46
48
<refname><command>&COMMANDNAME;</command></refname>
50
Client for <application>Mandos</application>
54
56
<command>&COMMANDNAME;</command>
56
58
<arg choice="plain"><option>--connect
57
<replaceable>IPADDR</replaceable><literal>:</literal
59
<replaceable>ADDRESS</replaceable><literal>:</literal
58
60
><replaceable>PORT</replaceable></option></arg>
59
61
<arg choice="plain"><option>-c
60
<replaceable>IPADDR</replaceable><literal>:</literal
62
<replaceable>ADDRESS</replaceable><literal>:</literal
61
63
><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>
72
67
<arg choice="plain"><option>--interface
73
68
<replaceable>NAME</replaceable></option></arg>
74
69
<arg choice="plain"><option>-i
122
121
</refsynopsisdiv>
124
123
<refsect1 id="description">
125
124
<title>DESCRIPTION</title>
127
126
<command>&COMMANDNAME;</command> is a client program that
128
127
communicates with <citerefentry><refentrytitle
129
128
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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.
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
137
141
This program is not meant to be run directly; it is really meant
138
142
to run as a plugin of the <application>Mandos</application>
139
143
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
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.
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.
202
188
assumed to separate the address from the port number.
205
This option is normally only useful for debugging.
191
This option is normally only useful for testing and
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>
198
<term><option>--interface=<replaceable
199
>NAME</replaceable></option></term>
230
201
<replaceable>NAME</replaceable></option></term>
233
204
Network interface that will be brought up and scanned for
234
Mandos servers to connect to. The default it
235
<quote><literal>eth0</literal></quote>.
205
Mandos servers to connect to. The default is the empty
206
string, which will automatically choose an appropriate
210
If the <option>--connect</option> option is used, this
211
specifies the interface to use to connect to the address
215
Note that since this program will normally run in the
216
initial RAM disk environment, the interface must be an
217
interface which exists at that stage. Thus, the interface
218
can not be a pseudo-interface such as <quote>br0</quote>
219
or <quote>tun0</quote>; such interfaces will not exist
220
until much later in the boot process, and can not be used
224
<replaceable>NAME</replaceable> can be the string
225
<quote><literal>none</literal></quote>; this will not use
226
any specific interface, and will not bring up an interface
227
on startup. This is not recommended, and only meant for
344
<refsect1 id="overview">
345
<title>OVERVIEW</title>
346
<xi:include href="../overview.xml"/>
348
This program is the client part. It is a plugin started by
349
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
350
<manvolnum>8mandos</manvolnum></citerefentry> which will run in
351
an initial <acronym>RAM</acronym> disk environment.
354
This program could, theoretically, be used as a keyscript in
355
<filename>/etc/crypttab</filename>, but it would then be
356
impossible to enter a password for the encrypted root disk at
357
the console, since this program does not read from the console
358
at all. This is why a separate plugin runner (<citerefentry>
359
<refentrytitle>plugin-runner</refentrytitle>
360
<manvolnum>8mandos</manvolnum></citerefentry>) is used to run
361
both this program and others in in parallel,
362
<emphasis>one</emphasis> of which will prompt for passwords on
336
367
<refsect1 id="exit_status">
337
368
<title>EXIT STATUS</title>
341
372
successfully decrypted and output on standard output. The
342
373
program will exit with a non-zero exit status only if a critical
343
374
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> -->
375
<application>Mandos</application> servers as they appear, trying
376
to get a decryptable password and print it.
380
<refsect1 id="environment">
381
<title>ENVIRONMENT</title>
383
This program does not use any environment variables, not even
384
the ones provided by <citerefentry><refentrytitle
385
>cryptsetup</refentrytitle><manvolnum>8</manvolnum>
390
<refsect1 id="files">
394
<term><filename>/conf/conf.d/mandos/pubkey.txt</filename
396
<term><filename>/conf/conf.d/mandos/seckey.txt</filename
400
OpenPGP public and private key files, in <quote>ASCII
401
Armor</quote> format. These are the default file names,
402
they can be changed with the <option>--pubkey</option> and
403
<option>--seckey</option> options.
410
<!-- <refsect1 id="bugs"> -->
411
<!-- <title>BUGS</title> -->
352
<!-- This program does not use any environment variables. -->
354
414
<!-- </refsect1> -->
368
416
<refsect1 id="example">
369
417
<title>EXAMPLE</title>
419
Note that normally, command line options will not be given
420
directly, but via options for the Mandos <citerefentry
421
><refentrytitle>plugin-runner</refentrytitle>
422
<manvolnum>8mandos</manvolnum></citerefentry>.
426
Normal invocation needs no options, if the network interface
427
is <quote>eth0</quote>:
430
<userinput>&COMMANDNAME;</userinput>
435
Search for Mandos servers (and connect to them) using another
439
<!-- do not wrap this line -->
440
<userinput>&COMMANDNAME; --interface eth1</userinput>
445
Run in debug mode, and use a custom key:
449
<!-- do not wrap this line -->
450
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt</userinput>
456
Run in debug mode, with a custom key, and do not use Zeroconf
457
to locate a server; connect directly to the IPv6 link-local
458
address <quote><systemitem class="ipaddress"
459
>fe80::aede:48ff:fe71:f6f2</systemitem></quote>, port 4711,
460
using interface eth2:
464
<!-- do not wrap this line -->
465
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt --connect fe80::aede:48ff:fe71:f6f2:4711 --interface eth2</userinput>
374
471
<refsect1 id="security">
375
472
<title>SECURITY</title>
474
This program is set-uid to root, but will switch back to the
475
original (and presumably non-privileged) user and group after
476
bringing up the network interface.
479
To use this program for its intended purpose (see <xref
480
linkend="purpose"/>), the password for the root file system will
481
have to be given out to be stored in a server computer, after
482
having been encrypted using an OpenPGP key. This encrypted data
483
which will be stored in a server can only be decrypted by the
484
OpenPGP key, and the data will only be given out to those
485
clients who can prove they actually have that key. This key,
486
however, is stored unencrypted on the client side in its initial
487
<acronym>RAM</acronym> disk image file system. This is normally
488
readable by all, but this is normally fixed during installation
489
of this program; file permissions are set so that no-one is able
493
The only remaining weak point is that someone with physical
494
access to the client hard drive might turn off the client
495
computer, read the OpenPGP keys directly from the hard drive,
496
and communicate with the server. To safeguard against this, the
497
server is supposed to notice the client disappearing and stop
498
giving out the encrypted data. Therefore, it is important to
499
set the timeout and checker interval values tightly on the
500
server. See <citerefentry><refentrytitle
501
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
504
It will also help if the checker program on the server is
505
configured to request something from the client which can not be
506
spoofed by someone else on the network, unlike unencrypted
507
<acronym>ICMP</acronym> echo (<quote>ping</quote>) replies.
510
<emphasis>Note</emphasis>: This makes it completely insecure to
511
have <application >Mandos</application> clients which dual-boot
512
to another operating system which is <emphasis>not</emphasis>
513
trusted to keep the initial <acronym>RAM</acronym> disk image
380
518
<refsect1 id="see_also">
381
519
<title>SEE ALSO</title>
521
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
522
<manvolnum>8</manvolnum></citerefentry>,
523
<citerefentry><refentrytitle>crypttab</refentrytitle>
524
<manvolnum>5</manvolnum></citerefentry>,
383
525
<citerefentry><refentrytitle>mandos</refentrytitle>
384
526
<manvolnum>8</manvolnum></citerefentry>,
385
527
<citerefentry><refentrytitle>password-prompt</refentrytitle>
387
529
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
388
530
<manvolnum>8mandos</manvolnum></citerefentry>
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>
535
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
539
Zeroconf is the network protocol standard used for finding
540
Mandos servers on the local network.
546
<ulink url="http://www.avahi.org/">Avahi</ulink>
550
Avahi is the library this program calls to find Zeroconf
557
<ulink url="http://www.gnu.org/software/gnutls/"
562
GnuTLS is the library this client uses to implement TLS for
563
communicating securely with the server, and at the same time
564
send the public OpenPGP key to the server.
570
<ulink url="http://www.gnupg.org/related_software/gpgme/"
575
GPGME is the library used to decrypt the OpenPGP data sent
582
RFC 4291: <citetitle>IP Version 6 Addressing
583
Architecture</citetitle>
588
<term>Section 2.2: <citetitle>Text Representation of
589
Addresses</citetitle></term>
590
<listitem><para/></listitem>
593
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
594
Address</citetitle></term>
595
<listitem><para/></listitem>
598
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
599
Addresses</citetitle></term>
602
This client uses IPv6 link-local addresses, which are
603
immediately usable since a link-local addresses is
604
automatically assigned to a network interfaces when it
614
RFC 4346: <citetitle>The Transport Layer Security (TLS)
615
Protocol Version 1.1</citetitle>
619
TLS 1.1 is the protocol implemented by GnuTLS.
625
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
629
The data received from the server is binary encrypted
636
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
641
This is implemented by GnuTLS and used by this program so
642
that OpenPGP keys can be used.
429
650
<!-- Local Variables: -->
430
651
<!-- time-stamp-start: "<!ENTITY TIMESTAMP [\"']" -->
431
652
<!-- time-stamp-end: "[\"']>" -->