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46
<refname><command>&COMMANDNAME;</command></refname>
51
Client for <application>Mandos</application>
57
54
<command>&COMMANDNAME;</command>
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<arg choice="plain"><option>--connect
60
<replaceable>ADDRESS</replaceable><literal>:</literal
57
<replaceable>IPADDR</replaceable><literal>:</literal
61
58
><replaceable>PORT</replaceable></option></arg>
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<arg choice="plain"><option>-c
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<replaceable>ADDRESS</replaceable><literal>:</literal
60
<replaceable>IPADDR</replaceable><literal>:</literal
64
61
><replaceable>PORT</replaceable></option></arg>
65
<arg choice="plain"><option>--keydir
66
<replaceable>DIRECTORY</replaceable></option></arg>
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<arg choice="plain"><option>-d
68
<replaceable>DIRECTORY</replaceable></option></arg>
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<arg choice="plain"><option>--interface
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73
<replaceable>NAME</replaceable></option></arg>
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<arg choice="plain"><option>-i
126
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</refsynopsisdiv>
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<refsect1 id="description">
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<title>DESCRIPTION</title>
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127
<command>&COMMANDNAME;</command> is a client program that
132
128
communicates with <citerefentry><refentrytitle
133
129
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>
134
to get a password. In slightly more detail, this client program
135
brings up a network interface, uses the interface’s IPv6
136
link-local address to get network connectivity, uses Zeroconf to
137
find servers on the local network, and communicates with servers
138
using TLS with an OpenPGP key to ensure authenticity and
139
confidentiality. This client program keeps running, trying all
140
servers on the network, until it receives a satisfactory reply
141
or a TERM signal. After all servers have been tried, all
142
servers are periodically retried. If no servers are found it
143
will wait indefinitely for new servers to appear.
130
to get a password. It uses IPv6 link-local addresses to get
131
network connectivity, Zeroconf to find the server, and TLS with
132
an OpenPGP key to ensure authenticity and confidentiality. It
133
keeps running, trying all servers on the network, until it
134
receives a satisfactory reply.
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137
This program is not meant to be run directly; it is really meant
147
138
to run as a plugin of the <application>Mandos</application>
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139
<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>
153
</citerefentry> file.
140
<manvolnum>8mandos</manvolnum></citerefentry>, which in turn
141
runs as a <quote>keyscript</quote> specified in the
142
<citerefentry><refentrytitle>crypttab</refentrytitle>
143
<manvolnum>5</manvolnum></citerefentry> file.
193
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assumed to separate the address from the port number.
196
This option is normally only useful for testing and
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This option is normally only useful for debugging.
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<term><option>--interface=<replaceable
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>NAME</replaceable></option></term>
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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 to read the OpenPGP key files
218
<filename>pubkey.txt</filename> and
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<filename>seckey.txt</filename> from. The default is
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<filename>/conf/conf.d/mandos</filename> (in the initial
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<acronym>RAM</acronym> disk environment).
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<term><option>--interface=
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<replaceable>NAME</replaceable></option></term>
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<replaceable>NAME</replaceable></option></term>
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Network interface that will be brought up and scanned for
210
Mandos servers to connect to. The default is the empty
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string, which will automatically choose an appropriate
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If the <option>--connect</option> option is used, this
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specifies the interface to use to connect to the address
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Note that since this program will normally run in the
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initial RAM disk environment, the interface must be an
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interface which exists at that stage. Thus, the interface
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can not be a pseudo-interface such as <quote>br0</quote>
224
or <quote>tun0</quote>; such interfaces will not exist
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until much later in the boot process, and can not be used
229
<replaceable>NAME</replaceable> can be the string
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<quote><literal>none</literal></quote>; this will not use
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any specific interface, and will not bring up an interface
232
on startup. This is not recommended, and only meant for
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Mandos servers to connect to. The default it
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<quote><literal>eth0</literal></quote>.
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<term><option>--delay=<replaceable
288
>SECONDS</replaceable></option></term>
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After bringing the network interface up, the program waits
292
for the interface to arrive in a <quote>running</quote>
293
state before proceeding. During this time, the kernel log
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level will be lowered to reduce clutter on the system
295
console, alleviating any other plugins which might be
296
using the system console. This option sets the upper
297
limit of seconds to wait. The default is 2.5 seconds.
303
<term><option>--retry=<replaceable
304
>SECONDS</replaceable></option></term>
307
All Mandos servers are tried repeatedly until a password
308
is received. This value specifies, in seconds, how long
309
between each successive try <emphasis>for the same
310
server</emphasis>. The default is 10 seconds.
316
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<term><option>--debug</option></term>
362
<refsect1 id="overview">
363
<title>OVERVIEW</title>
364
<xi:include href="../overview.xml"/>
366
This program is the client part. It is a plugin started by
367
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
368
<manvolnum>8mandos</manvolnum></citerefentry> which will run in
369
an initial <acronym>RAM</acronym> disk environment.
372
This program could, theoretically, be used as a keyscript in
373
<filename>/etc/crypttab</filename>, but it would then be
374
impossible to enter a password for the encrypted root disk at
375
the console, since this program does not read from the console
376
at all. This is why a separate plugin runner (<citerefentry>
377
<refentrytitle>plugin-runner</refentrytitle>
378
<manvolnum>8mandos</manvolnum></citerefentry>) is used to run
379
both this program and others in in parallel,
380
<emphasis>one</emphasis> of which will prompt for passwords on
385
336
<refsect1 id="exit_status">
386
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<title>EXIT STATUS</title>
389
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server could be found and the password received from it could be
390
341
successfully decrypted and output on standard output. The
391
342
program will exit with a non-zero exit status only if a critical
392
error occurs. Otherwise, it will forever connect to any
393
discovered <application>Mandos</application> servers, trying to
394
get a decryptable password and print it.
398
<refsect1 id="environment">
399
<title>ENVIRONMENT</title>
401
This program does not use any environment variables, not even
402
the ones provided by <citerefentry><refentrytitle
403
>cryptsetup</refentrytitle><manvolnum>8</manvolnum>
408
<refsect1 id="files">
412
<term><filename>/conf/conf.d/mandos/pubkey.txt</filename
414
<term><filename>/conf/conf.d/mandos/seckey.txt</filename
418
OpenPGP public and private key files, in <quote>ASCII
419
Armor</quote> format. These are the default file names,
420
they can be changed with the <option>--pubkey</option> and
421
<option>--seckey</option> options.
428
<!-- <refsect1 id="bugs"> -->
429
<!-- <title>BUGS</title> -->
343
error occurs. Otherwise, it will forever connect to new
344
<application>Mandosservers</application> servers as they appear,
345
trying to get a decryptable password.
349
<!-- <refsect1 id="environment"> -->
350
<!-- <title>ENVIRONMENT</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>
437
Note that normally, command line options will not be given
438
directly, but via options for the Mandos <citerefentry
439
><refentrytitle>plugin-runner</refentrytitle>
440
<manvolnum>8mandos</manvolnum></citerefentry>.
444
Normal invocation needs no options, if the network interface
445
is <quote>eth0</quote>:
448
<userinput>&COMMANDNAME;</userinput>
453
Search for Mandos servers (and connect to them) using another
457
<!-- do not wrap this line -->
458
<userinput>&COMMANDNAME; --interface eth1</userinput>
463
Run in debug mode, and use a custom key:
467
<!-- do not wrap this line -->
468
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt</userinput>
474
Run in debug mode, with a custom key, and do not use Zeroconf
475
to locate a server; connect directly to the IPv6 link-local
476
address <quote><systemitem class="ipaddress"
477
>fe80::aede:48ff:fe71:f6f2</systemitem></quote>, port 4711,
478
using interface eth2:
482
<!-- do not wrap this line -->
483
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt --connect fe80::aede:48ff:fe71:f6f2:4711 --interface eth2</userinput>
489
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<refsect1 id="security">
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375
<title>SECURITY</title>
492
This program is set-uid to root, but will switch back to the
493
original (and presumably non-privileged) user and group after
494
bringing up the network interface.
497
To use this program for its intended purpose (see <xref
498
linkend="purpose"/>), the password for the root file system will
499
have to be given out to be stored in a server computer, after
500
having been encrypted using an OpenPGP key. This encrypted data
501
which will be stored in a server can only be decrypted by the
502
OpenPGP key, and the data will only be given out to those
503
clients who can prove they actually have that key. This key,
504
however, is stored unencrypted on the client side in its initial
505
<acronym>RAM</acronym> disk image file system. This is normally
506
readable by all, but this is normally fixed during installation
507
of this program; file permissions are set so that no-one is able
511
The only remaining weak point is that someone with physical
512
access to the client hard drive might turn off the client
513
computer, read the OpenPGP keys directly from the hard drive,
514
and communicate with the server. To safeguard against this, the
515
server is supposed to notice the client disappearing and stop
516
giving out the encrypted data. Therefore, it is important to
517
set the timeout and checker interval values tightly on the
518
server. See <citerefentry><refentrytitle
519
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
522
It will also help if the checker program on the server is
523
configured to request something from the client which can not be
524
spoofed by someone else on the network, unlike unencrypted
525
<acronym>ICMP</acronym> echo (<quote>ping</quote>) replies.
528
<emphasis>Note</emphasis>: This makes it completely insecure to
529
have <application >Mandos</application> clients which dual-boot
530
to another operating system which is <emphasis>not</emphasis>
531
trusted to keep the initial <acronym>RAM</acronym> disk image
536
380
<refsect1 id="see_also">
537
381
<title>SEE ALSO</title>
539
<citerefentry><refentrytitle>intro</refentrytitle>
540
<manvolnum>8mandos</manvolnum></citerefentry>,
541
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
542
<manvolnum>8</manvolnum></citerefentry>,
543
<citerefentry><refentrytitle>crypttab</refentrytitle>
544
<manvolnum>5</manvolnum></citerefentry>,
545
383
<citerefentry><refentrytitle>mandos</refentrytitle>
546
384
<manvolnum>8</manvolnum></citerefentry>,
547
385
<citerefentry><refentrytitle>password-prompt</refentrytitle>
549
387
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
550
388
<manvolnum>8mandos</manvolnum></citerefentry>
555
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
559
Zeroconf is the network protocol standard used for finding
560
Mandos servers on the local network.
566
<ulink url="http://www.avahi.org/">Avahi</ulink>
570
Avahi is the library this program calls to find Zeroconf
577
<ulink url="http://www.gnu.org/software/gnutls/"
582
GnuTLS is the library this client uses to implement TLS for
583
communicating securely with the server, and at the same time
584
send the public OpenPGP key to the server.
590
<ulink url="http://www.gnupg.org/related_software/gpgme/"
595
GPGME is the library used to decrypt the OpenPGP data sent
602
RFC 4291: <citetitle>IP Version 6 Addressing
603
Architecture</citetitle>
608
<term>Section 2.2: <citetitle>Text Representation of
609
Addresses</citetitle></term>
610
<listitem><para/></listitem>
613
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
614
Address</citetitle></term>
615
<listitem><para/></listitem>
618
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
619
Addresses</citetitle></term>
622
This client uses IPv6 link-local addresses, which are
623
immediately usable since a link-local addresses is
624
automatically assigned to a network interfaces when it
634
RFC 4346: <citetitle>The Transport Layer Security (TLS)
635
Protocol Version 1.1</citetitle>
639
TLS 1.1 is the protocol implemented by GnuTLS.
645
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
649
The data received from the server is binary encrypted
656
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
661
This is implemented by GnuTLS and used by this program so
662
that OpenPGP keys can be used.
392
<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/">
411
<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>
421
<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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