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<refname><command>&COMMANDNAME;</command></refname>
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Client for <application>Mandos</application>
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<command>&COMMANDNAME;</command>
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<arg choice="plain"><option>--connect
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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></arg>
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<arg choice="plain"><option>-c
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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></arg>
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<arg choice="plain"><option>--keydir
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<replaceable>DIRECTORY</replaceable></option></arg>
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<arg choice="plain"><option>-d
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<replaceable>DIRECTORY</replaceable></option></arg>
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<arg choice="plain"><option>--interface
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<replaceable>NAME</replaceable></option></arg>
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<arg choice="plain"><option>-i
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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 the server, and TLS with
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an OpenPGP key to ensure authenticity and confidentiality. It
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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.
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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 in turn
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runs as a <quote>keyscript</quote> specified in the
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<citerefentry><refentrytitle>crypttab</refentrytitle>
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<manvolnum>5</manvolnum></citerefentry> file.
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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="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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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>Mandosservers</application> servers as they appear,
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trying to get a decryptable password.
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<!-- <refsect1 id="environment"> -->
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<!-- <title>ENVIRONMENT</title> -->
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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
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the ones provided by <citerefentry><refentrytitle
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>cryptsetup</refentrytitle><manvolnum>8</manvolnum>
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<refsect1 id="files">
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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
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Armor</quote> format. These are the default file names,
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they can be changed with the <option>--pubkey</option> and
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<option>--seckey</option> options.
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<!-- <refsect1 id="bugs"> -->
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<!-- <title>BUGS</title> -->
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<!-- This program does not use any environment variables. -->
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<!-- </refsect1> -->
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<refsect1 id="example">
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<title>EXAMPLE</title>
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Note that normally, command line options will not be given
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directly, but via options for the Mandos <citerefentry
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><refentrytitle>plugin-runner</refentrytitle>
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<manvolnum>8mandos</manvolnum></citerefentry>.
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Normal invocation needs no options, if the network interface
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is <quote>eth0</quote>:
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<userinput>&COMMANDNAME;</userinput>
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Search for Mandos servers (and connect to them) using another
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<!-- do not wrap this line -->
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<userinput>&COMMANDNAME; --interface eth1</userinput>
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Run in debug mode, and use a custom key:
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<!-- do not wrap this line -->
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<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt</userinput>
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Run in debug mode, with a custom key, and do not use Zeroconf
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to locate a server; connect directly to the IPv6 address
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<quote><systemitem class="ipaddress"
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>2001:db8:f983:bd0b:30de:ae4a:71f2:f672</systemitem></quote>,
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port 4711, using interface eth2:
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<!-- do not wrap this line -->
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<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt --connect 2001:db8:f983:bd0b:30de:ae4a:71f2:f672:4711 --interface eth2</userinput>
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<refsect1 id="security">
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<title>SECURITY</title>
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This program is set-uid to root, but will switch back to the
433
original (and presumably non-privileged) user and group after
434
bringing up the network interface.
437
To use this program for its intended purpose (see <xref
438
linkend="purpose"/>), the password for the root file system will
439
have to be given out to be stored in a server computer, after
440
having been encrypted using an OpenPGP key. This encrypted data
441
which will be stored in a server can only be decrypted by the
442
OpenPGP key, and the data will only be given out to those
443
clients who can prove they actually have that key. This key,
444
however, is stored unencrypted on the client side in its initial
445
<acronym>RAM</acronym> disk image file system. This is normally
446
readable by all, but this is normally fixed during installation
447
of this program; file permissions are set so that no-one is able
451
The only remaining weak point is that someone with physical
452
access to the client hard drive might turn off the client
453
computer, read the OpenPGP keys directly from the hard drive,
454
and communicate with the server. To safeguard against this, the
455
server is supposed to notice the client disappearing and stop
456
giving out the encrypted data. Therefore, it is important to
457
set the timeout and checker interval values tightly on the
458
server. See <citerefentry><refentrytitle
459
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
462
It will also help if the checker program on the server is
463
configured to request something from the client which can not be
464
spoofed by someone else on the network, unlike unencrypted
465
<acronym>ICMP</acronym> echo (<quote>ping</quote>) replies.
468
<emphasis>Note</emphasis>: This makes it completely insecure to
469
have <application >Mandos</application> clients which dual-boot
470
to another operating system which is <emphasis>not</emphasis>
471
trusted to keep the initial <acronym>RAM</acronym> disk image
380
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<refsect1 id="see_also">
381
477
<title>SEE ALSO</title>
479
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
480
<manvolnum>8</manvolnum></citerefentry>,
481
<citerefentry><refentrytitle>crypttab</refentrytitle>
482
<manvolnum>5</manvolnum></citerefentry>,
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483
<citerefentry><refentrytitle>mandos</refentrytitle>
384
484
<manvolnum>8</manvolnum></citerefentry>,
385
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<citerefentry><refentrytitle>password-prompt</refentrytitle>
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<citerefentry><refentrytitle>plugin-runner</refentrytitle>
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<manvolnum>8mandos</manvolnum></citerefentry>
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<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
396
<ulink url="http://www.avahi.org/">Avahi</ulink>
401
url="http://www.gnu.org/software/gnutls/">GnuTLS</ulink>
406
url="http://www.gnupg.org/related_software/gpgme/">
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<citation>RFC 4880: <citetitle>OpenPGP Message
412
Format</citetitle></citation>
416
<citation>RFC 5081: <citetitle>Using OpenPGP Keys for
417
Transport Layer Security</citetitle></citation>
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<citation>RFC 4291: <citetitle>IP Version 6 Addressing
422
Architecture</citetitle>, section 2.5.6, Link-Local IPv6
423
Unicast Addresses</citation>
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<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
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Zeroconf is the network protocol standard used for finding
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Mandos servers on the local network.
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<ulink url="http://www.avahi.org/">Avahi</ulink>
508
Avahi is the library this program calls to find Zeroconf
515
<ulink url="http://www.gnu.org/software/gnutls/"
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GnuTLS is the library this client uses to implement TLS for
521
communicating securely with the server, and at the same time
522
send the public OpenPGP key to the server.
528
<ulink url="http://www.gnupg.org/related_software/gpgme/"
533
GPGME is the library used to decrypt the OpenPGP data sent
540
RFC 4291: <citetitle>IP Version 6 Addressing
541
Architecture</citetitle>
546
<term>Section 2.2: <citetitle>Text Representation of
547
Addresses</citetitle></term>
548
<listitem><para/></listitem>
551
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
552
Address</citetitle></term>
553
<listitem><para/></listitem>
556
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
557
Addresses</citetitle></term>
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This client uses IPv6 link-local addresses, which are
561
immediately usable since a link-local addresses is
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automatically assigned to a network interfaces when it
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RFC 4346: <citetitle>The Transport Layer Security (TLS)
573
Protocol Version 1.1</citetitle>
577
TLS 1.1 is the protocol implemented by GnuTLS.
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RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
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The data received from the server is binary encrypted
594
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
599
This is implemented by GnuTLS and used by this program so
600
that OpenPGP keys can be used.
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<!-- Local Variables: -->
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<!-- time-stamp-start: "<!ENTITY TIMESTAMP [\"']" -->
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<!-- time-stamp-end: "[\"']>" -->