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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
"http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd">
<article>
<!--$Id$-->
<articleinfo>
<title>Operating Shorewall and Shorewall Lite</title>
<authorgroup>
<author>
<firstname>Tom</firstname>
<surname>Eastep</surname>
</author>
</authorgroup>
<pubdate><?dbtimestamp format="Y/m/d"?></pubdate>
<copyright>
<year>2004</year>
<year>2005</year>
<year>2006</year>
<year>2007</year>
<holder>Thomas M. Eastep</holder>
</copyright>
<legalnotice>
<para>Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License, Version
1.2 or any later version published by the Free Software Foundation; with
no Invariant Sections, with no Front-Cover, and with no Back-Cover
Texts. A copy of the license is included in the section entitled
<quote><ulink url="GnuCopyright.htm">GNU Free Documentation
License</ulink></quote>.</para>
</legalnotice>
</articleinfo>
<caution>
<para><emphasis role="bold">This article applies to Shorewall 4.3 and
later. If you are running a version of Shorewall earlier than Shorewall
4.3.5 then please see the documentation for that
release</emphasis>.</para>
</caution>
<section id="CLI">
<title>/sbin/shorewall and /sbin/shorewall-lite</title>
<para><filename>/sbin/shorewall</filename> is the program that you use to
interact with Shorewall. Normally the root user's PATH includes
<filename>/sbin</filename> and the program can be run from a shell prompt
by simply typing <command>shorewall</command> followed by a
command.</para>
<warning>
<para>In some releases of KDE, the default configuration of the
<emphasis role="bold">konsole</emphasis> program is brain dead with
respect to the "Root Console". It executes the command "su" where it
should execute "su -"; the latter will cause a login shell to be created
which will in turn set PATH properly. You can correct this problem as
follows:</para>
<orderedlist>
<listitem>
<para>Click on "Settings" on the toolbar and select "Configure
Konsole"</para>
</listitem>
<listitem>
<para>Select the "Session" tab.</para>
</listitem>
<listitem>
<para>Click on "Root Console"</para>
</listitem>
<listitem>
<para>Change the Execute command from "su" to "su -"</para>
</listitem>
<listitem>
<para>Click on "Save Session"</para>
</listitem>
<listitem>
<para>Click on "Ok"</para>
</listitem>
</orderedlist>
</warning>
<para>To see a list of supported commands, use the <command>help</command>
command:</para>
<programlisting><command>shorewall help</command></programlisting>
<para>To get further information about a particular command, use the
<command>man</command> command:</para>
<programlisting><command>man shorewall</command>
</programlisting>
<para>The program <emphasis role="bold">/sbin/shorewall-lite</emphasis>
performs a similar role with Shorewall-lite.</para>
<para>For a more complete description of the files and directories
involved in Shorewall and Shorewall-lite, see the <ulink
url="Anatomy.html">Shorewall Anatomy article</ulink>.</para>
</section>
<section id="Starting">
<title>Starting, Stopping and Clearing</title>
<para>As explained in the <ulink
url="Introduction.html">Introduction</ulink>, Shorewall is not something
that runs all of the time in your system. Nevertheless, for integrating
Shorewall into your initialization scripts it is useful to speak of
<firstterm>starting</firstterm> Shorewall and
<emphasis>stopping</emphasis> Shorewall.</para>
<itemizedlist>
<listitem>
<para>Shorewall is started using the <command>shorewall
start</command> command. Once the start command completes
successfully, Netfilter is configured as described in your Shorewall
configuration files. If there is an error during <command>shorewall
start</command>, then if you have a <firstterm>saved
configuration</firstterm> then that configuration is restored.
Otherwise, an implicit <command>shorewall stop</command> is
executed.</para>
<important>
<para><command>shorewall start</command> is implemented as a
<firstterm>compile and go</firstterm>; that is, the configuration is
compiled and if there are no compilation errors then the resulting
compiled script is executed. If there are compilation errors, the
command is aborted and the state of the firewall is not
altered.</para>
</important>
</listitem>
<listitem>
<para>Shorewall is stopped using the <command>shorewall stop</command>
command.</para>
<important>
<para>The <command>shorewall stop</command> command does not remove
all Netfilter rules and open your firewall for all traffic to pass.
It rather places your firewall in a safe state defined by the
contents of your <ulink
url="manpages/shorewall-routestopped.html">/etc/shorewall/routestopped</ulink>
file and the setting of ADMINISABSENTMINDED in <ulink
url="manpages/shorewall.conf.html">/etc/shorewall/shorewall.conf</ulink>.</para>
</important>
</listitem>
<listitem>
<para>If you want to remove all Netfilter rules and open your firewall
for all traffic to pass, use the <command>shorewall clear</command>
command.</para>
</listitem>
<listitem>
<para>If you change your configuration and want to install the
changes, use the <command>shorewall restart </command>command.</para>
</listitem>
</itemizedlist>
<para>For additional information, see the<link linkend="State"> Shorewall
State Diagram</link> section.</para>
</section>
<section id="Init">
<title>/etc/init.d/shorewall and /etc/init.d/shorewall-lite</title>
<para>Because of the different requirements of distribution packaging
systems, the behavior of <filename>/etc/init.d/shorewall</filename> and
<filename>/etc/init.d/shorewall-lite</filename> is not consistent between
distributions. As an example, when using the distribution Shorewall
packages on <trademark>Debian</trademark> and
<trademark>Ubuntu</trademark> systems, running
<command>/etc/init.d/shorewall stop</command> will actually execute the
command <command>/sbin/shorewall clear</command> rather than
<command>/sbin/shorewall stop</command>! So don't expect the meaning of
<emphasis>start</emphasis>, <emphasis>stop</emphasis>,
<emphasis>restart</emphasis>, etc. to be consistent between
<filename>/sbin/shorewall</filename> (or
<filename>/sbin/shorewall-lite</filename>) and your init scripts unless
you got your Shorewall package from shorewall.net.</para>
<para><emphasis role="bold">Update:</emphasis><blockquote>
<para>In Shorewall 4.4.0 and later, the tarballs from shorewall.net
follow the Debian convention when installed on a Debian or Ubuntu
system. Beginning with Shorewall 4.4.10, you can revert to the prior
behavior by setting SAFESTOP=1 in
<filename>/etc/default/shorewall</filename>,
<filename>/etc/default/shorewall6</filename>, etc.</para>
</blockquote></para>
</section>
<section id="Trace">
<title>Tracing Command Execution and other Debugging Aids</title>
<para>If you include the word <emphasis role="bold">trace</emphasis> as
the first parameter to an <filename>/sbin/shorewall</filename> command
that transfers control to
<filename>/usr/share/shorewall/firewall</filename>, execution of the
latter program will be traced to STDERR.</para>
<example id="trace">
<title>Tracing <command>shorewall start</command></title>
<para>To trace the execution of <command>shorewall start</command> and
write the trace to the file <filename>/tmp/trace</filename>, you would
enter:<programlisting><command>shorewall trace start 2&gt; /tmp/trace</command></programlisting><note>
<para>The <emphasis role="bold">trace</emphasis> keyword does not
result in a trace of the execution of the Shorewall rules compiler.
It rather causes additional diagnostic information to be included in
warning and error messages generated by the compiler.</para>
</note></para>
<para>You may also include the word <emphasis
role="bold">debug</emphasis> as the first argument to the
<filename>/sbin/shorewall</filename> and
<filename>/sbin/shorewall-lite</filename> commands.<programlisting><command>shorewall debug restart</command></programlisting>In
most cases, <emphasis role="bold">debug</emphasis> is a synonym for
<emphasis role="bold">trace</emphasis>. The exceptions are:</para>
<itemizedlist>
<listitem>
<para><emphasis role="bold">debug</emphasis> is ignored by the
Shorewall-perl compiler.</para>
</listitem>
<listitem>
<para><emphasis role="bold">debug</emphasis> causes altered behavior
of scripts generated by the Shorewall-perl compiler. These scripts
normally use<command> iptables-restore</command> to install the
Netfilter ruleset but with <emphasis role="bold">debug</emphasis>,
the commands normally passed to <command>iptables-restore</command>
in its input file are passed individually to
<command>iptables</command>. This is a diagnostic aid which allows
identifying the individual command that is causing
<command>iptables-restore</command> to fail; it should be used when
iptables-restore fails when executing a <command>COMMIT</command>
command.</para>
</listitem>
</itemizedlist>
<para><warning>
<para>The <emphasis role="bold">debug</emphasis> feature is strictly
for problem analysis. When <emphasis role="bold">debug</emphasis> is
used:</para>
<orderedlist>
<listitem>
<para>The firewall is made 'wide open' before the rules are
applied.</para>
</listitem>
<listitem>
<para>The <filename>routestopped</filename> file is not
consulted.</para>
</listitem>
<listitem>
<para>The rules are applied in the canonical
<command>iptables-restore</command> order. So if you need
critical hosts to be always available during start/restart, you
may not be able to use <emphasis
role="bold">debug</emphasis>.</para>
</listitem>
</orderedlist>
</warning></para>
</example>
</section>
<section id="Boot">
<title>Having Shorewall Start Automatically at Boot Time</title>
<para>The .rpm, .deb and .tgz all try to configure your startup scripts so
that Shorewall will start automatically at boot time. If you are using the
<command>install.sh </command>script from the .tgz and it cannot determine
how to configure automatic startup, a message to that effect will be
displayed. You will need to consult your distribution's documentation to
see how to integrate the <filename>/etc/init.d/shorewall</filename> script
into the distribution's startup mechanism.<caution>
<itemizedlist>
<listitem>
<para>Shorewall startup is disabled by default. Once you have
configured your firewall, you can enable startup by editing
<filename>/etc/shorewall/shorewall.conf</filename> and setting
STARTUP_ENABLED=Yes.. Note: Users of the .deb package must rather
edit <filename>/etc/default/shorewall</filename> and set
<quote>startup=1</quote>.</para>
</listitem>
<listitem>
<para>If you use dialup or some flavor of PPP where your IP
address can change arbitrarily, you may want to start the firewall
in your <command>/etc/ppp/ip-up.local</command> script. I
recommend just placing <quote><command>/sbin/shorewall
restart</command></quote> in that script.</para>
</listitem>
</itemizedlist>
</caution></para>
</section>
<section id="Saved">
<title>Saving a Working Configuration for Error Recovery and Fast
Startup</title>
<para>Once you have Shorewall working the way that you want it to, you can
use <command>shorewall save</command> to <firstterm>save</firstterm> the
commands necessary to recreate that configuration in a <firstterm>restore
script</firstterm>.</para>
<para>In its simplest form, the save command is just:</para>
<programlisting><command>shorewall save</command></programlisting>
<para>That command creates the default restore script,
<filename>/var/lib/shorewall/restore</filename>. The default may be
changed using the RESTOREFILE option in <ulink
url="manpages/shorewall.conf.html">/etc/shorewall/shorewall.conf</ulink>.
A different file name may also be specified in the <command>save</command>
command:</para>
<programlisting><command>shorewall save &lt;filename&gt;</command></programlisting>
<para>Where &lt;<emphasis>filename</emphasis>&gt; is a simple file name
(no slashes).</para>
<para>Once created, the default restore script serves several useful
purposes:</para>
<itemizedlist>
<listitem>
<para>If you change your configuration and there is an error when you
try to restart Shorewall, the restore script will be run to restore
your firewall to working order.</para>
</listitem>
<listitem>
<para>Bootup is faster (although with Shorewall-perl, the difference
is minimal). The -f option of the start command (e.g.,
<command>shorewall -f start</command>) causes Shorewall to look for
the default restore script and if it exists, the script is run. When
using Shorewall-shell, this is much faster than starting Shorewall
using the normal mechanism of reading the configuration files and
running <command>iptables</command> dozens or even hundreds of
times.</para>
<para>The default is to not use -f. If you wish to change the default,
you must set the OPTIONS shell variable in either
<filename>/etc/default/shorewall</filename> or
<filename>/etc/sysconfig/shorewall</filename> (if your distribution
provides neither of these files, you must create one or the
other).</para>
<para><emphasis role="bold">Update</emphasis>: In Shorewall 4.4.20, a
new LEGACY_FASTSTART option was added to <ulink
url="manpages/shorewall.conf.html">/etc/shorewall/shorewall.conf</ulink>.
When LEGACY_FASTSTART=No, the compiled script that did the last
successful <command role="bold">start</command> or <command
role="bold">restart</command> will be used.</para>
</listitem>
<listitem>
<para>The <command>shorewall restore</command> command can be used at
any time to quickly configure the firewall.</para>
<programlisting><command>shorewall restore [ &lt;filename&gt; ]</command></programlisting>
<para>If no &lt;<emphasis>filename</emphasis>&gt; is given, the
default restore script is used. Otherwise, the script
<filename>/var/lib/shorewall/&lt;filename&gt;</filename> is
used.</para>
</listitem>
</itemizedlist>
<para>The ability to have multiple restore scripts means that you can save
different Shorewall firewall configurations and switch between them
quickly using the <command>restore</command> command.</para>
<para>Restore scripts may be removed using the <command>shorewall
forget</command> command:</para>
<programlisting><command>shorewall forget [ &lt;filename&gt; ]</command></programlisting>
<para>If no &lt;<emphasis>filename</emphasis>&gt; is given, the default
restore script is removed. Otherwise,
<filename>/var/lib/shorewall/&lt;filename&gt;</filename> is removed (of
course, you can also use the Linux <command>rm</command> command from the
shell prompt to remove these files).</para>
</section>
<section id="AddDirectories">
<title>Additional Configuration Directories</title>
<para>The CONFIG_PATH setting in
<filename>/etc/shorewall/shorewall.conf</filename> determines where
Shorewall looks for configuration files. The default setting is
CONFIG_PATH=<filename
class="directory">/etc/shorewall</filename>:<filename
class="directory">/usr/share/shorewall</filename> which means that
<filename class="directory">/etc/shorewall</filename> is searched first
and if the file is not found then <filename
class="directory">/usr/share/shorewall</filename> is searched. You can
change the value of CONFIG_PATH to cause additional directories to be
searched but CONFIG_PATH should <emphasis>always</emphasis> include both
<filename class="directory">/etc/shorewall</filename> and <filename
class="directory">/usr/share/shorewall</filename>.</para>
<para>When an alternate configuration directory is specified as described
in the <link linkend="AddDirectories">next section</link>, that directory
is searched <emphasis>before</emphasis> those directories listed in
CONFIG_PATH.</para>
<para>Example - Search <filename
class="directory">/etc/shorewall</filename>, <filename
class="directory">/etc/shorewall/actiondir</filename> and <filename
class="directory">/usr/share/shorewall</filename> in that order:</para>
<programlisting>CONFIG_PATH=/etc/shorewall:/etc/shorewall/actiondir:/usr/share/shorewall</programlisting>
<para>The above is the setting that I once used to allow me to place all
of my user-defined 'action.' files in <filename
class="directory">/etc/shorewall/actiondir</filename>.</para>
</section>
<section id="AltConfig">
<title>Alternate Configuration Directories</title>
<para>As explained <link linkend="AddDirectories">above</link>, Shorewall
normally looks for configuration files in the directories specified by the
CONFIG_PATH option in <filename
class="directory">/etc/shorewall/shorewall.conf</filename>. The
<command>shorewall start</command>, <command>shorewall restart</command>,
<command>shorewall check</command>, and <command>shorewall try
</command>commands allow you to specify an additional directory for
Shorewall to check before looking in the directories listed in
CONFIG_PATH.</para>
<programlisting> <command>shorewall {start|restart|check} &lt;configuration-directory&gt;</command>
<command>shorewall try &lt;configuration-directory&gt; [ &lt;timeout&gt; ]</command></programlisting>
<para>If a <emphasis>&lt;configuration-directory</emphasis>&gt; is
specified, each time that Shorewall is going to read a file, it will first
look in the<emphasis> &lt;configuration-directory&gt;</emphasis> . If the
file is present in the
<emphasis>&lt;configuration-directory&gt;,</emphasis> that file will be
used; otherwise, the directories in the CONFIG_PATH will be searched. When
changing the configuration of a production firewall, I recommend the
following:</para>
<itemizedlist>
<listitem>
<para>If you haven't saved the current working configuration, do so
using <command>shorewall save</command>.</para>
</listitem>
<listitem>
<para><command>mkdir /etc/test</command></para>
</listitem>
<listitem>
<para><command>cd /etc/test</command></para>
</listitem>
<listitem>
<para>&lt;copy any files that you need to change from /etc/shorewall
to . and change them here&gt;</para>
</listitem>
<listitem>
<para><command>shorewall check ./</command></para>
</listitem>
<listitem>
<para>&lt;correct any errors found by check and check again&gt;</para>
</listitem>
<listitem>
<para><command>shorewall restart ./</command></para>
</listitem>
</itemizedlist>
<para>If the <command>restart</command> fails, your configuration will be
restored to its state at the last <command>shorewall
save</command>.</para>
<para>When the new configuration works then just:</para>
<itemizedlist>
<listitem>
<para><command>cp -f * /etc/shorewall</command></para>
</listitem>
<listitem>
<para><command>cd</command></para>
</listitem>
<listitem>
<para><command>rm -rf /etc/test</command></para>
</listitem>
<listitem>
<para><command>shorewall save</command></para>
</listitem>
</itemizedlist>
<important>
<para>Shorewall requires that the file
<filename>/etc/shorewall/shorewall.conf</filename> to always exist.
Certain global settings are always obtained from that file. If you
create alternative configuration directories, do not remove
/etc/shorewall/shorewall.conf.</para>
</important>
</section>
<section id="Commands">
<title>Commands</title>
<para>The general form of a command is:</para>
<blockquote>
<para><command>shorewall [ &lt;options&gt; ] &lt;command&gt; [
&lt;command options&gt; ] [ &lt;argument&gt; ... ]</command></para>
<para>Available options are:</para>
<variablelist>
<varlistentry>
<term>-c &lt;directory&gt;</term>
<listitem>
<para>Specifies an <link linkend="AltConfig">alternate
configuration directory</link>. Use of this option is
deprecated.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>-f</term>
<listitem>
<para>Specifies fast restart. See the <command>start</command>
command below.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>-n</term>
<listitem>
<para>Prevents the command from changing the firewall system's
routing configuration.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>-q</term>
<listitem>
<para>Reduces the verbosity level (see VERBOSITY setting in <ulink
url="manpages/shorewall.conf.htmlig">shorewall.conf</ulink>). May
be repeated (e.g., "-qq") with each instance reducing the
verbosity level by one.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>-v</term>
<listitem>
<para>Increases the verbosity level (see VERBOSITY setting in
<ulink
url="manpages/shorewall.conf.htmlig">shorewall.conf</ulink>). May
be repeated (e.g., "-vv") with each instance increasing the
verbosity level by one.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>-x</term>
<listitem>
<para>Causes all iptables -L commands to display actual packet and
byte counts.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>-t</term>
<listitem>
<para>All progress messages are timestamped with the date and
time.</para>
</listitem>
</varlistentry>
</variablelist>
<para>In addition, the <command>-q</command> and <command>-v</command>
options may be repeated to make the output less or more verbose
respectively. The default level of verbosity is determined by the
setting of the VERBOSITY option in
<filename>/etc/shorewall/shorewall.conf</filename>.</para>
<para>For Shorewall Lite, the general command form is:</para>
<para><command>shorewall-lite [ &lt;options&gt; ] &lt;command&gt; [
&lt;command options&gt; ] [ &lt;argument&gt; ... ]</command></para>
<para>where the options are the same as with Shorewall.</para>
<para>The complete documentation for each command may be found in the
<ulink url="manpages/shorewall.html">shorewall</ulink> and <ulink
url="manpages/shorewall-lite.html">shorewall-lite</ulink> man
pages.</para>
</blockquote>
</section>
<section id="State">
<title>Shorewall State Diagram</title>
<para>The Shorewall State Diagram is depicted below.</para>
<para><graphic align="center" fileref="images/State_Diagram.png" /></para>
<informaltable>
<tgroup cols="3">
<thead>
<row>
<entry align="center">/sbin/shorewall Command</entry>
<entry align="center">Resulting /usr/share/shorewall/firewall
Command</entry>
<entry align="center">Effect if the Command Succeeds</entry>
</row>
</thead>
<tbody>
<row>
<entry>shorewall start</entry>
<entry>firewall start</entry>
<entry>The system filters packets based on your current Shorewall
Configuration</entry>
</row>
<row>
<entry>shorewall stop</entry>
<entry>firewall stop</entry>
2011-05-08 14:37:49 +02:00
<entry>Only traffic to/from hosts listed in
/etc/shorewall/routestopped is passed to/from/through the
firewall. If ADMINISABSENTMINDED=Yes in
/etc/shorewall/shorewall.conf then in addition, all existing
connections are retained and all connection requests from the
firewall are accepted.</entry>
</row>
<row>
<entry>shorewall restart</entry>
<entry>firewall restart</entry>
<entry>Logically equivalent to <quote>firewall stop;firewall
start</quote></entry>
</row>
<row>
<entry>shorewall add</entry>
<entry>firewall add</entry>
<entry>Adds a host or subnet to a dynamic zone</entry>
</row>
<row>
<entry>shorewall delete</entry>
<entry>firewall delete</entry>
<entry>Deletes a host or subnet from a dynamic zone</entry>
</row>
<row>
<entry>shorewall refresh</entry>
<entry>firewall refresh</entry>
<entry>Reloads rules dealing with static blacklisting, traffic
control and ECN.</entry>
</row>
<row>
<entry>shorewall reset</entry>
<entry>firewall reset</entry>
<entry>Resets traffic counters</entry>
</row>
<row>
<entry>shorewall clear</entry>
<entry>firewall clear</entry>
<entry>Removes all Shorewall rules, chains, addresses, routes and
ARP entries.</entry>
</row>
<row>
<entry>shorewall try</entry>
<entry>firewall -c &lt;new configuration&gt; restart If
unsuccessful then firewall start (standard configuration) If
timeout then firewall restart (standard configuration)</entry>
<entry></entry>
</row>
</tbody>
</tgroup>
</informaltable>
<para>The only time that a program other than
<command>/usr/share/shorewall[-lite[/firewall</command> performs a state
transition itself is when the <command>shorewall[-lite] restore</command>
command is executed. In that case, the
<command>/var/lib/shorewall[-lite]/restore</command> program sets the
state to "Started".</para>
<para>With any command that involves compilation, there is no state
transition while the compiler is running. If compilation fails, the state
remains unchanged.</para>
<para>Also, <command>shorewall start</command> and <command>shorewall
restart</command> involve compilation followed by execution of the
compiled script. So it is the compiled script that performs the state
transition in these commands rather than
<command>/usr/share/shorewall/firewall</command>.</para>
<para>The compiled script is placed in <filename
class="directory">/var/lib/shorewall</filename> and is named either
<filename>.start</filename> or <filename>.restart</filename> depending on
the command.</para>
</section>
</article>