1
1
<?xml version="1.0" encoding="UTF-8"?>
2
2
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
3
3
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
4
<!ENTITY VERSION "1.0">
5
<!ENTITY COMMANDNAME "password-request">
6
<!ENTITY TIMESTAMP "2008-09-04">
4
<!ENTITY COMMANDNAME "mandos-client">
5
<!ENTITY TIMESTAMP "2015-07-06">
6
<!ENTITY % common SYSTEM "../common.ent">
9
10
<refentry xmlns:xi="http://www.w3.org/2001/XInclude">
11
12
<title>Mandos Manual</title>
12
<!-- Nwalsh’s docbook scripts use this to generate the footer: -->
13
<!-- NWalsh’s docbook scripts use this to generate the footer: -->
13
14
<productname>Mandos</productname>
14
<productnumber>&VERSION;</productnumber>
15
<productnumber>&version;</productnumber>
15
16
<date>&TIMESTAMP;</date>
18
19
<firstname>Björn</firstname>
19
20
<surname>Påhlsson</surname>
21
<email>belorn@fukt.bsnet.se</email>
22
<email>belorn@recompile.se</email>
25
26
<firstname>Teddy</firstname>
26
27
<surname>Hogeborn</surname>
28
<email>teddy@fukt.bsnet.se</email>
29
<email>teddy@recompile.se</email>
34
40
<holder>Teddy Hogeborn</holder>
35
41
<holder>Björn Påhlsson</holder>
37
43
<xi:include href="../legalnotice.xml"/>
41
47
<refentrytitle>&COMMANDNAME;</refentrytitle>
42
48
<manvolnum>8mandos</manvolnum>
115
136
</refsynopsisdiv>
117
138
<refsect1 id="description">
118
139
<title>DESCRIPTION</title>
120
141
<command>&COMMANDNAME;</command> is a client program that
121
142
communicates with <citerefentry><refentrytitle
122
143
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>
123
to get a password. It uses IPv6 link-local addresses to get
124
network connectivity, Zeroconf to find servers, and TLS with an
125
OpenPGP key to ensure authenticity and confidentiality. It
126
keeps running, trying all servers on the network, until it
127
receives a satisfactory reply or a TERM signal is received.
144
to get a password. In slightly more detail, this client program
145
brings up network interfaces, uses the interfaces’ IPv6
146
link-local addresses to get network connectivity, uses Zeroconf
147
to find servers on the local network, and communicates with
148
servers using TLS with an OpenPGP key to ensure authenticity and
149
confidentiality. This client program keeps running, trying all
150
servers on the network, until it receives a satisfactory reply
151
or a TERM signal. After all servers have been tried, all
152
servers are periodically retried. If no servers are found it
153
will wait indefinitely for new servers to appear.
156
The network interfaces are selected like this: If any interfaces
157
are specified using the <option>--interface</option> option,
158
those interface are used. Otherwise,
159
<command>&COMMANDNAME;</command> will use all interfaces that
160
are not loopback interfaces, are not point-to-point interfaces,
161
are capable of broadcasting and do not have the NOARP flag (see
162
<citerefentry><refentrytitle>netdevice</refentrytitle>
163
<manvolnum>7</manvolnum></citerefentry>). (If the
164
<option>--connect</option> option is used, point-to-point
165
interfaces and non-broadcast interfaces are accepted.) If any
166
used interfaces are not up and running, they are first taken up
167
(and later taken down again on program exit).
170
Before network interfaces are selected, all <quote>network
171
hooks</quote> are run; see <xref linkend="network-hooks"/>.
130
174
This program is not meant to be run directly; it is really meant
177
221
assumed to separate the address from the port number.
180
This option is normally only useful for testing and
224
Normally, Zeroconf would be used to locate Mandos servers,
225
in which case this option would only be used when testing
187
<term><option>--interface=
188
<replaceable>NAME</replaceable></option></term>
232
<term><option>--interface=<replaceable
233
>NAME</replaceable><arg rep='repeat'>,<replaceable
234
>NAME</replaceable></arg></option></term>
190
<replaceable>NAME</replaceable></option></term>
236
<replaceable>NAME</replaceable><arg rep='repeat'>,<replaceable
237
>NAME</replaceable></arg></option></term>
193
Network interface that will be brought up and scanned for
194
Mandos servers to connect to. The default it
195
<quote><literal>eth0</literal></quote>.
198
If the <option>--connect</option> option is used, this
199
specifies the interface to use to connect to the address
240
Comma separated list of network interfaces that will be
241
brought up and scanned for Mandos servers to connect to.
242
The default is the empty string, which will automatically
243
use all appropriate interfaces.
246
If the <option>--connect</option> option is used, and
247
exactly one interface name is specified (except
248
<quote><literal>none</literal></quote>), this specifies
249
the interface to use to connect to the address given.
252
Note that since this program will normally run in the
253
initial RAM disk environment, the interface must be an
254
interface which exists at that stage. Thus, the interface
255
can normally not be a pseudo-interface such as
256
<quote>br0</quote> or <quote>tun0</quote>; such interfaces
257
will not exist until much later in the boot process, and
258
can not be used by this program, unless created by a
259
<quote>network hook</quote> — see <xref
260
linkend="network-hooks"/>.
263
<replaceable>NAME</replaceable> can be the string
264
<quote><literal>none</literal></quote>; this will make
265
<command>&COMMANDNAME;</command> only bring up interfaces
266
specified <emphasis>before</emphasis> this string. This
267
is not recommended, and only meant for advanced users.
238
305
xpointer="priority"/>
243
310
<term><option>--dh-bits=<replaceable
244
311
>BITS</replaceable></option></term>
247
314
Sets the number of bits to use for the prime number in the
248
TLS Diffie-Hellman key exchange. Default is 1024.
315
TLS Diffie-Hellman key exchange. The default value is
316
selected automatically based on the OpenPGP key.
322
<term><option>--delay=<replaceable
323
>SECONDS</replaceable></option></term>
326
After bringing a network interface up, the program waits
327
for the interface to arrive in a <quote>running</quote>
328
state before proceeding. During this time, the kernel log
329
level will be lowered to reduce clutter on the system
330
console, alleviating any other plugins which might be
331
using the system console. This option sets the upper
332
limit of seconds to wait. The default is 2.5 seconds.
338
<term><option>--retry=<replaceable
339
>SECONDS</replaceable></option></term>
342
All Mandos servers are tried repeatedly until a password
343
is received. This value specifies, in seconds, how long
344
between each successive try <emphasis>for the same
345
server</emphasis>. The default is 10 seconds.
351
<term><option>--network-hook-dir=<replaceable
352
>DIR</replaceable></option></term>
355
Network hook directory. The default directory is
356
<quote><filename class="directory"
357
>/lib/mandos/network-hooks.d</filename></quote>.
325
438
server could be found and the password received from it could be
326
439
successfully decrypted and output on standard output. The
327
440
program will exit with a non-zero exit status only if a critical
328
error occurs. Otherwise, it will forever connect to new
329
<application>Mandos</application> servers as they appear, trying
330
to get a decryptable password.
441
error occurs. Otherwise, it will forever connect to any
442
discovered <application>Mandos</application> servers, trying to
443
get a decryptable password and print it.
334
447
<refsect1 id="environment">
335
448
<title>ENVIRONMENT</title>
451
<term><envar>MANDOSPLUGINHELPERDIR</envar></term>
454
This environment variable will be assumed to contain the
455
directory containing any helper executables. The use and
456
nature of these helper executables, if any, is
457
purposefully not documented.
337
This program does not use any environment variables, not even
338
the ones provided by <citerefentry><refentrytitle
463
This program does not use any other environment variables, not
464
even the ones provided by <citerefentry><refentrytitle
339
465
>cryptsetup</refentrytitle><manvolnum>8</manvolnum>
470
<refsect1 id="network-hooks">
471
<title>NETWORK HOOKS</title>
473
If a network interface like a bridge or tunnel is required to
474
find a Mandos server, this requires the interface to be up and
475
running before <command>&COMMANDNAME;</command> starts looking
476
for Mandos servers. This can be accomplished by creating a
477
<quote>network hook</quote> program, and placing it in a special
481
Before the network is used (and again before program exit), any
482
runnable programs found in the network hook directory are run
483
with the argument <quote><literal>start</literal></quote> or
484
<quote><literal>stop</literal></quote>. This should bring up or
485
down, respectively, any network interface which
486
<command>&COMMANDNAME;</command> should use.
488
<refsect2 id="hook-requirements">
489
<title>REQUIREMENTS</title>
491
A network hook must be an executable file, and its name must
492
consist entirely of upper and lower case letters, digits,
493
underscores, periods, and hyphens.
496
A network hook will receive one argument, which can be one of
501
<term><literal>start</literal></term>
504
This should make the network hook create (if necessary)
505
and bring up a network interface.
510
<term><literal>stop</literal></term>
513
This should make the network hook take down a network
514
interface, and delete it if it did not exist previously.
519
<term><literal>files</literal></term>
522
This should make the network hook print, <emphasis>one
523
file per line</emphasis>, all the files needed for it to
524
run. (These files will be copied into the initial RAM
525
filesystem.) Typical use is for a network hook which is
526
a shell script to print its needed binaries.
529
It is not necessary to print any non-executable files
530
already in the network hook directory, these will be
531
copied implicitly if they otherwise satisfy the name
537
<term><literal>modules</literal></term>
540
This should make the network hook print, <emphasis>on
541
separate lines</emphasis>, all the kernel modules needed
542
for it to run. (These modules will be copied into the
543
initial RAM filesystem.) For instance, a tunnel
545
<quote><literal>tun</literal></quote> module.
551
The network hook will be provided with a number of environment
556
<term><envar>MANDOSNETHOOKDIR</envar></term>
559
The network hook directory, specified to
560
<command>&COMMANDNAME;</command> by the
561
<option>--network-hook-dir</option> option. Note: this
562
should <emphasis>always</emphasis> be used by the
563
network hook to refer to itself or any files in the hook
564
directory it may require.
569
<term><envar>DEVICE</envar></term>
572
The network interfaces, as specified to
573
<command>&COMMANDNAME;</command> by the
574
<option>--interface</option> option, combined to one
575
string and separated by commas. If this is set, and
576
does not contain the interface a hook will bring up,
577
there is no reason for a hook to continue.
582
<term><envar>MODE</envar></term>
585
This will be the same as the first argument;
586
i.e. <quote><literal>start</literal></quote>,
587
<quote><literal>stop</literal></quote>,
588
<quote><literal>files</literal></quote>, or
589
<quote><literal>modules</literal></quote>.
594
<term><envar>VERBOSITY</envar></term>
597
This will be the <quote><literal>1</literal></quote> if
598
the <option>--debug</option> option is passed to
599
<command>&COMMANDNAME;</command>, otherwise
600
<quote><literal>0</literal></quote>.
605
<term><envar>DELAY</envar></term>
608
This will be the same as the <option>--delay</option>
609
option passed to <command>&COMMANDNAME;</command>. Is
610
only set if <envar>MODE</envar> is
611
<quote><literal>start</literal></quote> or
612
<quote><literal>stop</literal></quote>.
617
<term><envar>CONNECT</envar></term>
620
This will be the same as the <option>--connect</option>
621
option passed to <command>&COMMANDNAME;</command>. Is
622
only set if <option>--connect</option> is passed and
623
<envar>MODE</envar> is
624
<quote><literal>start</literal></quote> or
625
<quote><literal>stop</literal></quote>.
631
A hook may not read from standard input, and should be
632
restrictive in printing to standard output or standard error
633
unless <varname>VERBOSITY</varname> is
634
<quote><literal>1</literal></quote>.
639
<refsect1 id="files">
345
640
<title>FILES</title>
447
753
The only remaining weak point is that someone with physical
448
754
access to the client hard drive might turn off the client
449
755
computer, read the OpenPGP keys directly from the hard drive,
450
and communicate with the server. The defense against this is
451
that the server is supposed to notice the client disappearing
452
and will stop giving out the encrypted data. Therefore, it is
453
important to set the timeout and checker interval values tightly
454
on the server. See <citerefentry><refentrytitle
756
and communicate with the server. To safeguard against this, the
757
server is supposed to notice the client disappearing and stop
758
giving out the encrypted data. Therefore, it is important to
759
set the timeout and checker interval values tightly on the
760
server. See <citerefentry><refentrytitle
455
761
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
458
764
It will also help if the checker program on the server is
459
765
configured to request something from the client which can not be
460
spoofed by someone else on the network, unlike unencrypted
461
<acronym>ICMP</acronym> echo (<quote>ping</quote>) replies.
766
spoofed by someone else on the network, like SSH server key
767
fingerprints, and unlike unencrypted <acronym>ICMP</acronym>
768
echo (<quote>ping</quote>) replies.
464
771
<emphasis>Note</emphasis>: This makes it completely insecure to