166
137
communicates with <citerefentry><refentrytitle
167
138
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>
168
139
to get a password. In slightly more detail, this client program
169
brings up network interfaces, uses the interfaces’ IPv6
170
link-local addresses to get network connectivity, uses Zeroconf
171
to find servers on the local network, and communicates with
172
servers using TLS with a raw public key to ensure authenticity
173
and confidentiality. This client program keeps running, trying
174
all servers on the network, until it receives a satisfactory
175
reply or a TERM signal. After all servers have been tried, all
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
176
147
servers are periodically retried. If no servers are found it
177
148
will wait indefinitely for new servers to appear.
180
The network interfaces are selected like this: If any interfaces
181
are specified using the <option>--interface</option> option,
182
those interface are used. Otherwise,
183
<command>&COMMANDNAME;</command> will use all interfaces that
184
are not loopback interfaces, are not point-to-point interfaces,
185
are capable of broadcasting and do not have the NOARP flag (see
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
186
157
<citerefentry><refentrytitle>netdevice</refentrytitle>
187
158
<manvolnum>7</manvolnum></citerefentry>). (If the
188
159
<option>--connect</option> option is used, point-to-point
189
interfaces and non-broadcast interfaces are accepted.) If any
190
used interfaces are not up and running, they are first taken up
191
(and later taken down again on program exit).
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
194
Before network interfaces are selected, all <quote>network
167
Before a network interface is selected, all <quote>network
195
168
hooks</quote> are run; see <xref linkend="network-hooks"/>.
198
171
This program is not meant to be run directly; it is really meant
199
to be run by other programs in the initial
200
<acronym>RAM</acronym> disk environment; see <xref
201
linkend="overview"/>.
172
to run as a plugin of the <application>Mandos</application>
173
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
174
<manvolnum>8mandos</manvolnum></citerefentry>, which runs in the
175
initial <acronym>RAM</acronym> disk environment because it is
176
specified as a <quote>keyscript</quote> in the <citerefentry>
177
<refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
178
</citerefentry> file.
216
193
<title>OPTIONS</title>
218
195
This program is commonly not invoked from the command line; it
219
is normally started by another program as described in <xref
220
linkend="description"/>. Any command line options this program
221
accepts are therefore normally provided by the invoking program,
196
is normally started by the <application>Mandos</application>
197
plugin runner, see <citerefentry><refentrytitle
198
>plugin-runner</refentrytitle><manvolnum>8mandos</manvolnum>
199
</citerefentry>. Any command line options this program accepts
200
are therefore normally provided by the plugin runner, and not
239
218
assumed to separate the address from the port number.
242
Normally, Zeroconf would be used to locate Mandos servers,
243
in which case this option would only be used when testing
221
This option is normally only useful for testing and
250
228
<term><option>--interface=<replaceable
251
>NAME</replaceable><arg rep='repeat'>,<replaceable
252
>NAME</replaceable></arg></option></term>
229
>NAME</replaceable></option></term>
254
<replaceable>NAME</replaceable><arg rep='repeat'>,<replaceable
255
>NAME</replaceable></arg></option></term>
231
<replaceable>NAME</replaceable></option></term>
258
Comma separated list of network interfaces that will be
259
brought up and scanned for Mandos servers to connect to.
260
The default is the empty string, which will automatically
261
use all appropriate interfaces.
234
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
264
If the <option>--connect</option> option is used, and
265
exactly one interface name is specified (except
266
<quote><literal>none</literal></quote>), this specifies
267
the interface to use to connect to the address given.
240
If the <option>--connect</option> option is used, this
241
specifies the interface to use to connect to the address
270
245
Note that since this program will normally run in the
271
246
initial RAM disk environment, the interface must be an
272
247
interface which exists at that stage. Thus, the interface
273
can normally not be a pseudo-interface such as
274
<quote>br0</quote> or <quote>tun0</quote>; such interfaces
275
will not exist until much later in the boot process, and
276
can not be used by this program, unless created by a
277
<quote>network hook</quote> — see <xref
278
linkend="network-hooks"/>.
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"/>.
281
255
<replaceable>NAME</replaceable> can be the string
282
<quote><literal>none</literal></quote>; this will make
283
<command>&COMMANDNAME;</command> only bring up interfaces
284
specified <emphasis>before</emphasis> this string. This
285
is not recommended, and only meant for advanced users.
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
319
<term><option>--tls-pubkey=<replaceable
320
>FILE</replaceable></option></term>
322
<replaceable>FILE</replaceable></option></term>
325
TLS raw public key file name. The default name is
326
<quote><filename>/conf/conf.d/mandos/tls-pubkey.pem</filename
333
<term><option>--tls-privkey=<replaceable
334
>FILE</replaceable></option></term>
336
<replaceable>FILE</replaceable></option></term>
339
TLS secret key file name. The default name is
340
<quote><filename>/conf/conf.d/mandos/tls-privkey.pem</filename
347
293
<term><option>--priority=<replaceable
348
294
>STRING</replaceable></option></term>
360
306
Sets the number of bits to use for the prime number in the
361
TLS Diffie-Hellman key exchange. The default value is
362
selected automatically based on the GnuTLS security
363
profile set in its priority string. Note that if the
364
<option>--dh-params</option> option is used, the values
365
from that file will be used instead.
371
<term><option>--dh-params=<replaceable
372
>FILE</replaceable></option></term>
375
Specifies a PEM-encoded PKCS#3 file to read the parameters
376
needed by the TLS Diffie-Hellman key exchange from. If
377
this option is not given, or if the file for some reason
378
could not be used, the parameters will be generated on
379
startup, which will take some time and processing power.
380
Those using servers running under time, power or processor
381
constraints may want to generate such a file in advance
307
TLS Diffie-Hellman key exchange. Default is 1024.
476
401
<title>OVERVIEW</title>
477
402
<xi:include href="../overview.xml"/>
479
This program is the client part. It is run automatically in an
480
initial <acronym>RAM</acronym> disk environment.
483
In an initial <acronym>RAM</acronym> disk environment using
484
<citerefentry><refentrytitle>systemd</refentrytitle>
485
<manvolnum>1</manvolnum></citerefentry>, this program is started
486
by the <application>Mandos</application> <citerefentry>
487
<refentrytitle>password-agent</refentrytitle>
488
<manvolnum>8mandos</manvolnum></citerefentry>, which in turn is
489
started automatically by the <citerefentry>
490
<refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum>
491
</citerefentry> <quote>Password Agent</quote> system.
494
In the case of a non-<citerefentry>
495
<refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum>
496
</citerefentry> environment, this program is started as a plugin
497
of the <application>Mandos</application> <citerefentry>
498
<refentrytitle>plugin-runner</refentrytitle>
499
<manvolnum>8mandos</manvolnum></citerefentry>, which runs in the
500
initial <acronym>RAM</acronym> disk environment because it is
501
specified as a <quote>keyscript</quote> in the <citerefentry>
502
<refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
503
</citerefentry> file.
404
This program is the client part. It is a plugin started by
405
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
406
<manvolnum>8mandos</manvolnum></citerefentry> which will run in
407
an initial <acronym>RAM</acronym> disk environment.
506
410
This program could, theoretically, be used as a keyscript in
507
411
<filename>/etc/crypttab</filename>, but it would then be
508
412
impossible to enter a password for the encrypted root disk at
509
413
the console, since this program does not read from the console
414
at all. This is why a separate plugin runner (<citerefentry>
415
<refentrytitle>plugin-runner</refentrytitle>
416
<manvolnum>8mandos</manvolnum></citerefentry>) is used to run
417
both this program and others in in parallel,
418
<emphasis>one</emphasis> of which (<citerefentry>
419
<refentrytitle>password-prompt</refentrytitle>
420
<manvolnum>8mandos</manvolnum></citerefentry>) will prompt for
421
passwords on the system console.
527
438
<refsect1 id="environment">
528
439
<title>ENVIRONMENT</title>
531
<term><envar>MANDOSPLUGINHELPERDIR</envar></term>
534
This environment variable will be assumed to contain the
535
directory containing any helper executables. The use and
536
nature of these helper executables, if any, is purposely
543
This program does not use any other environment variables, not
544
even the ones provided by <citerefentry><refentrytitle
441
This program does not use any environment variables, not even
442
the ones provided by <citerefentry><refentrytitle
545
443
>cryptsetup</refentrytitle><manvolnum>8</manvolnum>
649
547
<term><envar>DEVICE</envar></term>
652
The network interfaces, as specified to
550
The network interface, as specified to
653
551
<command>&COMMANDNAME;</command> by the
654
<option>--interface</option> option, combined to one
655
string and separated by commas. If this is set, and
656
does not contain the interface a hook will bring up,
657
there is no reason for a hook to continue.
552
<option>--interface</option> option. If this is not the
553
interface a hook will bring up, there is no reason for a
766
<xi:include href="../bugs.xml"/>
647
<!-- <refsect1 id="bugs"> -->
648
<!-- <title>BUGS</title> -->
769
653
<refsect1 id="example">
770
654
<title>EXAMPLE</title>
772
656
Note that normally, command line options will not be given
773
directly, but passed on via the program responsible for starting
774
this program; see <xref linkend="overview"/>.
657
directly, but via options for the Mandos <citerefentry
658
><refentrytitle>plugin-runner</refentrytitle>
659
<manvolnum>8mandos</manvolnum></citerefentry>.
776
661
<informalexample>
778
Normal invocation needs no options, if the network interfaces
663
Normal invocation needs no options, if the network interface
779
664
can be automatically determined:
794
679
</informalexample>
795
680
<informalexample>
797
Run in debug mode, and use custom keys:
682
Run in debug mode, and use a custom key:
801
686
<!-- do not wrap this line -->
802
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt --tls-pubkey keydir/tls-pubkey.pem --tls-privkey keydir/tls-privkey.pem</userinput>
687
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt</userinput>
805
690
</informalexample>
806
691
<informalexample>
808
Run in debug mode, with custom keys, and do not use Zeroconf
693
Run in debug mode, with a custom key, and do not use Zeroconf
809
694
to locate a server; connect directly to the IPv6 link-local
810
695
address <quote><systemitem class="ipaddress"
811
696
>fe80::aede:48ff:fe71:f6f2</systemitem></quote>, port 4711,
845
730
The only remaining weak point is that someone with physical
846
731
access to the client hard drive might turn off the client
847
computer, read the OpenPGP and TLS keys directly from the hard
848
drive, and communicate with the server. To safeguard against
849
this, the server is supposed to notice the client disappearing
850
and stop giving out the encrypted data. Therefore, it is
851
important to set the timeout and checker interval values tightly
852
on the server. See <citerefentry><refentrytitle
732
computer, read the OpenPGP keys directly from the hard drive,
733
and communicate with the server. To safeguard against this, the
734
server is supposed to notice the client disappearing and stop
735
giving out the encrypted data. Therefore, it is important to
736
set the timeout and checker interval values tightly on the
737
server. See <citerefentry><refentrytitle
853
738
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
856
741
It will also help if the checker program on the server is
857
742
configured to request something from the client which can not be
858
spoofed by someone else on the network, like SSH server key
859
fingerprints, and unlike unencrypted <acronym>ICMP</acronym>
860
echo (<quote>ping</quote>) replies.
743
spoofed by someone else on the network, unlike unencrypted
744
<acronym>ICMP</acronym> echo (<quote>ping</quote>) replies.
863
747
<emphasis>Note</emphasis>: This makes it completely insecure to
990
RFC 7250: <citetitle>Using Raw Public Keys in Transport
991
Layer Security (TLS) and Datagram Transport Layer Security
996
This is implemented by GnuTLS in version 3.6.6 and is, if
997
present, used by this program so that raw public keys can be
1004
RFC 6091: <citetitle>Using OpenPGP Keys for Transport Layer
875
RFC 5081: <citetitle>Using OpenPGP Keys for Transport Layer
1005
876
Security</citetitle>
1009
This is implemented by GnuTLS before version 3.6.0 and is,
1010
if present, used by this program so that OpenPGP keys can be
880
This is implemented by GnuTLS and used by this program so
881
that OpenPGP keys can be used.