term><envar>MODE</envar></term>
549
This will be the same as the first argument;
550
i.e. <quote><literal>start</literal></quote>,
551
<quote><literal>stop</literal></quote>, or
552
<quote><literal>files</literal></quote>.
557
<term><envar>VERBOSITY</envar></term>
560
This will be the <quote><literal>1</literal></quote> if
561
the <option>--debug</option> option is passed to
562
<command>&COMMANDNAME;</command>, otherwise
563
<quote><literal>0</literal></quote>.
568
<term><envar>DELAY</envar></term>
571
This will be the same as the <option>--delay</option>
572
option passed to <command>&COMMANDNAME;</command>.
578
A hook may not read from standard input, and should be
579
restrictive in printing to standard output or standard error
580
unless <varname>VERBOSITY</varname> is
581
<quote><literal>1</literal></quote>.
586
<refsect1 id="files">
278
587
<title>FILES</title>
590
<term><filename>/conf/conf.d/mandos/pubkey.txt</filename
592
<term><filename>/conf/conf.d/mandos/seckey.txt</filename
596
OpenPGP public and private key files, in <quote>ASCII
597
Armor</quote> format. These are the default file names,
598
they can be changed with the <option>--pubkey</option> and
599
<option>--seckey</option> options.
605
class="directory">/lib/mandos/network-hooks.d</filename></term>
608
Directory where network hooks are located. Change this
609
with the <option>--network-hook-dir</option> option. See
610
<xref linkend="network-hooks"/>.
617
<!-- <refsect1 id="bugs"> -->
618
<!-- <title>BUGS</title> -->
289
623
<refsect1 id="example">
290
624
<title>EXAMPLE</title>
626
Note that normally, command line options will not be given
627
directly, but via options for the Mandos <citerefentry
628
><refentrytitle>plugin-runner</refentrytitle>
629
<manvolnum>8mandos</manvolnum></citerefentry>.
633
Normal invocation needs no options, if the network interface
634
is <quote>eth0</quote>:
637
<userinput>&COMMANDNAME;</userinput>
642
Search for Mandos servers (and connect to them) using another
646
<!-- do not wrap this line -->
647
<userinput>&COMMANDNAME; --interface eth1</userinput>
652
Run in debug mode, and use a custom key:
656
<!-- do not wrap this line -->
657
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt</userinput>
663
Run in debug mode, with a custom key, and do not use Zeroconf
664
to locate a server; connect directly to the IPv6 link-local
665
address <quote><systemitem class="ipaddress"
666
>fe80::aede:48ff:fe71:f6f2</systemitem></quote>, port 4711,
667
using interface eth2:
671
<!-- do not wrap this line -->
672
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt --connect fe80::aede:48ff:fe71:f6f2:4711 --interface eth2</userinput>
295
678
<refsect1 id="security">
296
679
<title>SECURITY</title>
681
This program is set-uid to root, but will switch back to the
682
original (and presumably non-privileged) user and group after
683
bringing up the network interface.
686
To use this program for its intended purpose (see <xref
687
linkend="purpose"/>), the password for the root file system will
688
have to be given out to be stored in a server computer, after
689
having been encrypted using an OpenPGP key. This encrypted data
690
which will be stored in a server can only be decrypted by the
691
OpenPGP key, and the data will only be given out to those
692
clients who can prove they actually have that key. This key,
693
however, is stored unencrypted on the client side in its initial
694
<acronym>RAM</acronym> disk image file system. This is normally
695
readable by all, but this is normally fixed during installation
696
of this program; file permissions are set so that no-one is able
700
The only remaining weak point is that someone with physical
701
access to the client hard drive might turn off the client
702
computer, read the OpenPGP keys directly from the hard drive,
703
and communicate with the server. To safeguard against this, the
704
server is supposed to notice the client disappearing and stop
705
giving out the encrypted data. Therefore, it is important to
706
set the timeout and checker interval values tightly on the
707
server. See <citerefentry><refentrytitle
708
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
711
It will also help if the checker program on the server is
712
configured to request something from the client which can not be
713
spoofed by someone else on the network, unlike unencrypted
714
<acronym>ICMP</acronym> echo (<quote>ping</quote>) replies.
717
<emphasis>Note</emphasis>: This makes it completely insecure to
718
have <application >Mandos</application> clients which dual-boot
719
to another operating system which is <emphasis>not</emphasis>
720
trusted to keep the initial <acronym>RAM</acronym> disk image
301
725
<refsect1 id="see_also">
302
726
<title>SEE ALSO</title>
728
<citerefentry><refentrytitle>intro</refentrytitle>
729
<manvolnum>8mandos</manvolnum></citerefentry>,
730
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
731
<manvolnum>8</manvolnum></citerefentry>,
732
<citerefentry><refentrytitle>crypttab</refentrytitle>
733
<manvolnum>5</manvolnum></citerefentry>,
304
734
<citerefentry><refentrytitle>mandos</refentrytitle>
305
735
<manvolnum>8</manvolnum></citerefentry>,
306
736
<citerefentry><refentrytitle>password-prompt</refentrytitle>
308
738
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
309
739
<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>
744
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
748
Zeroconf is the network protocol standard used for finding
749
Mandos servers on the local network.
755
<ulink url="http://www.avahi.org/">Avahi</ulink>
759
Avahi is the library this program calls to find Zeroconf
766
<ulink url="http://www.gnu.org/software/gnutls/"
771
GnuTLS is the library this client uses to implement TLS for
772
communicating securely with the server, and at the same time
773
send the public OpenPGP key to the server.
779
<ulink url="http://www.gnupg.org/related_software/gpgme/"
784
GPGME is the library used to decrypt the OpenPGP data sent
791
RFC 4291: <citetitle>IP Version 6 Addressing
792
Architecture</citetitle>
797
<term>Section 2.2: <citetitle>Text Representation of
798
Addresses</citetitle></term>
799
<listitem><para/></listitem>
802
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
803
Address</citetitle></term>
804
<listitem><para/></listitem>
807
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
808
Addresses</citetitle></term>
811
This client uses IPv6 link-local addresses, which are
812
immediately usable since a link-local addresses is
813
automatically assigned to a network interfaces when it
823
RFC 4346: <citetitle>The Transport Layer Security (TLS)
824
Protocol Version 1.1</citetitle>
828
TLS 1.1 is the protocol implemented by GnuTLS.
834
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
838
The data received from the server is binary encrypted
845
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
850
This is implemented by GnuTLS and used by this program so
851
that OpenPGP keys can be used.
350
859
<!-- Local Variables: -->
351
860
<!-- time-stamp-start: "<!ENTITY TIMESTAMP [\"']" -->
352
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<!-- time-stamp-end: "[\"']>" -->