127
165
communicates with <citerefentry><refentrytitle
128
166
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>
129
167
to get a password. In slightly more detail, this client program
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
168
brings up network interfaces, uses the interfaces’ IPv6
169
link-local addresses to get network connectivity, uses Zeroconf
170
to find servers on the local network, and communicates with
171
servers using TLS with a raw public key to ensure authenticity
172
and confidentiality. This client program keeps running, trying
173
all servers on the network, until it receives a satisfactory
174
reply or a TERM signal. After all servers have been tried, all
175
servers are periodically retried. If no servers are found it
176
will wait indefinitely for new servers to appear.
179
The network interfaces are selected like this: If any interfaces
180
are specified using the <option>--interface</option> option,
181
those interface are used. Otherwise,
182
<command>&COMMANDNAME;</command> will use all interfaces that
183
are not loopback interfaces, are not point-to-point interfaces,
184
are capable of broadcasting and do not have the NOARP flag (see
185
<citerefentry><refentrytitle>netdevice</refentrytitle>
186
<manvolnum>7</manvolnum></citerefentry>). (If the
187
<option>--connect</option> option is used, point-to-point
188
interfaces and non-broadcast interfaces are accepted.) If any
189
used interfaces are not up and running, they are first taken up
190
(and later taken down again on program exit).
193
Before network interfaces are selected, all <quote>network
194
hooks</quote> are run; see <xref linkend="network-hooks"/>.
141
197
This program is not meant to be run directly; it is really meant
188
244
assumed to separate the address from the port number.
191
This option is normally only useful for testing and
247
Normally, Zeroconf would be used to locate Mandos servers,
248
in which case this option would only be used when testing
198
255
<term><option>--interface=<replaceable
199
>NAME</replaceable></option></term>
256
>NAME</replaceable><arg rep='repeat'>,<replaceable
257
>NAME</replaceable></arg></option></term>
201
<replaceable>NAME</replaceable></option></term>
259
<replaceable>NAME</replaceable><arg rep='repeat'>,<replaceable
260
>NAME</replaceable></arg></option></term>
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
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.
210
If the <option>--connect</option> option is used, this
211
specifies the interface to use to connect to the address
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.
215
275
Note that since this program will normally run in the
216
276
initial RAM disk environment, the interface must be an
217
277
interface which exists at that stage. Thus, the interface
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
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"/>.
224
286
<replaceable>NAME</replaceable> can be the string
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
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.
371
509
server could be found and the password received from it could be
372
510
successfully decrypted and output on standard output. The
373
511
program will exit with a non-zero exit status only if a critical
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.
512
error occurs. Otherwise, it will forever connect to any
513
discovered <application>Mandos</application> servers, trying to
514
get a decryptable password and print it.
380
518
<refsect1 id="environment">
381
519
<title>ENVIRONMENT</title>
522
<term><envar>MANDOSPLUGINHELPERDIR</envar></term>
525
This environment variable will be assumed to contain the
526
directory containing any helper executables. The use and
527
nature of these helper executables, if any, is
528
purposefully not documented.
383
This program does not use any environment variables, not even
384
the ones provided by <citerefentry><refentrytitle
534
This program does not use any other environment variables, not
535
even the ones provided by <citerefentry><refentrytitle
385
536
>cryptsetup</refentrytitle><manvolnum>8</manvolnum>
541
<refsect1 id="network-hooks">
542
<title>NETWORK HOOKS</title>
544
If a network interface like a bridge or tunnel is required to
545
find a Mandos server, this requires the interface to be up and
546
running before <command>&COMMANDNAME;</command> starts looking
547
for Mandos servers. This can be accomplished by creating a
548
<quote>network hook</quote> program, and placing it in a special
552
Before the network is used (and again before program exit), any
553
runnable programs found in the network hook directory are run
554
with the argument <quote><literal>start</literal></quote> or
555
<quote><literal>stop</literal></quote>. This should bring up or
556
down, respectively, any network interface which
557
<command>&COMMANDNAME;</command> should use.
559
<refsect2 id="hook-requirements">
560
<title>REQUIREMENTS</title>
562
A network hook must be an executable file, and its name must
563
consist entirely of upper and lower case letters, digits,
564
underscores, periods, and hyphens.
567
A network hook will receive one argument, which can be one of
572
<term><literal>start</literal></term>
575
This should make the network hook create (if necessary)
576
and bring up a network interface.
581
<term><literal>stop</literal></term>
584
This should make the network hook take down a network
585
interface, and delete it if it did not exist previously.
590
<term><literal>files</literal></term>
593
This should make the network hook print, <emphasis>one
594
file per line</emphasis>, all the files needed for it to
595
run. (These files will be copied into the initial RAM
596
filesystem.) Typical use is for a network hook which is
597
a shell script to print its needed binaries.
600
It is not necessary to print any non-executable files
601
already in the network hook directory, these will be
602
copied implicitly if they otherwise satisfy the name
608
<term><literal>modules</literal></term>
611
This should make the network hook print, <emphasis>on
612
separate lines</emphasis>, all the kernel modules needed
613
for it to run. (These modules will be copied into the
614
initial RAM filesystem.) For instance, a tunnel
616
<quote><literal>tun</literal></quote> module.
622
The network hook will be provided with a number of environment
627
<term><envar>MANDOSNETHOOKDIR</envar></term>
630
The network hook directory, specified to
631
<command>&COMMANDNAME;</command> by the
632
<option>--network-hook-dir</option> option. Note: this
633
should <emphasis>always</emphasis> be used by the
634
network hook to refer to itself or any files in the hook
635
directory it may require.
640
<term><envar>DEVICE</envar></term>
643
The network interfaces, as specified to
644
<command>&COMMANDNAME;</command> by the
645
<option>--interface</option> option, combined to one
646
string and separated by commas. If this is set, and
647
does not contain the interface a hook will bring up,
648
there is no reason for a hook to continue.
653
<term><envar>MODE</envar></term>
656
This will be the same as the first argument;
657
i.e. <quote><literal>start</literal></quote>,
658
<quote><literal>stop</literal></quote>,
659
<quote><literal>files</literal></quote>, or
660
<quote><literal>modules</literal></quote>.
665
<term><envar>VERBOSITY</envar></term>
668
This will be the <quote><literal>1</literal></quote> if
669
the <option>--debug</option> option is passed to
670
<command>&COMMANDNAME;</command>, otherwise
671
<quote><literal>0</literal></quote>.
676
<term><envar>DELAY</envar></term>
679
This will be the same as the <option>--delay</option>
680
option passed to <command>&COMMANDNAME;</command>. Is
681
only set if <envar>MODE</envar> is
682
<quote><literal>start</literal></quote> or
683
<quote><literal>stop</literal></quote>.
688
<term><envar>CONNECT</envar></term>
691
This will be the same as the <option>--connect</option>
692
option passed to <command>&COMMANDNAME;</command>. Is
693
only set if <option>--connect</option> is passed and
694
<envar>MODE</envar> is
695
<quote><literal>start</literal></quote> or
696
<quote><literal>stop</literal></quote>.
702
A hook may not read from standard input, and should be
703
restrictive in printing to standard output or standard error
704
unless <varname>VERBOSITY</varname> is
705
<quote><literal>1</literal></quote>.
390
710
<refsect1 id="files">
391
711
<title>FILES</title>
493
837
The only remaining weak point is that someone with physical
494
838
access to the client hard drive might turn off the client
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
839
computer, read the OpenPGP and TLS keys directly from the hard
840
drive, and communicate with the server. To safeguard against
841
this, the server is supposed to notice the client disappearing
842
and stop giving out the encrypted data. Therefore, it is
843
important to set the timeout and checker interval values tightly
844
on the server. See <citerefentry><refentrytitle
501
845
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
504
848
It will also help if the checker program on the server is
505
849
configured to request something from the client which can not be
506
spoofed by someone else on the network, unlike unencrypted
507
<acronym>ICMP</acronym> echo (<quote>ping</quote>) replies.
850
spoofed by someone else on the network, like SSH server key
851
fingerprints, and unlike unencrypted <acronym>ICMP</acronym>
852
echo (<quote>ping</quote>) replies.
510
855
<emphasis>Note</emphasis>: This makes it completely insecure to