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<refsect1 id="description">
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118
<title>DESCRIPTION</title>
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<command>&COMMANDNAME;</command> is a mandos plugin that works
151
like a client program that through avahi detects mandos servers,
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sets up a gnutls connect and request a encrypted password. Any
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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
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network connectivity, Zeroconf to find servers, and TLS with an
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OpenPGP key to ensure authenticity and confidentiality. It
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keeps running, trying all servers on the network, until it
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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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>PORT</replaceable></option></term>
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<replaceable>IPADDR</replaceable><literal>:</literal
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<replaceable>ADDRESS</replaceable><literal>:</literal
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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>-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
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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
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at all. This is why a separate plugin runner (<citerefentry>
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<refentrytitle>plugin-runner</refentrytitle>
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<manvolnum>8mandos</manvolnum></citerefentry>) is used to run
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both this program and others in in parallel,
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<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>
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This program will exit with a successful (zero) exit status if a
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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
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<application>Mandos</application> servers as they appear, trying
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to get a decryptable password and print it.
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<refsect1 id="environment">
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<title>ENVIRONMENT</title>
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This program does not use any environment variables, not even
340
the ones provided by <citerefentry><refentrytitle
341
>cryptsetup</refentrytitle><manvolnum>8</manvolnum>
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<refsect1 id="file">
301
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<title>FILES</title>
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<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
357
Armor</quote> format. These are the default file names,
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they can be changed with the <option>--pubkey</option> and
359
<option>--seckey</option> options.
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<!-- <refsect1 id="bugs"> -->
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<!-- <title>BUGS</title> -->
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<refsect1 id="example">
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<title>EXAMPLE</title>
375
Note that normally, command line options will not be given
376
directly, but via options for the Mandos <citerefentry
377
><refentrytitle>plugin-runner</refentrytitle>
378
<manvolnum>8mandos</manvolnum></citerefentry>.
382
Normal invocation needs no options, if the network interface
383
is <quote>eth0</quote>:
386
<userinput>&COMMANDNAME;</userinput>
391
Search for Mandos servers (and connect to them) using another
395
<!-- do not wrap this line -->
396
<userinput>&COMMANDNAME; --interface eth1</userinput>
401
Run in debug mode, and use a custom key:
405
<!-- do not wrap this line -->
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<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt</userinput>
412
Run in debug mode, with a custom key, and do not use Zeroconf
413
to locate a server; connect directly to the IPv6 address
414
<quote><systemitem class="ipaddress"
415
>2001:db8:f983:bd0b:30de:ae4a:71f2:f672</systemitem></quote>,
416
port 4711, using interface eth2:
420
<!-- do not wrap this line -->
421
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt --connect 2001:db8:f983:bd0b:30de:ae4a:71f2:f672:4711 --interface eth2</userinput>
318
427
<refsect1 id="security">
319
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<title>SECURITY</title>
430
This program is set-uid to root, but will switch back to the
431
original (and presumably non-privileged) user and group after
432
bringing up the network interface.
435
To use this program for its intended purpose (see <xref
436
linkend="purpose"/>), the password for the root file system will
437
have to be given out to be stored in a server computer, after
438
having been encrypted using an OpenPGP key. This encrypted data
439
which will be stored in a server can only be decrypted by the
440
OpenPGP key, and the data will only be given out to those
441
clients who can prove they actually have that key. This key,
442
however, is stored unencrypted on the client side in its initial
443
<acronym>RAM</acronym> disk image file system. This is normally
444
readable by all, but this is normally fixed during installation
445
of this program; file permissions are set so that no-one is able
449
The only remaining weak point is that someone with physical
450
access to the client hard drive might turn off the client
451
computer, read the OpenPGP keys directly from the hard drive,
452
and communicate with the server. The defense against this is
453
that the server is supposed to notice the client disappearing
454
and will stop giving out the encrypted data. Therefore, it is
455
important to set the timeout and checker interval values tightly
456
on the server. See <citerefentry><refentrytitle
457
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
460
It will also help if the checker program on the server is
461
configured to request something from the client which can not be
462
spoofed by someone else on the network, unlike unencrypted
463
<acronym>ICMP</acronym> echo (<quote>ping</quote>) replies.
466
<emphasis>Note</emphasis>: This makes it completely insecure to
467
have <application >Mandos</application> clients which dual-boot
468
to another operating system which is <emphasis>not</emphasis>
469
trusted to keep the initial <acronym>RAM</acronym> disk image
324
474
<refsect1 id="see_also">
325
475
<title>SEE ALSO</title>
477
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
478
<manvolnum>8</manvolnum></citerefentry>,
479
<citerefentry><refentrytitle>crypttab</refentrytitle>
480
<manvolnum>5</manvolnum></citerefentry>,
327
481
<citerefentry><refentrytitle>mandos</refentrytitle>
328
482
<manvolnum>8</manvolnum></citerefentry>,
329
483
<citerefentry><refentrytitle>password-prompt</refentrytitle>
331
485
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
332
486
<manvolnum>8mandos</manvolnum></citerefentry>
336
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
340
<ulink url="http://www.avahi.org/">Avahi</ulink>
345
url="http://www.gnu.org/software/gnutls/">GnuTLS</ulink>
350
url="http://www.gnupg.org/related_software/gpgme/">
355
<citation>RFC 4880: <citetitle>OpenPGP Message
356
Format</citetitle></citation>
360
<citation>RFC 5081: <citetitle>Using OpenPGP Keys for
361
Transport Layer Security</citetitle></citation>
365
<citation>RFC 4291: <citetitle>IP Version 6 Addressing
366
Architecture</citetitle>, section 2.5.6, Link-Local IPv6
367
Unicast Addresses</citation>
491
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
495
Zeroconf is the network protocol standard used for finding
496
Mandos servers on the local network.
502
<ulink url="http://www.avahi.org/">Avahi</ulink>
506
Avahi is the library this program calls to find Zeroconf
513
<ulink url="http://www.gnu.org/software/gnutls/"
518
GnuTLS is the library this client uses to implement TLS for
519
communicating securely with the server, and at the same time
520
send the public OpenPGP key to the server.
526
<ulink url="http://www.gnupg.org/related_software/gpgme/"
531
GPGME is the library used to decrypt the OpenPGP data sent
538
RFC 4291: <citetitle>IP Version 6 Addressing
539
Architecture</citetitle>
544
<term>Section 2.2: <citetitle>Text Representation of
545
Addresses</citetitle></term>
546
<listitem><para/></listitem>
549
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
550
Address</citetitle></term>
551
<listitem><para/></listitem>
554
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
555
Addresses</citetitle></term>
558
This client uses IPv6 link-local addresses, which are
559
immediately usable since a link-local addresses is
560
automatically assigned to a network interfaces when it
570
RFC 4346: <citetitle>The Transport Layer Security (TLS)
571
Protocol Version 1.1</citetitle>
575
TLS 1.1 is the protocol implemented by GnuTLS.
581
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
585
The data received from the server is binary encrypted
592
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
597
This is implemented by GnuTLS and used by this program so
598
that OpenPGP keys can be used.