131
122
</refsynopsisdiv>
133
124
<refsect1 id="description">
134
125
<title>DESCRIPTION</title>
136
127
<command>&COMMANDNAME;</command> is a client program that
137
128
communicates with <citerefentry><refentrytitle
138
129
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>
139
to get a password. In slightly more detail, this client program
140
brings up a network interface, uses the interface’s IPv6
141
link-local address to get network connectivity, uses Zeroconf to
142
find servers on the local network, and communicates with servers
143
using TLS with an OpenPGP key to ensure authenticity and
144
confidentiality. This client program keeps running, trying all
145
servers on the network, until it receives a satisfactory reply
146
or a TERM signal. After all servers have been tried, all
147
servers are periodically retried. If no servers are found it
148
will wait indefinitely for new servers to appear.
151
The network interface is selected like this: If an interface is
152
specified using the <option>--interface</option> option, that
153
interface is used. Otherwise, <command>&COMMANDNAME;</command>
154
will choose any interface that is up and running and is not a
155
loopback interface, is not a point-to-point interface, is
156
capable of broadcasting and does not have the NOARP flag (see
157
<citerefentry><refentrytitle>netdevice</refentrytitle>
158
<manvolnum>7</manvolnum></citerefentry>). (If the
159
<option>--connect</option> option is used, point-to-point
160
interfaces and non-broadcast interfaces are accepted.) If no
161
acceptable interfaces are found, re-run the check but without
162
the <quote>up and running</quote> requirement, and manually take
163
the selected interface up (and later take it down on program
167
Before a network interface is selected, all <quote>network
168
hooks</quote> are run; see <xref linkend="network-hooks"/>.
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.
171
137
This program is not meant to be run directly; it is really meant
228
<term><option>--interface=<replaceable
229
>NAME</replaceable></option></term>
194
<term><option>--keydir=<replaceable
195
>DIRECTORY</replaceable></option></term>
197
<replaceable>DIRECTORY</replaceable></option></term>
200
Directory to read the OpenPGP key files
201
<filename>pubkey.txt</filename> and
202
<filename>seckey.txt</filename> from. The default is
203
<filename>/conf/conf.d/mandos</filename> (in the initial
204
<acronym>RAM</acronym> disk environment).
210
<term><option>--interface=
211
<replaceable>NAME</replaceable></option></term>
231
213
<replaceable>NAME</replaceable></option></term>
234
216
Network interface that will be brought up and scanned for
235
Mandos servers to connect to. The default is the empty
236
string, which will automatically choose an appropriate
240
If the <option>--connect</option> option is used, this
241
specifies the interface to use to connect to the address
245
Note that since this program will normally run in the
246
initial RAM disk environment, the interface must be an
247
interface which exists at that stage. Thus, the interface
248
can not be a pseudo-interface such as <quote>br0</quote>
249
or <quote>tun0</quote>; such interfaces will not exist
250
until much later in the boot process, and can not be used
251
by this program, unless created by a <quote>network
252
hook</quote> — see <xref linkend="network-hooks"/>.
255
<replaceable>NAME</replaceable> can be the string
256
<quote><literal>none</literal></quote>; this will not use
257
any specific interface, and will not bring up an interface
258
on startup. This is not recommended, and only meant for
217
Mandos servers to connect to. The default it
218
<quote><literal>eth0</literal></quote>.
448
<refsect1 id="network-hooks">
449
<title>NETWORK HOOKS</title>
451
If a network interface like a bridge or tunnel is required to
452
find a Mandos server, this requires the interface to be up and
453
running before <command>&COMMANDNAME;</command> starts looking
454
for Mandos servers. This can be accomplished by creating a
455
<quote>network hook</quote> program, and placing it in a special
459
Before the network is used (and again before program exit), any
460
runnable programs found in the network hook directory are run
461
with the argument <quote><literal>start</literal></quote> or
462
<quote><literal>stop</literal></quote>. This should bring up or
463
down, respectively, any network interface which
464
<command>&COMMANDNAME;</command> should use.
466
<refsect2 id="hook-requirements">
467
<title>REQUIREMENTS</title>
469
A network hook must be an executable file, and its name must
470
consist entirely of upper and lower case letters, digits,
471
underscores, and hyphens.
474
A network hook will receive one argument, which can be one of
479
<term><literal>start</literal></term>
482
This should make the network hook create (if necessary)
483
and bring up a network interface.
488
<term><literal>stop</literal></term>
491
This should make the network hook take down a network
492
interface, and delete it if it did not exist previously.
497
<term><literal>files</literal></term>
500
This should make the network hook print, <emphasis>on
501
separate lines</emphasis>, all the files needed for it
502
to run. (These files will be copied into the initial
503
RAM filesystem.) Intended use is for a network hook
504
which is a shell script to print its needed binaries.
507
It is not necessary to print any non-executable files
508
already in the network hook directory, these will be
509
copied implicitly if they otherwise satisfy the name
516
The network hook will be provided with a number of environment
521
<term><envar>MANDOSNETHOOKDIR</envar></term>
524
The network hook directory, specified to
525
<command>&COMMANDNAME;</command> by the
526
<option>--network-hook-dir</option> option. Note: this
527
should <emphasis>always</emphasis> be used by the
528
network hook to refer to itself or any files it may
534
<term><envar>DEVICE</envar></term>
537
The network interface, as specified to
538
<command>&COMMANDNAME;</command> by the
539
<option>--interface</option> option. If this is not the
540
interface a hook will bring up, there is no reason for a
546
<term><envar>MODE</envar></term>
549
This will be the same as the first argument;
550
i.e. <quote><literal>start</literal></quote>,
551
<quote><literal>stop</literal></quote>, or
552
<quote><literal>files</literal></quote>.
557
<term><envar>VERBOSITY</envar></term>
560
This will be the <quote><literal>1</literal></quote> if
561
the <option>--debug</option> option is passed to
562
<command>&COMMANDNAME;</command>, otherwise
563
<quote><literal>0</literal></quote>.
568
<term><envar>DELAY</envar></term>
571
This will be the same as the <option>--delay</option>
572
option passed to <command>&COMMANDNAME;</command>.
578
A hook may not read from standard input, and should be
579
restrictive in printing to standard output or standard error
580
unless <varname>VERBOSITY</varname> is
581
<quote><literal>1</literal></quote>.
586
<refsect1 id="files">
587
363
<title>FILES</title>
590
<term><filename>/conf/conf.d/mandos/pubkey.txt</filename
592
<term><filename>/conf/conf.d/mandos/seckey.txt</filename
596
OpenPGP public and private key files, in <quote>ASCII
597
Armor</quote> format. These are the default file names,
598
they can be changed with the <option>--pubkey</option> and
599
<option>--seckey</option> options.
605
class="directory">/lib/mandos/network-hooks.d</filename></term>
608
Directory where network hooks are located. Change this
609
with the <option>--network-hook-dir</option> option. See
610
<xref linkend="network-hooks"/>.
617
<!-- <refsect1 id="bugs"> -->
618
<!-- <title>BUGS</title> -->
623
374
<refsect1 id="example">
624
375
<title>EXAMPLE</title>
626
Note that normally, command line options will not be given
627
directly, but via options for the Mandos <citerefentry
628
><refentrytitle>plugin-runner</refentrytitle>
629
<manvolnum>8mandos</manvolnum></citerefentry>.
633
Normal invocation needs no options, if the network interface
634
is <quote>eth0</quote>:
637
<userinput>&COMMANDNAME;</userinput>
642
Search for Mandos servers (and connect to them) using another
646
<!-- do not wrap this line -->
647
<userinput>&COMMANDNAME; --interface eth1</userinput>
652
Run in debug mode, and use a custom key:
656
<!-- do not wrap this line -->
657
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt</userinput>
663
Run in debug mode, with a custom key, and do not use Zeroconf
664
to locate a server; connect directly to the IPv6 link-local
665
address <quote><systemitem class="ipaddress"
666
>fe80::aede:48ff:fe71:f6f2</systemitem></quote>, port 4711,
667
using interface eth2:
671
<!-- do not wrap this line -->
672
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt --connect fe80::aede:48ff:fe71:f6f2:4711 --interface eth2</userinput>
678
380
<refsect1 id="security">
679
381
<title>SECURITY</title>
681
This program is set-uid to root, but will switch back to the
682
original (and presumably non-privileged) user and group after
683
bringing up the network interface.
686
To use this program for its intended purpose (see <xref
687
linkend="purpose"/>), the password for the root file system will
688
have to be given out to be stored in a server computer, after
689
having been encrypted using an OpenPGP key. This encrypted data
690
which will be stored in a server can only be decrypted by the
691
OpenPGP key, and the data will only be given out to those
692
clients who can prove they actually have that key. This key,
693
however, is stored unencrypted on the client side in its initial
694
<acronym>RAM</acronym> disk image file system. This is normally
695
readable by all, but this is normally fixed during installation
696
of this program; file permissions are set so that no-one is able
700
The only remaining weak point is that someone with physical
701
access to the client hard drive might turn off the client
702
computer, read the OpenPGP keys directly from the hard drive,
703
and communicate with the server. To safeguard against this, the
704
server is supposed to notice the client disappearing and stop
705
giving out the encrypted data. Therefore, it is important to
706
set the timeout and checker interval values tightly on the
707
server. See <citerefentry><refentrytitle
708
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
711
It will also help if the checker program on the server is
712
configured to request something from the client which can not be
713
spoofed by someone else on the network, unlike unencrypted
714
<acronym>ICMP</acronym> echo (<quote>ping</quote>) replies.
717
<emphasis>Note</emphasis>: This makes it completely insecure to
718
have <application >Mandos</application> clients which dual-boot
719
to another operating system which is <emphasis>not</emphasis>
720
trusted to keep the initial <acronym>RAM</acronym> disk image
725
386
<refsect1 id="see_also">
726
387
<title>SEE ALSO</title>
728
<citerefentry><refentrytitle>intro</refentrytitle>
729
<manvolnum>8mandos</manvolnum></citerefentry>,
730
<citerefentry><refentrytitle>cryptsetup</refentrytitle>
731
<manvolnum>8</manvolnum></citerefentry>,
732
<citerefentry><refentrytitle>crypttab</refentrytitle>
733
<manvolnum>5</manvolnum></citerefentry>,
734
389
<citerefentry><refentrytitle>mandos</refentrytitle>
735
390
<manvolnum>8</manvolnum></citerefentry>,
736
391
<citerefentry><refentrytitle>password-prompt</refentrytitle>
738
393
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
739
394
<manvolnum>8mandos</manvolnum></citerefentry>
744
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
748
Zeroconf is the network protocol standard used for finding
749
Mandos servers on the local network.
755
<ulink url="http://www.avahi.org/">Avahi</ulink>
759
Avahi is the library this program calls to find Zeroconf
766
<ulink url="http://www.gnu.org/software/gnutls/"
771
GnuTLS is the library this client uses to implement TLS for
772
communicating securely with the server, and at the same time
773
send the public OpenPGP key to the server.
779
<ulink url="http://www.gnupg.org/related_software/gpgme/"
784
GPGME is the library used to decrypt the OpenPGP data sent
791
RFC 4291: <citetitle>IP Version 6 Addressing
792
Architecture</citetitle>
797
<term>Section 2.2: <citetitle>Text Representation of
798
Addresses</citetitle></term>
799
<listitem><para/></listitem>
802
<term>Section 2.5.5.2: <citetitle>IPv4-Mapped IPv6
803
Address</citetitle></term>
804
<listitem><para/></listitem>
807
<term>Section 2.5.6, <citetitle>Link-Local IPv6 Unicast
808
Addresses</citetitle></term>
811
This client uses IPv6 link-local addresses, which are
812
immediately usable since a link-local addresses is
813
automatically assigned to a network interfaces when it
823
RFC 4346: <citetitle>The Transport Layer Security (TLS)
824
Protocol Version 1.1</citetitle>
828
TLS 1.1 is the protocol implemented by GnuTLS.
834
RFC 4880: <citetitle>OpenPGP Message Format</citetitle>
838
The data received from the server is binary encrypted
845
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
850
This is implemented by GnuTLS and used by this program so
851
that OpenPGP keys can be used.
398
<ulink url="http://www.zeroconf.org/">Zeroconf</ulink>
402
<ulink url="http://www.avahi.org/">Avahi</ulink>
407
url="http://www.gnu.org/software/gnutls/">GnuTLS</ulink>
412
url="http://www.gnupg.org/related_software/gpgme/"
417
<citation>RFC 4880: <citetitle>OpenPGP Message
418
Format</citetitle></citation>
422
<citation>RFC 5081: <citetitle>Using OpenPGP Keys for
423
Transport Layer Security</citetitle></citation>
427
<citation>RFC 4291: <citetitle>IP Version 6 Addressing
428
Architecture</citetitle>, section 2.5.6, Link-Local IPv6
429
Unicast Addresses</citation>
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