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 COMMANDNAME "mandos-client">
5
<!ENTITY TIMESTAMP "2015-07-08">
6
<!ENTITY % common SYSTEM "../common.ent">
4
<!ENTITY VERSION "1.0">
5
<!ENTITY COMMANDNAME "password-request">
6
<!ENTITY TIMESTAMP "2008-09-03">
10
9
<refentry xmlns:xi="http://www.w3.org/2001/XInclude">
12
11
<title>Mandos Manual</title>
13
<!-- NWalsh’s docbook scripts use this to generate the footer: -->
12
<!-- Nwalsh’s docbook scripts use this to generate the footer: -->
14
13
<productname>Mandos</productname>
15
<productnumber>&version;</productnumber>
14
<productnumber>&VERSION;</productnumber>
16
15
<date>&TIMESTAMP;</date>
19
18
<firstname>Björn</firstname>
20
19
<surname>Påhlsson</surname>
22
<email>belorn@recompile.se</email>
21
<email>belorn@fukt.bsnet.se</email>
26
25
<firstname>Teddy</firstname>
27
26
<surname>Hogeborn</surname>
29
<email>teddy@recompile.se</email>
28
<email>teddy@fukt.bsnet.se</email>
40
34
<holder>Teddy Hogeborn</holder>
41
35
<holder>Björn Påhlsson</holder>
43
37
<xi:include href="../legalnotice.xml"/>
47
41
<refentrytitle>&COMMANDNAME;</refentrytitle>
48
42
<manvolnum>8mandos</manvolnum>
52
46
<refname><command>&COMMANDNAME;</command></refname>
54
Client for <application>Mandos</application>
60
54
<command>&COMMANDNAME;</command>
62
56
<arg choice="plain"><option>--connect
63
<replaceable>ADDRESS</replaceable><literal>:</literal
57
<replaceable>IPADDR</replaceable><literal>:</literal
64
58
><replaceable>PORT</replaceable></option></arg>
65
59
<arg choice="plain"><option>-c
66
<replaceable>ADDRESS</replaceable><literal>:</literal
60
<replaceable>IPADDR</replaceable><literal>:</literal
67
61
><replaceable>PORT</replaceable></option></arg>
65
<arg choice="plain"><option>--keydir
66
<replaceable>DIRECTORY</replaceable></option></arg>
67
<arg choice="plain"><option>-d
68
<replaceable>DIRECTORY</replaceable></option></arg>
71
72
<arg choice="plain"><option>--interface
72
<replaceable>NAME</replaceable><arg rep='repeat'
73
>,<replaceable>NAME</replaceable></arg></option></arg>
74
<arg choice="plain"><option>-i <replaceable>NAME</replaceable
75
><arg rep='repeat'>,<replaceable>NAME</replaceable></arg
73
<replaceable>NAME</replaceable></option></arg>
74
<arg choice="plain"><option>-i
75
<replaceable>NAME</replaceable></option></arg>
140
122
</refsynopsisdiv>
142
124
<refsect1 id="description">
143
125
<title>DESCRIPTION</title>
145
127
<command>&COMMANDNAME;</command> is a client program that
146
128
communicates with <citerefentry><refentrytitle
147
129
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>
148
to get a password. In slightly more detail, this client program
149
brings up network interfaces, uses the interfaces’ IPv6
150
link-local addresses to get network connectivity, uses Zeroconf
151
to find servers on the local network, and communicates with
152
servers using TLS with an OpenPGP key to ensure authenticity and
153
confidentiality. This client program keeps running, trying all
154
servers on the network, until it receives a satisfactory reply
155
or a TERM signal. After all servers have been tried, all
156
servers are periodically retried. If no servers are found it
157
will wait indefinitely for new servers to appear.
160
The network interfaces are selected like this: If any interfaces
161
are specified using the <option>--interface</option> option,
162
those interface are used. Otherwise,
163
<command>&COMMANDNAME;</command> will use all interfaces that
164
are not loopback interfaces, are not point-to-point interfaces,
165
are capable of broadcasting and do not have the NOARP flag (see
166
<citerefentry><refentrytitle>netdevice</refentrytitle>
167
<manvolnum>7</manvolnum></citerefentry>). (If the
168
<option>--connect</option> option is used, point-to-point
169
interfaces and non-broadcast interfaces are accepted.) If any
170
used interfaces are not up and running, they are first taken up
171
(and later taken down again on program exit).
174
Before network interfaces are selected, all <quote>network
175
hooks</quote> are run; see <xref linkend="network-hooks"/>.
130
to get a password. It uses IPv6 link-local addresses to get
131
network connectivity, Zeroconf to find servers, and TLS with an
132
OpenPGP key to ensure authenticity and confidentiality. It
133
keeps running, trying all servers on the network, until it
134
receives a satisfactory reply or a TERM signal is recieved.
178
137
This program is not meant to be run directly; it is really meant
225
184
assumed to separate the address from the port number.
228
Normally, Zeroconf would be used to locate Mandos servers,
229
in which case this option would only be used when testing
187
This option is normally only useful for testing and
236
<term><option>--interface=<replaceable
237
>NAME</replaceable><arg rep='repeat'>,<replaceable
238
>NAME</replaceable></arg></option></term>
194
<term><option>--keydir=<replaceable
195
>DIRECTORY</replaceable></option></term>
197
<replaceable>DIRECTORY</replaceable></option></term>
200
Directory to read the OpenPGP key files
201
<filename>pubkey.txt</filename> and
202
<filename>seckey.txt</filename> from. The default is
203
<filename>/conf/conf.d/mandos</filename> (in the initial
204
<acronym>RAM</acronym> disk environment).
210
<term><option>--interface=
211
<replaceable>NAME</replaceable></option></term>
240
<replaceable>NAME</replaceable><arg rep='repeat'>,<replaceable
241
>NAME</replaceable></arg></option></term>
213
<replaceable>NAME</replaceable></option></term>
244
Comma separated list of network interfaces that will be
245
brought up and scanned for Mandos servers to connect to.
246
The default is the empty string, which will automatically
247
use all appropriate interfaces.
250
If the <option>--connect</option> option is used, and
251
exactly one interface name is specified (except
252
<quote><literal>none</literal></quote>), this specifies
253
the interface to use to connect to the address given.
256
Note that since this program will normally run in the
257
initial RAM disk environment, the interface must be an
258
interface which exists at that stage. Thus, the interface
259
can normally not be a pseudo-interface such as
260
<quote>br0</quote> or <quote>tun0</quote>; such interfaces
261
will not exist until much later in the boot process, and
262
can not be used by this program, unless created by a
263
<quote>network hook</quote> — see <xref
264
linkend="network-hooks"/>.
267
<replaceable>NAME</replaceable> can be the string
268
<quote><literal>none</literal></quote>; this will make
269
<command>&COMMANDNAME;</command> only bring up interfaces
270
specified <emphasis>before</emphasis> this string. This
271
is not recommended, and only meant for advanced users.
216
Network interface that will be brought up and scanned for
217
Mandos servers to connect to. The default it
218
<quote><literal>eth0</literal></quote>.
221
If the <option>--connect</option> option is used, this
222
specifies the interface to use to connect to the address
309
263
xpointer="priority"/>
314
268
<term><option>--dh-bits=<replaceable
315
269
>BITS</replaceable></option></term>
318
272
Sets the number of bits to use for the prime number in the
319
TLS Diffie-Hellman key exchange. The default value is
320
selected automatically based on the OpenPGP key. Note
321
that if the <option>--dh-params</option> option is used,
322
the values from that file will be used instead.
328
<term><option>--dh-params=<replaceable
329
>FILE</replaceable></option></term>
332
Specifies a PEM-encoded PKCS#3 file to read the parameters
333
needed by the TLS Diffie-Hellman key exchange from. If
334
this option is not given, or if the file for some reason
335
could not be used, the parameters will be generated on
336
startup, which will take some time and processing power.
337
Those using servers running under time, power or processor
338
constraints may want to generate such a file in advance
345
<term><option>--delay=<replaceable
346
>SECONDS</replaceable></option></term>
349
After bringing a network interface up, the program waits
350
for the interface to arrive in a <quote>running</quote>
351
state before proceeding. During this time, the kernel log
352
level will be lowered to reduce clutter on the system
353
console, alleviating any other plugins which might be
354
using the system console. This option sets the upper
355
limit of seconds to wait. The default is 2.5 seconds.
361
<term><option>--retry=<replaceable
362
>SECONDS</replaceable></option></term>
365
All Mandos servers are tried repeatedly until a password
366
is received. This value specifies, in seconds, how long
367
between each successive try <emphasis>for the same
368
server</emphasis>. The default is 10 seconds.
374
<term><option>--network-hook-dir=<replaceable
375
>DIR</replaceable></option></term>
378
Network hook directory. The default directory is
379
<quote><filename class="directory"
380
>/lib/mandos/network-hooks.d</filename></quote>.
273
TLS Diffie-Hellman key exchange. Default is 1024.
461
350
server could be found and the password received from it could be
462
351
successfully decrypted and output on standard output. The
463
352
program will exit with a non-zero exit status only if a critical
464
error occurs. Otherwise, it will forever connect to any
465
discovered <application>Mandos</application> servers, trying to
466
get a decryptable password and print it.
353
error occurs. Otherwise, it will forever connect to new
354
<application>Mandos</application> servers as they appear, trying
355
to get a decryptable password.
470
359
<refsect1 id="environment">
471
360
<title>ENVIRONMENT</title>
474
<term><envar>MANDOSPLUGINHELPERDIR</envar></term>
477
This environment variable will be assumed to contain the
478
directory containing any helper executables. The use and
479
nature of these helper executables, if any, is
480
purposefully not documented.
486
This program does not use any other environment variables, not
487
even the ones provided by <citerefentry><refentrytitle
362
This program does not use any environment variables, not even
363
the ones provided by <citerefentry><refentrytitle
488
364
>cryptsetup</refentrytitle><manvolnum>8</manvolnum>
493
<refsect1 id="network-hooks">
494
<title>NETWORK HOOKS</title>
496
If a network interface like a bridge or tunnel is required to
497
find a Mandos server, this requires the interface to be up and
498
running before <command>&COMMANDNAME;</command> starts looking
499
for Mandos servers. This can be accomplished by creating a
500
<quote>network hook</quote> program, and placing it in a special
504
Before the network is used (and again before program exit), any
505
runnable programs found in the network hook directory are run
506
with the argument <quote><literal>start</literal></quote> or
507
<quote><literal>stop</literal></quote>. This should bring up or
508
down, respectively, any network interface which
509
<command>&COMMANDNAME;</command> should use.
511
<refsect2 id="hook-requirements">
512
<title>REQUIREMENTS</title>
514
A network hook must be an executable file, and its name must
515
consist entirely of upper and lower case letters, digits,
516
underscores, periods, and hyphens.
519
A network hook will receive one argument, which can be one of
524
<term><literal>start</literal></term>
527
This should make the network hook create (if necessary)
528
and bring up a network interface.
533
<term><literal>stop</literal></term>
536
This should make the network hook take down a network
537
interface, and delete it if it did not exist previously.
542
<term><literal>files</literal></term>
545
This should make the network hook print, <emphasis>one
546
file per line</emphasis>, all the files needed for it to
547
run. (These files will be copied into the initial RAM
548
filesystem.) Typical use is for a network hook which is
549
a shell script to print its needed binaries.
552
It is not necessary to print any non-executable files
553
already in the network hook directory, these will be
554
copied implicitly if they otherwise satisfy the name
560
<term><literal>modules</literal></term>
563
This should make the network hook print, <emphasis>on
564
separate lines</emphasis>, all the kernel modules needed
565
for it to run. (These modules will be copied into the
566
initial RAM filesystem.) For instance, a tunnel
568
<quote><literal>tun</literal></quote> module.
574
The network hook will be provided with a number of environment
579
<term><envar>MANDOSNETHOOKDIR</envar></term>
582
The network hook directory, specified to
583
<command>&COMMANDNAME;</command> by the
584
<option>--network-hook-dir</option> option. Note: this
585
should <emphasis>always</emphasis> be used by the
586
network hook to refer to itself or any files in the hook
587
directory it may require.
592
<term><envar>DEVICE</envar></term>
595
The network interfaces, as specified to
596
<command>&COMMANDNAME;</command> by the
597
<option>--interface</option> option, combined to one
598
string and separated by commas. If this is set, and
599
does not contain the interface a hook will bring up,
600
there is no reason for a hook to continue.
605
<term><envar>MODE</envar></term>
608
This will be the same as the first argument;
609
i.e. <quote><literal>start</literal></quote>,
610
<quote><literal>stop</literal></quote>,
611
<quote><literal>files</literal></quote>, or
612
<quote><literal>modules</literal></quote>.
617
<term><envar>VERBOSITY</envar></term>
620
This will be the <quote><literal>1</literal></quote> if
621
the <option>--debug</option> option is passed to
622
<command>&COMMANDNAME;</command>, otherwise
623
<quote><literal>0</literal></quote>.
628
<term><envar>DELAY</envar></term>
631
This will be the same as the <option>--delay</option>
632
option passed to <command>&COMMANDNAME;</command>. Is
633
only set if <envar>MODE</envar> is
634
<quote><literal>start</literal></quote> or
635
<quote><literal>stop</literal></quote>.
640
<term><envar>CONNECT</envar></term>
643
This will be the same as the <option>--connect</option>
644
option passed to <command>&COMMANDNAME;</command>. Is
645
only set if <option>--connect</option> is passed and
646
<envar>MODE</envar> is
647
<quote><literal>start</literal></quote> or
648
<quote><literal>stop</literal></quote>.
654
A hook may not read from standard input, and should be
655
restrictive in printing to standard output or standard error
656
unless <varname>VERBOSITY</varname> is
657
<quote><literal>1</literal></quote>.
662
<refsect1 id="files">
663
370
<title>FILES</title>
725
420
</informalexample>
726
421
<informalexample>
728
Run in debug mode, and use a custom key:
423
Run in debug mode, and use a custom key directory:
732
<!-- do not wrap this line -->
733
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt</userinput>
426
<!-- do not wrap this line -->
427
<userinput>&COMMANDNAME; --debug --keydir keydir</userinput>
736
429
</informalexample>
737
430
<informalexample>
739
Run in debug mode, with a custom key, and do not use Zeroconf
740
to locate a server; connect directly to the IPv6 link-local
432
Run in debug mode, with a custom key directory, and do not use
433
Zeroconf to locate a server; connect directly to the IPv6
741
434
address <quote><systemitem class="ipaddress"
742
>fe80::aede:48ff:fe71:f6f2</systemitem></quote>, port 4711,
743
using interface eth2:
435
>2001:db8:f983:bd0b:30de:ae4a:71f2:f672</systemitem></quote>,
436
port 4711, using interface eth2:
747
440
<!-- do not wrap this line -->
748
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt --connect fe80::aede:48ff:fe71:f6f2:4711 --interface eth2</userinput>
441
<userinput>&COMMANDNAME; --debug --keydir keydir --connect 2001:db8:f983:bd0b:30de:ae4a:71f2:f672:4711 --interface eth2</userinput>
751
444
</informalexample>
754
447
<refsect1 id="security">
755
448
<title>SECURITY</title>
776
469
The only remaining weak point is that someone with physical
777
470
access to the client hard drive might turn off the client
778
471
computer, read the OpenPGP keys directly from the hard drive,
779
and communicate with the server. To safeguard against this, the
780
server is supposed to notice the client disappearing and stop
781
giving out the encrypted data. Therefore, it is important to
782
set the timeout and checker interval values tightly on the
783
server. See <citerefentry><refentrytitle
472
and communicate with the server. The defense against this is
473
that the server is supposed to notice the client disappearing
474
and will stop giving out the encrypted data. Therefore, it is
475
important to set the timeout and checker interval values tightly
476
on the server. See <citerefentry><refentrytitle
784
477
>mandos</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
787
480
It will also help if the checker program on the server is
788
481
configured to request something from the client which can not be
789
spoofed by someone else on the network, like SSH server key
790
fingerprints, and unlike unencrypted <acronym>ICMP</acronym>
791
echo (<quote>ping</quote>) replies.
482
spoofed by someone else on the network, unlike unencrypted
483
<acronym>ICMP</acronym> echo (<quote>ping</quote>) replies.
794
486
<emphasis>Note</emphasis>: This makes it completely insecure to