48
46
<refname><command>&COMMANDNAME;</command></refname>
50
Client for <application>Mandos</application>
56
54
<command>&COMMANDNAME;</command>
58
56
<arg choice="plain"><option>--connect
59
<replaceable>ADDRESS</replaceable><literal>:</literal
57
<replaceable>IPADDR</replaceable><literal>:</literal
60
58
><replaceable>PORT</replaceable></option></arg>
61
59
<arg choice="plain"><option>-c
62
<replaceable>ADDRESS</replaceable><literal>:</literal
60
<replaceable>IPADDR</replaceable><literal>:</literal
63
61
><replaceable>PORT</replaceable></option></arg>
65
<arg choice="plain"><option>--keydir
66
<replaceable>DIRECTORY</replaceable></option></arg>
67
<arg choice="plain"><option>-d
68
<replaceable>DIRECTORY</replaceable></option></arg>
67
72
<arg choice="plain"><option>--interface
68
73
<replaceable>NAME</replaceable></option></arg>
69
74
<arg choice="plain"><option>-i
121
122
</refsynopsisdiv>
123
124
<refsect1 id="description">
124
125
<title>DESCRIPTION</title>
126
127
<command>&COMMANDNAME;</command> is a client program that
127
128
communicates with <citerefentry><refentrytitle
128
129
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>
129
to get a password. In slightly more detail, this client program
130
brings up a network interface, uses the interface’s IPv6
131
link-local address to get network connectivity, uses Zeroconf to
132
find servers on the local network, and communicates with servers
133
using TLS with an OpenPGP key to ensure authenticity and
134
confidentiality. This client program keeps running, trying all
135
servers on the network, until it receives a satisfactory reply
136
or a TERM signal is received. If no servers are found, or after
137
all servers have been tried, it waits indefinitely for new
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.
141
137
This program is not meant to be run directly; it is really meant
142
138
to run as a plugin of the <application>Mandos</application>
143
139
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
144
<manvolnum>8mandos</manvolnum></citerefentry>, which runs in the
145
initial <acronym>RAM</acronym> disk environment because it is
146
specified as a <quote>keyscript</quote> in the <citerefentry>
147
<refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
148
</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.
188
202
assumed to separate the address from the port number.
191
This option is normally only useful for testing and
205
This option is normally only useful for debugging.
198
<term><option>--interface=<replaceable
199
>NAME</replaceable></option></term>
211
<term><option>--keydir=<replaceable
212
>DIRECTORY</replaceable></option></term>
214
<replaceable>DIRECTORY</replaceable></option></term>
217
Directory to read the OpenPGP key files
218
<filename>pubkey.txt</filename> and
219
<filename>seckey.txt</filename> from. The default is
220
<filename>/conf/conf.d/mandos</filename> (in the initial
221
<acronym>RAM</acronym> disk environment).
227
<term><option>--interface=
228
<replaceable>NAME</replaceable></option></term>
201
230
<replaceable>NAME</replaceable></option></term>
204
233
Network interface that will be brought up and scanned for
205
Mandos servers to connect to. The default is
234
Mandos servers to connect to. The default it
206
235
<quote><literal>eth0</literal></quote>.
209
If the <option>--connect</option> option is used, this
210
specifies the interface to use to connect to the address
214
Note that since this program will normally run in the
215
initial RAM disk environment, the interface must be an
216
interface which exists at that stage. Thus, the interface
217
can not be a pseudo-interface such as <quote>br0</quote>
218
or <quote>tun0</quote>; such interfaces will not exist
219
until much later in the boot process, and can not be used
223
<replaceable>NAME</replaceable> can be the empty string;
224
this will not use any specific interface, and will not
225
bring up an interface on startup. This is not
226
recommended, and only meant for advanced users.
342
<refsect1 id="overview">
343
<title>OVERVIEW</title>
344
<xi:include href="../overview.xml"/>
346
This program is the client part. It is a plugin started by
347
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
348
<manvolnum>8mandos</manvolnum></citerefentry> which will run in
349
an initial <acronym>RAM</acronym> disk environment.
352
This program could, theoretically, be used as a keyscript in
353
<filename>/etc/crypttab</filename>, but it would then be
354
impossible to enter a password for the encrypted root disk at
355
the console, since this program does not read from the console
356
at all. This is why a separate plugin runner (<citerefentry>
357
<refentrytitle>plugin-runner</refentrytitle>
358
<manvolnum>8mandos</manvolnum></citerefentry>) is used to run
359
both this program and others in in parallel,
360
<emphasis>one</emphasis> of which will prompt for passwords on
365
336
<refsect1 id="exit_status">
366
337
<title>EXIT STATUS</title>
370
341
successfully decrypted and output on standard output. The
371
342
program will exit with a non-zero exit status only if a critical
372
343
error occurs. Otherwise, it will forever connect to new
373
<application>Mandos</application> servers as they appear, trying
374
to get a decryptable password and print it.
378
<refsect1 id="environment">
379
<title>ENVIRONMENT</title>
381
This program does not use any environment variables, not even
382
the ones provided by <citerefentry><refentrytitle
383
>cryptsetup</refentrytitle><manvolnum>8</manvolnum>
388
<refsect1 id="files">
392
<term><filename>/conf/conf.d/mandos/pubkey.txt</filename
394
<term><filename>/conf/conf.d/mandos/seckey.txt</filename
398
OpenPGP public and private key files, in <quote>ASCII
399
Armor</quote> format. These are the default file names,
400
they can be changed with the <option>--pubkey</option> and
401
<option>--seckey</option> options.
408
<!-- <refsect1 id="bugs"> -->
409
<!-- <title>BUGS</title> -->
344
<application>Mandosservers</application> servers as they appear,
345
trying to get a decryptable password.
349
<!-- <refsect1 id="environment"> -->
350
<!-- <title>ENVIRONMENT</title> -->
352
<!-- This program does not use any environment variables. -->
412
354
<!-- </refsect1> -->
414
368
<refsect1 id="example">
415
369
<title>EXAMPLE</title>
417
Note that normally, command line options will not be given
418
directly, but via options for the Mandos <citerefentry
419
><refentrytitle>plugin-runner</refentrytitle>
420
<manvolnum>8mandos</manvolnum></citerefentry>.
424
Normal invocation needs no options, if the network interface
425
is <quote>eth0</quote>:
428
<userinput>&COMMANDNAME;</userinput>
433
Search for Mandos servers (and connect to them) using another
437
<!-- do not wrap this line -->
438
<userinput>&COMMANDNAME; --interface eth1</userinput>
443
Run in debug mode, and use a custom key:
447
<!-- do not wrap this line -->
448
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt</userinput>
454
Run in debug mode, with a custom key, and do not use Zeroconf
455
to locate a server; connect directly to the IPv6 link-local
456
address <quote><systemitem class="ipaddress"
457
>fe80::aede:48ff:fe71:f6f2</systemitem></quote>, port 4711,
458
using interface eth2:
462
<!-- do not wrap this line -->
463
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt --connect fe80::aede:48ff:fe71:f6f2:4711 --interface eth2</userinput>
469
374
<refsect1 id="security">
470
375
<title>SECURITY</title>
472
This program is set-uid to root, but will switch back to the
473
original (and presumably non-privileged) user and group after
474
bringing up the network interface.
477
To use this program for its intended purpose (see <xref
478
linkend="purpose"/>), the password for the root file system will
479
have to be given out to be stored in a server computer, after
480
having been encrypted using an OpenPGP key. This encrypted data
481
which will be stored in a server can only be decrypted by the
482
OpenPGP key, and the data will only be given out to those
483
clients who can prove they actually have that key. This key,
484
however, is stored unencrypted on the client side in its initial
485
<acronym>RAM</acronym> disk image file system. This is normally
486
readable by all, but this is normally fixed during installation
487
of this program; file permissions are set so that no-one is able
491
The only remaining weak point is that someone with physical
492
access to the client hard drive might turn off the client
493
computer, read the OpenPGP keys directly from the hard drive,
494
and communicate with the server. To safeguard against this, the
495
server is supposed to notice the client disappearing and stop
496
giving out the encrypted data. Therefore, it is important to
497
set the timeout and checker interval values tightly on the
498
server. See <citerefentry><refentrytitle
499
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
502
It will also help if the checker program on the server is
503
configured to request something from the client which can not be
504
spoofed by someone else on the network, unlike unencrypted
505
<acronym>ICMP</acronym> echo (<quote>ping</quote>) replies.
508
<emphasis>Note</emphasis>: This makes it completely insecure to
509
have <application >Mandos</application> clients which dual-boot
510
to another operating system which is <emphasis>not</emphasis>
511
trusted to keep the initial <acronym>RAM</acronym> disk image
516
380
<refsect1 id="see_also">
517
381
<title>SEE ALSO</title>
519
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
520
<manvolnum>8</manvolnum></citerefentry>,
521
<citerefentry><refentrytitle>crypttab</refentrytitle>
522
<manvolnum>5</manvolnum></citerefentry>,
523
383
<citerefentry><refentrytitle>mandos</refentrytitle>
524
384
<manvolnum>8</manvolnum></citerefentry>,
525
385
<citerefentry><refentrytitle>password-prompt</refentrytitle>
527
387
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
528
388
<manvolnum>8mandos</manvolnum></citerefentry>
533
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
537
Zeroconf is the network protocol standard used for finding
538
Mandos servers on the local network.
544
<ulink url="http://www.avahi.org/">Avahi</ulink>
548
Avahi is the library this program calls to find Zeroconf
555
<ulink url="http://www.gnu.org/software/gnutls/"
560
GnuTLS is the library this client uses to implement TLS for
561
communicating securely with the server, and at the same time
562
send the public OpenPGP key to the server.
568
<ulink url="http://www.gnupg.org/related_software/gpgme/"
573
GPGME is the library used to decrypt the OpenPGP data sent
580
RFC 4291: <citetitle>IP Version 6 Addressing
581
Architecture</citetitle>
586
<term>Section 2.2: <citetitle>Text Representation of
587
Addresses</citetitle></term>
588
<listitem><para/></listitem>
591
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
592
Address</citetitle></term>
593
<listitem><para/></listitem>
596
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
597
Addresses</citetitle></term>
600
This client uses IPv6 link-local addresses, which are
601
immediately usable since a link-local addresses is
602
automatically assigned to a network interfaces when it
612
RFC 4346: <citetitle>The Transport Layer Security (TLS)
613
Protocol Version 1.1</citetitle>
617
TLS 1.1 is the protocol implemented by GnuTLS.
623
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
627
The data received from the server is binary encrypted
634
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
639
This is implemented by GnuTLS and used by this program so
640
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>
648
429
<!-- Local Variables: -->
649
430
<!-- time-stamp-start: "<!ENTITY TIMESTAMP [\"']" -->
650
431
<!-- time-stamp-end: "[\"']>" -->