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  • Committer: Teddy Hogeborn
  • Date: 2015-07-02 18:22:22 UTC
  • mto: (237.7.307 trunk)
  • mto: This revision was merged to the branch mainline in revision 325.
  • Revision ID: teddy@recompile.se-20150702182222-034v03mb8orwhezn
mandos-client: Minor changes to check for more error conditions.

* mandos-client.c (add_remove_local_route): Do TEMP_FAILURE_RETRY
                                            around closing of
                                            /dev/null.  Check return
                                            value when opening helper
                                            directory and helper
                                            executable.
  (run_network_hooks): Cast return value of TEMP_FAILURE_RETRY to int.
                       Do TEMP_FAILURE_RETRY around closing of
                       /dev/null.

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plugins.d/mandos-client.xml
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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        "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
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<!ENTITY COMMANDNAME "mandos-client">
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<!ENTITY TIMESTAMP "2008-09-30">
 
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<!ENTITY TIMESTAMP "2015-06-29">
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<!ENTITY % common SYSTEM "../common.ent">
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%common;
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]>
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        <firstname>Björn</firstname>
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        <surname>Påhlsson</surname>
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        <address>
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          <email>belorn@fukt.bsnet.se</email>
 
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          <email>belorn@recompile.se</email>
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        </address>
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      </author>
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      <author>
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        <firstname>Teddy</firstname>
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        <surname>Hogeborn</surname>
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        <address>
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          <email>teddy@fukt.bsnet.se</email>
 
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          <email>teddy@recompile.se</email>
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        </address>
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      </author>
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    </authorgroup>
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    <copyright>
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      <year>2008</year>
 
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      <year>2009</year>
 
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      <year>2012</year>
 
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      <year>2013</year>
 
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      <year>2014</year>
 
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      <year>2015</year>
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      <holder>Teddy Hogeborn</holder>
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      <holder>Björn Påhlsson</holder>
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    </copyright>
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        ><replaceable>PORT</replaceable></option></arg>
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      </group>
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      <sbr/>
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      <group>
 
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      <group rep='repeat'>
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        <arg choice="plain"><option>--interface
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        <replaceable>NAME</replaceable></option></arg>
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        <arg choice="plain"><option>-i
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        <replaceable>NAME</replaceable></option></arg>
 
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        <replaceable>NAME</replaceable><arg rep='repeat'
 
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        >,<replaceable>NAME</replaceable></arg></option></arg>
 
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        <arg choice="plain"><option>-i <replaceable>NAME</replaceable
 
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        ><arg rep='repeat'>,<replaceable>NAME</replaceable></arg
 
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        ></option></arg>
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      </group>
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      <sbr/>
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      <group>
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      </arg>
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      <sbr/>
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      <arg>
 
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        <option>--delay <replaceable>SECONDS</replaceable></option>
 
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      </arg>
 
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      <sbr/>
 
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      <arg>
 
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        <option>--retry <replaceable>SECONDS</replaceable></option>
 
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      </arg>
 
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      <sbr/>
 
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      <arg>
 
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        <option>--network-hook-dir
 
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        <replaceable>DIR</replaceable></option>
 
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      </arg>
 
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      <sbr/>
 
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      <arg>
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        <option>--debug</option>
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      </arg>
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    </cmdsynopsis>
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      <command>&COMMANDNAME;</command> is a client program that
122
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      communicates with <citerefentry><refentrytitle
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      >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
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      keeps running, trying all servers on the network, until it
128
 
      receives a satisfactory reply or a TERM signal is received.
 
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      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.
 
154
    </para>
 
155
    <para>
 
156
      The network interfaces are selected like this: If any interfaces
 
157
      are specified using the <option>--interface</option> option,
 
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      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).
 
168
    </para>
 
169
    <para>
 
170
      Before network interfaces are selected, all <quote>network
 
171
      hooks</quote> are run; see <xref linkend="network-hooks"/>.
129
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    </para>
130
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    <para>
131
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      This program is not meant to be run directly; it is really meant
178
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            assumed to separate the address from the port number.
179
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          </para>
180
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          <para>
181
 
            This option is normally only useful for testing and
182
 
            debugging.
 
224
            Normally, Zeroconf would be used to locate Mandos servers,
 
225
            in which case this option would only be used when testing
 
226
            and debugging.
183
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          </para>
184
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        </listitem>
185
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      </varlistentry>
186
230
      
187
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      <varlistentry>
188
 
        <term><option>--interface=
189
 
        <replaceable>NAME</replaceable></option></term>
 
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        <term><option>--interface=<replaceable
 
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        >NAME</replaceable><arg rep='repeat'>,<replaceable
 
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        >NAME</replaceable></arg></option></term>
190
235
        <term><option>-i
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        <replaceable>NAME</replaceable></option></term>
 
236
        <replaceable>NAME</replaceable><arg rep='repeat'>,<replaceable
 
237
        >NAME</replaceable></arg></option></term>
192
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        <listitem>
193
239
          <para>
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>.
197
 
          </para>
198
 
          <para>
199
 
            If the <option>--connect</option> option is used, this
200
 
            specifies the interface to use to connect to the address
201
 
            given.
 
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
 
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            use all appropriate interfaces.
 
244
          </para>
 
245
          <para>
 
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.
 
250
          </para>
 
251
          <para>
 
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
 
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            <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"/>.
 
261
          </para>
 
262
          <para>
 
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.
202
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          </para>
203
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        </listitem>
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      </varlistentry>
250
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          </para>
251
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        </listitem>
252
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      </varlistentry>
 
319
 
 
320
      <varlistentry>
 
321
        <term><option>--delay=<replaceable
 
322
        >SECONDS</replaceable></option></term>
 
323
        <listitem>
 
324
          <para>
 
325
            After bringing a network interface up, the program waits
 
326
            for the interface to arrive in a <quote>running</quote>
 
327
            state before proceeding.  During this time, the kernel log
 
328
            level will be lowered to reduce clutter on the system
 
329
            console, alleviating any other plugins which might be
 
330
            using the system console.  This option sets the upper
 
331
            limit of seconds to wait.  The default is 2.5 seconds.
 
332
          </para>
 
333
        </listitem>
 
334
      </varlistentry>
 
335
 
 
336
      <varlistentry>
 
337
        <term><option>--retry=<replaceable
 
338
        >SECONDS</replaceable></option></term>
 
339
        <listitem>
 
340
          <para>
 
341
            All Mandos servers are tried repeatedly until a password
 
342
            is received.  This value specifies, in seconds, how long
 
343
            between each successive try <emphasis>for the same
 
344
            server</emphasis>.  The default is 10 seconds.
 
345
          </para>
 
346
        </listitem>
 
347
      </varlistentry>
 
348
 
 
349
      <varlistentry>
 
350
        <term><option>--network-hook-dir=<replaceable
 
351
        >DIR</replaceable></option></term>
 
352
        <listitem>
 
353
          <para>
 
354
            Network hook directory.  The default directory is
 
355
            <quote><filename class="directory"
 
356
            >/lib/mandos/network-hooks.d</filename></quote>.
 
357
          </para>
 
358
        </listitem>
 
359
      </varlistentry>
253
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254
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      <varlistentry>
255
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        <term><option>--debug</option></term>
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      <refentrytitle>plugin-runner</refentrytitle>
317
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      <manvolnum>8mandos</manvolnum></citerefentry>) is used to run
318
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      both this program and others in in parallel,
319
 
      <emphasis>one</emphasis> of which will prompt for passwords on
320
 
      the system console.
 
426
      <emphasis>one</emphasis> of which (<citerefentry>
 
427
      <refentrytitle>password-prompt</refentrytitle>
 
428
      <manvolnum>8mandos</manvolnum></citerefentry>) will prompt for
 
429
      passwords on the system console.
321
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    </para>
322
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  </refsect1>
323
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      server could be found and the password received from it could be
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      successfully decrypted and output on standard output.  The
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      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.
 
440
      error occurs.  Otherwise, it will forever connect to any
 
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      discovered <application>Mandos</application> servers, trying to
 
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      get a decryptable password and print it.
334
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    </para>
335
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  </refsect1>
336
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337
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  <refsect1 id="environment">
338
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    <title>ENVIRONMENT</title>
 
448
    <variablelist>
 
449
      <varlistentry>
 
450
        <term><envar>MANDOSPLUGINHELPERDIR</envar></term>
 
451
        <listitem>
 
452
          <para>
 
453
            This environment variable will be assumed to contain the
 
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            directory containing any helper executables.  The use and
 
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            nature of these helper executables, if any, is
 
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            purposefully not documented.
 
457
        </para>
 
458
        </listitem>
 
459
      </varlistentry>
 
460
    </variablelist>
339
461
    <para>
340
 
      This program does not use any environment variables, not even
341
 
      the ones provided by <citerefentry><refentrytitle
 
462
      This program does not use any other environment variables, not
 
463
      even the ones provided by <citerefentry><refentrytitle
342
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      >cryptsetup</refentrytitle><manvolnum>8</manvolnum>
343
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    </citerefentry>.
344
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    </para>
345
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  </refsect1>
346
468
  
347
 
  <refsect1 id="file">
 
469
  <refsect1 id="network-hooks">
 
470
    <title>NETWORK HOOKS</title>
 
471
    <para>
 
472
      If a network interface like a bridge or tunnel is required to
 
473
      find a Mandos server, this requires the interface to be up and
 
474
      running before <command>&COMMANDNAME;</command> starts looking
 
475
      for Mandos servers.  This can be accomplished by creating a
 
476
      <quote>network hook</quote> program, and placing it in a special
 
477
      directory.
 
478
    </para>
 
479
    <para>
 
480
      Before the network is used (and again before program exit), any
 
481
      runnable programs found in the network hook directory are run
 
482
      with the argument <quote><literal>start</literal></quote> or
 
483
      <quote><literal>stop</literal></quote>.  This should bring up or
 
484
      down, respectively, any network interface which
 
485
      <command>&COMMANDNAME;</command> should use.
 
486
    </para>
 
487
    <refsect2 id="hook-requirements">
 
488
      <title>REQUIREMENTS</title>
 
489
      <para>
 
490
        A network hook must be an executable file, and its name must
 
491
        consist entirely of upper and lower case letters, digits,
 
492
        underscores, periods, and hyphens.
 
493
      </para>
 
494
      <para>
 
495
        A network hook will receive one argument, which can be one of
 
496
        the following:
 
497
      </para>
 
498
      <variablelist>
 
499
        <varlistentry>
 
500
          <term><literal>start</literal></term>
 
501
          <listitem>
 
502
            <para>
 
503
              This should make the network hook create (if necessary)
 
504
              and bring up a network interface.
 
505
            </para>
 
506
          </listitem>
 
507
        </varlistentry>
 
508
        <varlistentry>
 
509
          <term><literal>stop</literal></term>
 
510
          <listitem>
 
511
            <para>
 
512
              This should make the network hook take down a network
 
513
              interface, and delete it if it did not exist previously.
 
514
            </para>
 
515
          </listitem>
 
516
        </varlistentry>
 
517
        <varlistentry>
 
518
          <term><literal>files</literal></term>
 
519
          <listitem>
 
520
            <para>
 
521
              This should make the network hook print, <emphasis>one
 
522
              file per line</emphasis>, all the files needed for it to
 
523
              run.  (These files will be copied into the initial RAM
 
524
              filesystem.)  Typical use is for a network hook which is
 
525
              a shell script to print its needed binaries.
 
526
            </para>
 
527
            <para>
 
528
              It is not necessary to print any non-executable files
 
529
              already in the network hook directory, these will be
 
530
              copied implicitly if they otherwise satisfy the name
 
531
              requirements.
 
532
            </para>
 
533
          </listitem>
 
534
        </varlistentry>
 
535
        <varlistentry>
 
536
          <term><literal>modules</literal></term>
 
537
          <listitem>
 
538
            <para>
 
539
              This should make the network hook print, <emphasis>on
 
540
              separate lines</emphasis>, all the kernel modules needed
 
541
              for it to run.  (These modules will be copied into the
 
542
              initial RAM filesystem.)  For instance, a tunnel
 
543
              interface needs the
 
544
              <quote><literal>tun</literal></quote> module.
 
545
            </para>
 
546
          </listitem>
 
547
        </varlistentry>
 
548
      </variablelist>
 
549
      <para>
 
550
        The network hook will be provided with a number of environment
 
551
        variables:
 
552
      </para>
 
553
      <variablelist>
 
554
        <varlistentry>
 
555
          <term><envar>MANDOSNETHOOKDIR</envar></term>
 
556
          <listitem>
 
557
            <para>
 
558
              The network hook directory, specified to
 
559
              <command>&COMMANDNAME;</command> by the
 
560
              <option>--network-hook-dir</option> option.  Note: this
 
561
              should <emphasis>always</emphasis> be used by the
 
562
              network hook to refer to itself or any files in the hook
 
563
              directory it may require.
 
564
            </para>
 
565
          </listitem>
 
566
        </varlistentry>
 
567
        <varlistentry>
 
568
          <term><envar>DEVICE</envar></term>
 
569
          <listitem>
 
570
            <para>
 
571
              The network interfaces, as specified to
 
572
              <command>&COMMANDNAME;</command> by the
 
573
              <option>--interface</option> option, combined to one
 
574
              string and separated by commas.  If this is set, and
 
575
              does not contain the interface a hook will bring up,
 
576
              there is no reason for a hook to continue.
 
577
            </para>
 
578
          </listitem>
 
579
        </varlistentry>
 
580
        <varlistentry>
 
581
          <term><envar>MODE</envar></term>
 
582
          <listitem>
 
583
            <para>
 
584
              This will be the same as the first argument;
 
585
              i.e. <quote><literal>start</literal></quote>,
 
586
              <quote><literal>stop</literal></quote>,
 
587
              <quote><literal>files</literal></quote>, or
 
588
              <quote><literal>modules</literal></quote>.
 
589
            </para>
 
590
          </listitem>
 
591
        </varlistentry>
 
592
        <varlistentry>
 
593
          <term><envar>VERBOSITY</envar></term>
 
594
          <listitem>
 
595
            <para>
 
596
              This will be the <quote><literal>1</literal></quote> if
 
597
              the <option>--debug</option> option is passed to
 
598
              <command>&COMMANDNAME;</command>, otherwise
 
599
              <quote><literal>0</literal></quote>.
 
600
            </para>
 
601
          </listitem>
 
602
        </varlistentry>
 
603
        <varlistentry>
 
604
          <term><envar>DELAY</envar></term>
 
605
          <listitem>
 
606
            <para>
 
607
              This will be the same as the <option>--delay</option>
 
608
              option passed to <command>&COMMANDNAME;</command>.  Is
 
609
              only set if <envar>MODE</envar> is
 
610
              <quote><literal>start</literal></quote> or
 
611
              <quote><literal>stop</literal></quote>.
 
612
            </para>
 
613
          </listitem>
 
614
        </varlistentry>
 
615
        <varlistentry>
 
616
          <term><envar>CONNECT</envar></term>
 
617
          <listitem>
 
618
            <para>
 
619
              This will be the same as the <option>--connect</option>
 
620
              option passed to <command>&COMMANDNAME;</command>.  Is
 
621
              only set if <option>--connect</option> is passed and
 
622
              <envar>MODE</envar> is
 
623
              <quote><literal>start</literal></quote> or
 
624
              <quote><literal>stop</literal></quote>.
 
625
            </para>
 
626
          </listitem>
 
627
        </varlistentry>
 
628
      </variablelist>
 
629
      <para>
 
630
        A hook may not read from standard input, and should be
 
631
        restrictive in printing to standard output or standard error
 
632
        unless <varname>VERBOSITY</varname> is
 
633
        <quote><literal>1</literal></quote>.
 
634
      </para>
 
635
    </refsect2>
 
636
  </refsect1>
 
637
  
 
638
  <refsect1 id="files">
348
639
    <title>FILES</title>
349
640
    <variablelist>
350
641
      <varlistentry>
361
652
          </para>
362
653
        </listitem>
363
654
      </varlistentry>
 
655
      <varlistentry>
 
656
        <term><filename
 
657
        class="directory">/lib/mandos/network-hooks.d</filename></term>
 
658
        <listitem>
 
659
          <para>
 
660
            Directory where network hooks are located.  Change this
 
661
            with the <option>--network-hook-dir</option> option.  See
 
662
            <xref linkend="network-hooks"/>.
 
663
          </para>
 
664
        </listitem>
 
665
      </varlistentry>
364
666
    </variablelist>
365
667
  </refsect1>
366
668
  
380
682
    </para>
381
683
    <informalexample>
382
684
      <para>
383
 
        Normal invocation needs no options, if the network interface
384
 
        is <quote>eth0</quote>:
 
685
        Normal invocation needs no options, if the network interfaces
 
686
        can be automatically determined:
385
687
      </para>
386
688
      <para>
387
689
        <userinput>&COMMANDNAME;</userinput>
389
691
    </informalexample>
390
692
    <informalexample>
391
693
      <para>
392
 
        Search for Mandos servers (and connect to them) using another
393
 
        interface:
 
694
        Search for Mandos servers (and connect to them) using one
 
695
        specific interface:
394
696
      </para>
395
697
      <para>
396
698
        <!-- do not wrap this line -->
411
713
    <informalexample>
412
714
      <para>
413
715
        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:
 
716
        to locate a server; connect directly to the IPv6 link-local
 
717
        address <quote><systemitem class="ipaddress"
 
718
        >fe80::aede:48ff:fe71:f6f2</systemitem></quote>, port 4711,
 
719
        using interface eth2:
418
720
      </para>
419
721
      <para>
420
722
 
421
723
<!-- 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>
 
724
<userinput>&COMMANDNAME; --debug --pubkey keydir/pubkey.txt --seckey keydir/seckey.txt --connect fe80::aede:48ff:fe71:f6f2:4711 --interface eth2</userinput>
423
725
 
424
726
      </para>
425
727
    </informalexample>
460
762
    <para>
461
763
      It will also help if the checker program on the server is
462
764
      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.
 
765
      spoofed by someone else on the network, like SSH server key
 
766
      fingerprints, and unlike unencrypted <acronym>ICMP</acronym>
 
767
      echo (<quote>ping</quote>) replies.
465
768
    </para>
466
769
    <para>
467
770
      <emphasis>Note</emphasis>: This makes it completely insecure to
475
778
  <refsect1 id="see_also">
476
779
    <title>SEE ALSO</title>
477
780
    <para>
 
781
      <citerefentry><refentrytitle>intro</refentrytitle>
 
782
      <manvolnum>8mandos</manvolnum></citerefentry>,
478
783
      <citerefentry><refentrytitle>cryptsetup</refentrytitle>
479
784
      <manvolnum>8</manvolnum></citerefentry>,
480
785
      <citerefentry><refentrytitle>crypttab</refentrytitle>
558
863
              <para>
559
864
                This client uses IPv6 link-local addresses, which are
560
865
                immediately usable since a link-local addresses is
561
 
                automatically assigned to a network interfaces when it
 
866
                automatically assigned to a network interface when it
562
867
                is brought up.
563
868
              </para>
564
869
            </listitem>