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</refsynopsisdiv>
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<refsect1 id="description">
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119
<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
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<command>&COMMANDNAME;</command> is a client program that
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communicates with <citerefentry><refentrytitle
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>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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to get a password. It uses IPv6 link-local addresses to get
125
network connectivity, Zeroconf to find servers, and TLS with an
126
OpenPGP key to ensure authenticity and confidentiality. It
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keeps running, trying all servers on the network, until it
128
receives a satisfactory reply or a TERM signal is received.
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This program is not meant to be run directly; it is really meant
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to run as a plugin of the <application>Mandos</application>
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<citerefentry><refentrytitle>plugin-runner</refentrytitle>
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<manvolnum>8mandos</manvolnum></citerefentry>, which runs in the
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initial <acronym>RAM</acronym> disk environment because it is
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specified as a <quote>keyscript</quote> in the <citerefentry>
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<refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
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</citerefentry> file.
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<refsect1 id="purpose">
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<title>PURPOSE</title>
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The purpose of this is to enable <emphasis>remote and unattended
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rebooting</emphasis> of client host computer with an
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<emphasis>encrypted root file system</emphasis>. See <xref
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linkend="overview"/> for details.
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<refsect1 id="options">
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<title>OPTIONS</title>
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Commonly not invoked as command lines but from configuration
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file of plugin runner.
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This program is commonly not invoked from the command line; it
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is normally started by the <application>Mandos</application>
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plugin runner, see <citerefentry><refentrytitle
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>plugin-runner</refentrytitle><manvolnum>8mandos</manvolnum>
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</citerefentry>. Any command line options this program accepts
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are therefore normally provided by the plugin runner, and not
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<term><option>--connect=<replaceable
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>IPADDR</replaceable><literal>:</literal><replaceable
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>ADDRESS</replaceable><literal>:</literal><replaceable
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168
>PORT</replaceable></option></term>
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<replaceable>IPADDR</replaceable><literal>:</literal
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<replaceable>ADDRESS</replaceable><literal>:</literal
149
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><replaceable>PORT</replaceable></option></term>
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Connect directly to a specified mandos server
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Do not use Zeroconf to locate servers. Connect directly
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to only one specified <application>Mandos</application>
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server. Note that an IPv6 address has colon characters in
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it, so the <emphasis>last</emphasis> colon character is
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assumed to separate the address from the port number.
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<term><option>--keydir=<replaceable
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>DIRECTORY</replaceable></option></term>
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<replaceable>DIRECTORY</replaceable></option></term>
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Directory where the openpgp keyring is
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This option is normally only useful for testing and
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<term><option>--interface=
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<replaceable>NAME</replaceable></option></term>
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<term><option>--usage</option></term>
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Gives a short usage message
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Gives a short usage message.
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<term><option>--version</option></term>
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<term><option>-V</option></term>
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Prints the program version
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Prints the program version.
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<refsect1 id="overview">
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<title>OVERVIEW</title>
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<xi:include href="../overview.xml"/>
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This program is the client part. It is a plugin started by
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<citerefentry><refentrytitle>plugin-runner</refentrytitle>
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<manvolnum>8mandos</manvolnum></citerefentry> which will run in
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an initial <acronym>RAM</acronym> disk environment.
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This program could, theoretically, be used as a keyscript in
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<filename>/etc/crypttab</filename>, but it would then be
313
impossible to enter a password for the encrypted root disk at
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the console, since this program does not read from the console
315
at all. This is why a separate plugin runner (<citerefentry>
316
<refentrytitle>plugin-runner</refentrytitle>
317
<manvolnum>8mandos</manvolnum></citerefentry>) is used to run
318
both this program and others in in parallel,
319
<emphasis>one</emphasis> of which will prompt for passwords on
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<refsect1 id="exit_status">
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<title>EXIT STATUS</title>
327
This program will exit with a successful (zero) exit status if a
328
server could be found and the password received from it could be
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successfully decrypted and output on standard output. The
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program will exit with a non-zero exit status only if a critical
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error occurs. Otherwise, it will forever connect to new
332
<application>Mandos</application> servers as they appear, trying
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to get a decryptable password and print it.
271
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<refsect1 id="environment">
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<title>ENVIRONMENT</title>
340
This program does not use any environment variables, not even
341
the ones provided by <citerefentry><refentrytitle
342
>cryptsetup</refentrytitle><manvolnum>8</manvolnum>
277
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<refsect1 id="file">
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<title>FILES</title>
351
<term><filename>/conf/conf.d/mandos/pubkey.txt</filename
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<term><filename>/conf/conf.d/mandos/seckey.txt</filename
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OpenPGP public and private key files, in <quote>ASCII
358
Armor</quote> format. These are the default file names,
359
they can be changed with the <option>--pubkey</option> and
360
<option>--seckey</option> options.
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<!-- <refsect1 id="bugs"> -->
368
<!-- <title>BUGS</title> -->
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<refsect1 id="example">
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<title>EXAMPLE</title>
376
Note that normally, command line options will not be given
377
directly, but via options for the Mandos <citerefentry
378
><refentrytitle>plugin-runner</refentrytitle>
379
<manvolnum>8mandos</manvolnum></citerefentry>.
383
Normal invocation needs no options, if the network interface
384
is <quote>eth0</quote>:
387
<userinput>&COMMANDNAME;</userinput>
392
Search for Mandos servers (and connect to them) using another
396
<!-- do not wrap this line -->
397
<userinput>&COMMANDNAME; --interface eth1</userinput>
402
Run in debug mode, and use a custom key:
406
<!-- do not wrap this line -->
407
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt</userinput>
413
Run in debug mode, with a custom key, and do not use Zeroconf
414
to locate a server; connect directly to the IPv6 address
415
<quote><systemitem class="ipaddress"
416
>2001:db8:f983:bd0b:30de:ae4a:71f2:f672</systemitem></quote>,
417
port 4711, using interface eth2:
421
<!-- do not wrap this line -->
422
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt --connect 2001:db8:f983:bd0b:30de:ae4a:71f2:f672:4711 --interface eth2</userinput>
295
428
<refsect1 id="security">
296
429
<title>SECURITY</title>
431
This program is set-uid to root, but will switch back to the
432
original (and presumably non-privileged) user and group after
433
bringing up the network interface.
436
To use this program for its intended purpose (see <xref
437
linkend="purpose"/>), the password for the root file system will
438
have to be given out to be stored in a server computer, after
439
having been encrypted using an OpenPGP key. This encrypted data
440
which will be stored in a server can only be decrypted by the
441
OpenPGP key, and the data will only be given out to those
442
clients who can prove they actually have that key. This key,
443
however, is stored unencrypted on the client side in its initial
444
<acronym>RAM</acronym> disk image file system. This is normally
445
readable by all, but this is normally fixed during installation
446
of this program; file permissions are set so that no-one is able
450
The only remaining weak point is that someone with physical
451
access to the client hard drive might turn off the client
452
computer, read the OpenPGP keys directly from the hard drive,
453
and communicate with the server. To safeguard against this, the
454
server is supposed to notice the client disappearing and stop
455
giving out the encrypted data. Therefore, it is important to
456
set the timeout and checker interval values tightly on the
457
server. See <citerefentry><refentrytitle
458
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
461
It will also help if the checker program on the server is
462
configured to request something from the client which can not be
463
spoofed by someone else on the network, unlike unencrypted
464
<acronym>ICMP</acronym> echo (<quote>ping</quote>) replies.
467
<emphasis>Note</emphasis>: This makes it completely insecure to
468
have <application >Mandos</application> clients which dual-boot
469
to another operating system which is <emphasis>not</emphasis>
470
trusted to keep the initial <acronym>RAM</acronym> disk image
301
475
<refsect1 id="see_also">
302
476
<title>SEE ALSO</title>
478
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
479
<manvolnum>8</manvolnum></citerefentry>,
480
<citerefentry><refentrytitle>crypttab</refentrytitle>
481
<manvolnum>5</manvolnum></citerefentry>,
304
482
<citerefentry><refentrytitle>mandos</refentrytitle>
305
483
<manvolnum>8</manvolnum></citerefentry>,
306
484
<citerefentry><refentrytitle>password-prompt</refentrytitle>
308
486
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
309
487
<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>
492
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
496
Zeroconf is the network protocol standard used for finding
497
Mandos servers on the local network.
503
<ulink url="http://www.avahi.org/">Avahi</ulink>
507
Avahi is the library this program calls to find Zeroconf
514
<ulink url="http://www.gnu.org/software/gnutls/"
519
GnuTLS is the library this client uses to implement TLS for
520
communicating securely with the server, and at the same time
521
send the public OpenPGP key to the server.
527
<ulink url="http://www.gnupg.org/related_software/gpgme/"
532
GPGME is the library used to decrypt the OpenPGP data sent
539
RFC 4291: <citetitle>IP Version 6 Addressing
540
Architecture</citetitle>
545
<term>Section 2.2: <citetitle>Text Representation of
546
Addresses</citetitle></term>
547
<listitem><para/></listitem>
550
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
551
Address</citetitle></term>
552
<listitem><para/></listitem>
555
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
556
Addresses</citetitle></term>
559
This client uses IPv6 link-local addresses, which are
560
immediately usable since a link-local addresses is
561
automatically assigned to a network interfaces when it
571
RFC 4346: <citetitle>The Transport Layer Security (TLS)
572
Protocol Version 1.1</citetitle>
576
TLS 1.1 is the protocol implemented by GnuTLS.
582
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
586
The data received from the server is binary encrypted
593
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
598
This is implemented by GnuTLS and used by this program so
599
that OpenPGP keys can be used.
350
607
<!-- Local Variables: -->
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<!-- time-stamp-start: "<!ENTITY TIMESTAMP [\"']" -->
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<!-- time-stamp-end: "[\"']>" -->