171
127
communicates with <citerefentry><refentrytitle
172
128
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>
173
129
to get a password. In slightly more detail, this client program
174
brings up network interfaces, uses the interfaces’ IPv6
175
link-local addresses to get network connectivity, uses Zeroconf
176
to find servers on the local network, and communicates with
177
servers using TLS with a raw public key to ensure authenticity
178
and confidentiality. This client program keeps running, trying
179
all servers on the network, until it receives a satisfactory
180
reply or a TERM signal. After all servers have been tried, all
181
servers are periodically retried. If no servers are found it
182
will wait indefinitely for new servers to appear.
185
The network interfaces are selected like this: If any interfaces
186
are specified using the <option>--interface</option> option,
187
those interface are used. Otherwise,
188
<command>&COMMANDNAME;</command> will use all interfaces that
189
are not loopback interfaces, are not point-to-point interfaces,
190
are capable of broadcasting and do not have the NOARP flag (see
191
<citerefentry><refentrytitle>netdevice</refentrytitle>
192
<manvolnum>7</manvolnum></citerefentry>). (If the
193
<option>--connect</option> option is used, point-to-point
194
interfaces and non-broadcast interfaces are accepted.) If any
195
used interfaces are not up and running, they are first taken up
196
(and later taken down again on program exit).
199
Before network interfaces are selected, all <quote>network
200
hooks</quote> are run; see <xref linkend="network-hooks"/>.
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
203
141
This program is not meant to be run directly; it is really meant
204
to be run by other programs in the initial
205
<acronym>RAM</acronym> disk environment; see <xref
206
linkend="overview"/>.
142
to run as a plugin of the <application>Mandos</application>
143
<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.
244
188
assumed to separate the address from the port number.
247
Normally, Zeroconf would be used to locate Mandos servers,
248
in which case this option would only be used when testing
191
This option is normally only useful for testing and
255
198
<term><option>--interface=<replaceable
256
>NAME</replaceable><arg rep='repeat'>,<replaceable
257
>NAME</replaceable></arg></option></term>
199
>NAME</replaceable></option></term>
259
<replaceable>NAME</replaceable><arg rep='repeat'>,<replaceable
260
>NAME</replaceable></arg></option></term>
201
<replaceable>NAME</replaceable></option></term>
263
Comma separated list of network interfaces that will be
264
brought up and scanned for Mandos servers to connect to.
265
The default is the empty string, which will automatically
266
use all appropriate interfaces.
204
Network interface that will be brought up and scanned for
205
Mandos servers to connect to. The default is the empty
206
string, which will automatically choose an appropriate
269
If the <option>--connect</option> option is used, and
270
exactly one interface name is specified (except
271
<quote><literal>none</literal></quote>), this specifies
272
the interface to use to connect to the address given.
210
If the <option>--connect</option> option is used, this
211
specifies the interface to use to connect to the address
275
215
Note that since this program will normally run in the
276
216
initial RAM disk environment, the interface must be an
277
217
interface which exists at that stage. Thus, the interface
278
can normally not be a pseudo-interface such as
279
<quote>br0</quote> or <quote>tun0</quote>; such interfaces
280
will not exist until much later in the boot process, and
281
can not be used by this program, unless created by a
282
<quote>network hook</quote> — see <xref
283
linkend="network-hooks"/>.
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
286
224
<replaceable>NAME</replaceable> can be the string
287
<quote><literal>none</literal></quote>; this will make
288
<command>&COMMANDNAME;</command> only bring up interfaces
289
specified <emphasis>before</emphasis> this string. This
290
is not recommended, and only meant for advanced users.
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
481
345
<title>OVERVIEW</title>
482
346
<xi:include href="../overview.xml"/>
484
This program is the client part. It is run automatically in an
485
initial <acronym>RAM</acronym> disk environment.
488
In an initial <acronym>RAM</acronym> disk environment using
489
<citerefentry><refentrytitle>systemd</refentrytitle>
490
<manvolnum>1</manvolnum></citerefentry>, this program is started
491
by the <application>Mandos</application> <citerefentry>
492
<refentrytitle>password-agent</refentrytitle>
493
<manvolnum>8mandos</manvolnum></citerefentry>, which in turn is
494
started automatically by the <citerefentry>
495
<refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum>
496
</citerefentry> <quote>Password Agent</quote> system.
499
In the case of a non-<citerefentry>
500
<refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum>
501
</citerefentry> environment, this program is started as a plugin
502
of the <application>Mandos</application> <citerefentry>
503
<refentrytitle>plugin-runner</refentrytitle>
504
<manvolnum>8mandos</manvolnum></citerefentry>, which runs in the
505
initial <acronym>RAM</acronym> disk environment because it is
506
specified as a <quote>keyscript</quote> in the <citerefentry>
507
<refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
508
</citerefentry> file.
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.
511
354
This program could, theoretically, be used as a keyscript in
512
355
<filename>/etc/crypttab</filename>, but it would then be
513
356
impossible to enter a password for the encrypted root disk at
514
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
523
371
server could be found and the password received from it could be
524
372
successfully decrypted and output on standard output. The
525
373
program will exit with a non-zero exit status only if a critical
526
error occurs. Otherwise, it will forever connect to any
527
discovered <application>Mandos</application> servers, trying to
528
get a decryptable password and print it.
374
error occurs. Otherwise, it will forever connect to new
375
<application>Mandos</application> servers as they appear, trying
376
to get a decryptable password and print it.
532
380
<refsect1 id="environment">
533
381
<title>ENVIRONMENT</title>
536
<term><envar>MANDOSPLUGINHELPERDIR</envar></term>
539
This environment variable will be assumed to contain the
540
directory containing any helper executables. The use and
541
nature of these helper executables, if any, is purposely
548
This program does not use any other environment variables, not
549
even the ones provided by <citerefentry><refentrytitle
383
This program does not use any environment variables, not even
384
the ones provided by <citerefentry><refentrytitle
550
385
>cryptsetup</refentrytitle><manvolnum>8</manvolnum>
555
<refsect1 id="network-hooks">
556
<title>NETWORK HOOKS</title>
558
If a network interface like a bridge or tunnel is required to
559
find a Mandos server, this requires the interface to be up and
560
running before <command>&COMMANDNAME;</command> starts looking
561
for Mandos servers. This can be accomplished by creating a
562
<quote>network hook</quote> program, and placing it in a special
566
Before the network is used (and again before program exit), any
567
runnable programs found in the network hook directory are run
568
with the argument <quote><literal>start</literal></quote> or
569
<quote><literal>stop</literal></quote>. This should bring up or
570
down, respectively, any network interface which
571
<command>&COMMANDNAME;</command> should use.
573
<refsect2 id="hook-requirements">
574
<title>REQUIREMENTS</title>
576
A network hook must be an executable file, and its name must
577
consist entirely of upper and lower case letters, digits,
578
underscores, periods, and hyphens.
581
A network hook will receive one argument, which can be one of
586
<term><literal>start</literal></term>
589
This should make the network hook create (if necessary)
590
and bring up a network interface.
595
<term><literal>stop</literal></term>
598
This should make the network hook take down a network
599
interface, and delete it if it did not exist previously.
604
<term><literal>files</literal></term>
607
This should make the network hook print, <emphasis>one
608
file per line</emphasis>, all the files needed for it to
609
run. (These files will be copied into the initial RAM
610
filesystem.) Typical use is for a network hook which is
611
a shell script to print its needed binaries.
614
It is not necessary to print any non-executable files
615
already in the network hook directory, these will be
616
copied implicitly if they otherwise satisfy the name
622
<term><literal>modules</literal></term>
625
This should make the network hook print, <emphasis>on
626
separate lines</emphasis>, all the kernel modules needed
627
for it to run. (These modules will be copied into the
628
initial RAM filesystem.) For instance, a tunnel
630
<quote><literal>tun</literal></quote> module.
636
The network hook will be provided with a number of environment
641
<term><envar>MANDOSNETHOOKDIR</envar></term>
644
The network hook directory, specified to
645
<command>&COMMANDNAME;</command> by the
646
<option>--network-hook-dir</option> option. Note: this
647
should <emphasis>always</emphasis> be used by the
648
network hook to refer to itself or any files in the hook
649
directory it may require.
654
<term><envar>DEVICE</envar></term>
657
The network interfaces, as specified to
658
<command>&COMMANDNAME;</command> by the
659
<option>--interface</option> option, combined to one
660
string and separated by commas. If this is set, and
661
does not contain the interface a hook will bring up,
662
there is no reason for a hook to continue.
667
<term><envar>MODE</envar></term>
670
This will be the same as the first argument;
671
i.e. <quote><literal>start</literal></quote>,
672
<quote><literal>stop</literal></quote>,
673
<quote><literal>files</literal></quote>, or
674
<quote><literal>modules</literal></quote>.
679
<term><envar>VERBOSITY</envar></term>
682
This will be the <quote><literal>1</literal></quote> if
683
the <option>--debug</option> option is passed to
684
<command>&COMMANDNAME;</command>, otherwise
685
<quote><literal>0</literal></quote>.
690
<term><envar>DELAY</envar></term>
693
This will be the same as the <option>--delay</option>
694
option passed to <command>&COMMANDNAME;</command>. Is
695
only set if <envar>MODE</envar> is
696
<quote><literal>start</literal></quote> or
697
<quote><literal>stop</literal></quote>.
702
<term><envar>CONNECT</envar></term>
705
This will be the same as the <option>--connect</option>
706
option passed to <command>&COMMANDNAME;</command>. Is
707
only set if <option>--connect</option> is passed and
708
<envar>MODE</envar> is
709
<quote><literal>start</literal></quote> or
710
<quote><literal>stop</literal></quote>.
716
A hook may not read from standard input, and should be
717
restrictive in printing to standard output or standard error
718
unless <varname>VERBOSITY</varname> is
719
<quote><literal>1</literal></quote>.
724
390
<refsect1 id="files">
725
391
<title>FILES</title>
742
<term><filename>/conf/conf.d/mandos/tls-pubkey.pem</filename
744
<term><filename>/conf/conf.d/mandos/tls-privkey.pem</filename
748
Public and private raw key files, in <quote>PEM</quote>
749
format. These are the default file names, they can be
750
changed with the <option>--tls-pubkey</option> and
751
<option>--tls-privkey</option> options.
757
class="directory">/lib/mandos/network-hooks.d</filename></term>
760
Directory where network hooks are located. Change this
761
with the <option>--network-hook-dir</option> option. See
762
<xref linkend="network-hooks"/>.
771
<xi:include href="../bugs.xml"/>
410
<!-- <refsect1 id="bugs"> -->
411
<!-- <title>BUGS</title> -->
774
416
<refsect1 id="example">
775
417
<title>EXAMPLE</title>
777
419
Note that normally, command line options will not be given
778
directly, but passed on via the program responsible for starting
779
this program; see <xref linkend="overview"/>.
420
directly, but via options for the Mandos <citerefentry
421
><refentrytitle>plugin-runner</refentrytitle>
422
<manvolnum>8mandos</manvolnum></citerefentry>.
781
424
<informalexample>
783
Normal invocation needs no options, if the network interfaces
784
can be automatically determined:
426
Normal invocation needs no options, if the network interface
427
is <quote>eth0</quote>:
787
430
<userinput>&COMMANDNAME;</userinput>
850
493
The only remaining weak point is that someone with physical
851
494
access to the client hard drive might turn off the client
852
computer, read the OpenPGP and TLS keys directly from the hard
853
drive, and communicate with the server. To safeguard against
854
this, the server is supposed to notice the client disappearing
855
and stop giving out the encrypted data. Therefore, it is
856
important to set the timeout and checker interval values tightly
857
on the server. See <citerefentry><refentrytitle
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
858
501
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
861
504
It will also help if the checker program on the server is
862
505
configured to request something from the client which can not be
863
spoofed by someone else on the network, like SSH server key
864
fingerprints, and unlike unencrypted <acronym>ICMP</acronym>
865
echo (<quote>ping</quote>) replies.
506
spoofed by someone else on the network, unlike unencrypted
507
<acronym>ICMP</acronym> echo (<quote>ping</quote>) replies.
868
510
<emphasis>Note</emphasis>: This makes it completely insecure to