121
165
<command>&COMMANDNAME;</command> is a client program that
122
166
communicates with <citerefentry><refentrytitle
123
167
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>
124
to get a password. It uses IPv6 link-local addresses to get
125
network connectivity, Zeroconf to find servers, and TLS with an
126
OpenPGP key to ensure authenticity and confidentiality. It
127
keeps running, trying all servers on the network, until it
128
receives a satisfactory reply or a TERM signal is received.
168
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
176
servers are periodically retried. If no servers are found it
177
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
186
<citerefentry><refentrytitle>netdevice</refentrytitle>
187
<manvolnum>7</manvolnum></citerefentry>). (If the
188
<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).
194
Before network interfaces are selected, all <quote>network
195
hooks</quote> are run; see <xref linkend="network-hooks"/>.
131
198
This program is not meant to be run directly; it is really meant
132
to run as a plugin of the <application>Mandos</application>
133
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
134
<manvolnum>8mandos</manvolnum></citerefentry>, which runs in the
135
initial <acronym>RAM</acronym> disk environment because it is
136
specified as a <quote>keyscript</quote> in the <citerefentry>
137
<refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
138
</citerefentry> file.
199
to be run by other programs in the initial
200
<acronym>RAM</acronym> disk environment; see <xref
201
linkend="overview"/>.
178
239
assumed to separate the address from the port number.
181
This option is normally only useful for testing and
242
Normally, Zeroconf would be used to locate Mandos servers,
243
in which case this option would only be used when testing
188
<term><option>--interface=
189
<replaceable>NAME</replaceable></option></term>
250
<term><option>--interface=<replaceable
251
>NAME</replaceable><arg rep='repeat'>,<replaceable
252
>NAME</replaceable></arg></option></term>
191
<replaceable>NAME</replaceable></option></term>
254
<replaceable>NAME</replaceable><arg rep='repeat'>,<replaceable
255
>NAME</replaceable></arg></option></term>
194
Network interface that will be brought up and scanned for
195
Mandos servers to connect to. The default it
196
<quote><literal>eth0</literal></quote>.
199
If the <option>--connect</option> option is used, this
200
specifies the interface to use to connect to the address
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.
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.
270
Note that since this program will normally run in the
271
initial RAM disk environment, the interface must be an
272
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"/>.
281
<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.
248
360
Sets the number of bits to use for the prime number in the
249
TLS Diffie-Hellman key exchange. Default is 1024.
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
388
<term><option>--delay=<replaceable
389
>SECONDS</replaceable></option></term>
392
After bringing a network interface up, the program waits
393
for the interface to arrive in a <quote>running</quote>
394
state before proceeding. During this time, the kernel log
395
level will be lowered to reduce clutter on the system
396
console, alleviating any other plugins which might be
397
using the system console. This option sets the upper
398
limit of seconds to wait. The default is 2.5 seconds.
404
<term><option>--retry=<replaceable
405
>SECONDS</replaceable></option></term>
408
All Mandos servers are tried repeatedly until a password
409
is received. This value specifies, in seconds, how long
410
between each successive try <emphasis>for the same
411
server</emphasis>. The default is 10 seconds.
417
<term><option>--network-hook-dir=<replaceable
418
>DIR</replaceable></option></term>
421
Network hook directory. The default directory is
422
<quote><filename class="directory"
423
>/lib/mandos/network-hooks.d</filename></quote>.
302
476
<title>OVERVIEW</title>
303
477
<xi:include href="../overview.xml"/>
305
This program is the client part. It is a plugin started by
306
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
307
<manvolnum>8mandos</manvolnum></citerefentry> which will run in
308
an initial <acronym>RAM</acronym> disk environment.
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.
311
506
This program could, theoretically, be used as a keyscript in
312
507
<filename>/etc/crypttab</filename>, but it would then be
313
508
impossible to enter a password for the encrypted root disk at
314
509
the console, since this program does not read from the console
315
at all. This is why a separate plugin runner (<citerefentry>
316
<refentrytitle>plugin-runner</refentrytitle>
317
<manvolnum>8mandos</manvolnum></citerefentry>) is used to run
318
both this program and others in in parallel,
319
<emphasis>one</emphasis> of which will prompt for passwords on
328
518
server could be found and the password received from it could be
329
519
successfully decrypted and output on standard output. The
330
520
program will exit with a non-zero exit status only if a critical
331
error occurs. Otherwise, it will forever connect to new
332
<application>Mandos</application> servers as they appear, trying
333
to get a decryptable password and print it.
521
error occurs. Otherwise, it will forever connect to any
522
discovered <application>Mandos</application> servers, trying to
523
get a decryptable password and print it.
337
527
<refsect1 id="environment">
338
528
<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
340
This program does not use any environment variables, not even
341
the ones provided by <citerefentry><refentrytitle
543
This program does not use any other environment variables, not
544
even the ones provided by <citerefentry><refentrytitle
342
545
>cryptsetup</refentrytitle><manvolnum>8</manvolnum>
550
<refsect1 id="network-hooks">
551
<title>NETWORK HOOKS</title>
553
If a network interface like a bridge or tunnel is required to
554
find a Mandos server, this requires the interface to be up and
555
running before <command>&COMMANDNAME;</command> starts looking
556
for Mandos servers. This can be accomplished by creating a
557
<quote>network hook</quote> program, and placing it in a special
561
Before the network is used (and again before program exit), any
562
runnable programs found in the network hook directory are run
563
with the argument <quote><literal>start</literal></quote> or
564
<quote><literal>stop</literal></quote>. This should bring up or
565
down, respectively, any network interface which
566
<command>&COMMANDNAME;</command> should use.
568
<refsect2 id="hook-requirements">
569
<title>REQUIREMENTS</title>
571
A network hook must be an executable file, and its name must
572
consist entirely of upper and lower case letters, digits,
573
underscores, periods, and hyphens.
576
A network hook will receive one argument, which can be one of
581
<term><literal>start</literal></term>
584
This should make the network hook create (if necessary)
585
and bring up a network interface.
590
<term><literal>stop</literal></term>
593
This should make the network hook take down a network
594
interface, and delete it if it did not exist previously.
599
<term><literal>files</literal></term>
602
This should make the network hook print, <emphasis>one
603
file per line</emphasis>, all the files needed for it to
604
run. (These files will be copied into the initial RAM
605
filesystem.) Typical use is for a network hook which is
606
a shell script to print its needed binaries.
609
It is not necessary to print any non-executable files
610
already in the network hook directory, these will be
611
copied implicitly if they otherwise satisfy the name
617
<term><literal>modules</literal></term>
620
This should make the network hook print, <emphasis>on
621
separate lines</emphasis>, all the kernel modules needed
622
for it to run. (These modules will be copied into the
623
initial RAM filesystem.) For instance, a tunnel
625
<quote><literal>tun</literal></quote> module.
631
The network hook will be provided with a number of environment
636
<term><envar>MANDOSNETHOOKDIR</envar></term>
639
The network hook directory, specified to
640
<command>&COMMANDNAME;</command> by the
641
<option>--network-hook-dir</option> option. Note: this
642
should <emphasis>always</emphasis> be used by the
643
network hook to refer to itself or any files in the hook
644
directory it may require.
649
<term><envar>DEVICE</envar></term>
652
The network interfaces, as specified to
653
<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.
662
<term><envar>MODE</envar></term>
665
This will be the same as the first argument;
666
i.e. <quote><literal>start</literal></quote>,
667
<quote><literal>stop</literal></quote>,
668
<quote><literal>files</literal></quote>, or
669
<quote><literal>modules</literal></quote>.
674
<term><envar>VERBOSITY</envar></term>
677
This will be the <quote><literal>1</literal></quote> if
678
the <option>--debug</option> option is passed to
679
<command>&COMMANDNAME;</command>, otherwise
680
<quote><literal>0</literal></quote>.
685
<term><envar>DELAY</envar></term>
688
This will be the same as the <option>--delay</option>
689
option passed to <command>&COMMANDNAME;</command>. Is
690
only set if <envar>MODE</envar> is
691
<quote><literal>start</literal></quote> or
692
<quote><literal>stop</literal></quote>.
697
<term><envar>CONNECT</envar></term>
700
This will be the same as the <option>--connect</option>
701
option passed to <command>&COMMANDNAME;</command>. Is
702
only set if <option>--connect</option> is passed and
703
<envar>MODE</envar> is
704
<quote><literal>start</literal></quote> or
705
<quote><literal>stop</literal></quote>.
711
A hook may not read from standard input, and should be
712
restrictive in printing to standard output or standard error
713
unless <varname>VERBOSITY</varname> is
714
<quote><literal>1</literal></quote>.
719
<refsect1 id="files">
348
720
<title>FILES</title>
737
<term><filename>/conf/conf.d/mandos/tls-pubkey.pem</filename
739
<term><filename>/conf/conf.d/mandos/tls-privkey.pem</filename
743
Public and private raw key files, in <quote>PEM</quote>
744
format. These are the default file names, they can be
745
changed with the <option>--tls-pubkey</option> and
746
<option>--tls-privkey</option> options.
752
class="directory">/lib/mandos/network-hooks.d</filename></term>
755
Directory where network hooks are located. Change this
756
with the <option>--network-hook-dir</option> option. See
757
<xref linkend="network-hooks"/>.
367
<!-- <refsect1 id="bugs"> -->
368
<!-- <title>BUGS</title> -->
766
<xi:include href="../bugs.xml"/>
373
769
<refsect1 id="example">
374
770
<title>EXAMPLE</title>
376
772
Note that normally, command line options will not be given
377
directly, but via options for the Mandos <citerefentry
378
><refentrytitle>plugin-runner</refentrytitle>
379
<manvolnum>8mandos</manvolnum></citerefentry>.
773
directly, but passed on via the program responsible for starting
774
this program; see <xref linkend="overview"/>.
381
776
<informalexample>
383
Normal invocation needs no options, if the network interface
384
is <quote>eth0</quote>:
778
Normal invocation needs no options, if the network interfaces
779
can be automatically determined:
387
782
<userinput>&COMMANDNAME;</userinput>
399
794
</informalexample>
400
795
<informalexample>
402
Run in debug mode, and use a custom key:
797
Run in debug mode, and use custom keys:
406
801
<!-- do not wrap this line -->
407
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt</userinput>
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>
410
805
</informalexample>
411
806
<informalexample>
413
Run in debug mode, with a custom key, and do not use Zeroconf
414
to locate a server; connect directly to the IPv6 address
415
<quote><systemitem class="ipaddress"
416
>2001:db8:f983:bd0b:30de:ae4a:71f2:f672</systemitem></quote>,
417
port 4711, using interface eth2:
808
Run in debug mode, with custom keys, and do not use Zeroconf
809
to locate a server; connect directly to the IPv6 link-local
810
address <quote><systemitem class="ipaddress"
811
>fe80::aede:48ff:fe71:f6f2</systemitem></quote>, port 4711,
812
using interface eth2:
421
816
<!-- do not wrap this line -->
422
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt --connect 2001:db8:f983:bd0b:30de:ae4a:71f2:f672:4711 --interface eth2</userinput>
817
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt --tls-pubkey keydir/tls-pubkey.pem --tls-privkey keydir/tls-privkey.pem --connect fe80::aede:48ff:fe71:f6f2:4711 --interface eth2</userinput>
425
820
</informalexample>
450
845
The only remaining weak point is that someone with physical
451
846
access to the client hard drive might turn off the client
452
computer, read the OpenPGP keys directly from the hard drive,
453
and communicate with the server. To safeguard against this, the
454
server is supposed to notice the client disappearing and stop
455
giving out the encrypted data. Therefore, it is important to
456
set the timeout and checker interval values tightly on the
457
server. See <citerefentry><refentrytitle
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
458
853
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
461
856
It will also help if the checker program on the server is
462
857
configured to request something from the client which can not be
463
spoofed by someone else on the network, unlike unencrypted
464
<acronym>ICMP</acronym> echo (<quote>ping</quote>) replies.
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.
467
863
<emphasis>Note</emphasis>: This makes it completely insecure to