126
165
<command>&COMMANDNAME;</command> is a client program that
127
166
communicates with <citerefentry><refentrytitle
128
167
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>
129
to get a password. It uses IPv6 link-local addresses to get
130
network connectivity, Zeroconf to find servers, and TLS with an
131
OpenPGP key to ensure authenticity and confidentiality. It
132
keeps running, trying all servers on the network, until it
133
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"/>.
136
198
This program is not meant to be run directly; it is really meant
137
to run as a plugin of the <application>Mandos</application>
138
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
139
<manvolnum>8mandos</manvolnum></citerefentry>, which runs in the
140
initial <acronym>RAM</acronym> disk environment because it is
141
specified as a <quote>keyscript</quote> in the <citerefentry>
142
<refentrytitle>crypttab</refentrytitle><manvolnum>5</manvolnum>
143
</citerefentry> file.
199
to be run by other programs in the initial
200
<acronym>RAM</acronym> disk environment; see <xref
201
linkend="overview"/>.
183
239
assumed to separate the address from the port number.
186
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
193
<term><option>--interface=
194
<replaceable>NAME</replaceable></option></term>
250
<term><option>--interface=<replaceable
251
>NAME</replaceable><arg rep='repeat'>,<replaceable
252
>NAME</replaceable></arg></option></term>
196
<replaceable>NAME</replaceable></option></term>
254
<replaceable>NAME</replaceable><arg rep='repeat'>,<replaceable
255
>NAME</replaceable></arg></option></term>
199
Network interface that will be brought up and scanned for
200
Mandos servers to connect to. The default it
201
<quote><literal>eth0</literal></quote>.
204
If the <option>--connect</option> option is used, this
205
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.
323
476
<title>OVERVIEW</title>
324
477
<xi:include href="../overview.xml"/>
326
This program is the client part. It is a plugin started by
327
<citerefentry><refentrytitle>plugin-runner</refentrytitle>
328
<manvolnum>8mandos</manvolnum></citerefentry> which will run in
329
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.
332
506
This program could, theoretically, be used as a keyscript in
333
507
<filename>/etc/crypttab</filename>, but it would then be
334
508
impossible to enter a password for the encrypted root disk at
335
509
the console, since this program does not read from the console
336
at all. This is why a separate plugin runner (<citerefentry>
337
<refentrytitle>plugin-runner</refentrytitle>
338
<manvolnum>8mandos</manvolnum></citerefentry>) is used to run
339
both this program and others in in parallel,
340
<emphasis>one</emphasis> of which will prompt for passwords on
349
518
server could be found and the password received from it could be
350
519
successfully decrypted and output on standard output. The
351
520
program will exit with a non-zero exit status only if a critical
352
error occurs. Otherwise, it will forever connect to new
353
<application>Mandos</application> servers as they appear, trying
354
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.
358
527
<refsect1 id="environment">
359
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
361
This program does not use any environment variables, not even
362
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
363
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>.
368
719
<refsect1 id="files">
369
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"/>.
388
<!-- <refsect1 id="bugs"> -->
389
<!-- <title>BUGS</title> -->
766
<xi:include href="../bugs.xml"/>
394
769
<refsect1 id="example">
395
770
<title>EXAMPLE</title>
397
772
Note that normally, command line options will not be given
398
directly, but via options for the Mandos <citerefentry
399
><refentrytitle>plugin-runner</refentrytitle>
400
<manvolnum>8mandos</manvolnum></citerefentry>.
773
directly, but passed on via the program responsible for starting
774
this program; see <xref linkend="overview"/>.
402
776
<informalexample>
404
Normal invocation needs no options, if the network interface
405
is <quote>eth0</quote>:
778
Normal invocation needs no options, if the network interfaces
779
can be automatically determined:
408
782
<userinput>&COMMANDNAME;</userinput>
420
794
</informalexample>
421
795
<informalexample>
423
Run in debug mode, and use a custom key:
797
Run in debug mode, and use custom keys:
427
801
<!-- do not wrap this line -->
428
<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>
431
805
</informalexample>
432
806
<informalexample>
434
Run in debug mode, with a custom key, and do not use Zeroconf
435
to locate a server; connect directly to the IPv6 address
436
<quote><systemitem class="ipaddress"
437
>2001:db8:f983:bd0b:30de:ae4a:71f2:f672</systemitem></quote>,
438
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:
442
816
<!-- do not wrap this line -->
443
<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>
446
820
</informalexample>
471
845
The only remaining weak point is that someone with physical
472
846
access to the client hard drive might turn off the client
473
computer, read the OpenPGP keys directly from the hard drive,
474
and communicate with the server. To safeguard against this, the
475
server is supposed to notice the client disappearing and stop
476
giving out the encrypted data. Therefore, it is important to
477
set the timeout and checker interval values tightly on the
478
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
479
853
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
482
856
It will also help if the checker program on the server is
483
857
configured to request something from the client which can not be
484
spoofed by someone else on the network, unlike unencrypted
485
<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.
488
863
<emphasis>Note</emphasis>: This makes it completely insecure to