shorewall_code/docs/CompiledPrograms.xml

<?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>Shorewall Lite and Compiled Firewall Programs</title>

    <authorgroup>
      <author>
        <firstname>Tom</firstname>

        <surname>Eastep</surname>
      </author>
    </authorgroup>

    <pubdate><?dbtimestamp format="Y/m/d"?></pubdate>

    <copyright>
      <year>2006-2010</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 appropriate for your
    version.</emphasis></para>
  </caution>

  <section id="Overview">
    <title>Overview</title>

    <para>Shorewall has the capability to compile a Shorewall configuration
    and produce a runnable firewall program script. The script is a complete
    program which can be placed on a system with <emphasis>Shorewall
    Lite</emphasis> installed and can serve as the firewall creation script
    for that system.</para>

    <section id="Lite">
      <title>Shorewall Lite</title>

      <para>Shorewall Lite is a companion product to Shorewall and is designed
      to allow you to maintain all Shorewall configuration information on a
      single system within your network.</para>

      <orderedlist numeration="loweralpha">
        <listitem>
          <para>You install the full Shorewall release on one system within
          your network. You need not configure Shorewall there and you may
          totally disable startup of Shorewall in your init scripts. For ease
          of reference, we call this system the 'administrative
          system'.</para>

          <para>The administrative system may be a GNU/Linux system, a Windows
          system running <ulink url="http://www.cygwin.com/">Cygwin</ulink> or
          an <ulink url="http://www.apple.com/mac/">Apple MacIntosh</ulink>
          running OS X. Install from a shell prompt <ulink
          url="Install.htm">using the install.sh script</ulink>.</para>
        </listitem>

        <listitem>
          <para>On each system where you wish to run a Shorewall-generated
          firewall, you install Shorewall Lite. For ease of reference, we will
          call these systems the 'firewall systems'.</para>

          <note>
            <para>The firewall systems do <emphasis role="bold">NOT</emphasis>
            need to have the full Shorewall product installed but rather only
            the Shorewall Lite product. Shorewall and Shorewall Lite may be
            installed on the same system but that isn't encouraged.</para>
          </note>
        </listitem>

        <listitem>
          <para>On the administrative system you create a separate 'export
          directory' for each firewall system. You copy the contents of
          <filename
          class="directory">/usr/share/shorewall/configfiles</filename> into
          each export directory.</para>

          <note>
            <para>Users of Debian and derivatives that install the package
            from their distribution will be disappointed to find that
            <filename
            class="directory">/usr/share/shorewall/configfiles</filename> does
            not exist on their systems. They will instead need to
            either:</para>

            <itemizedlist>
              <listitem>
                <para>Copy the files in
                /usr/share/doc/shorewall/default-config/ into each export
                directory.</para>
              </listitem>

              <listitem>
                <para>Copy /etc/shorewall/shorewall.conf into each export
                directory and remove /etc/shorewall from the CONFIG_PATH
                setting in the copied files.</para>
              </listitem>
            </itemizedlist>

            <para>or</para>

            <itemizedlist>
              <listitem>
                <para>Download the Shorewall tarball corresponding to their
                package version.</para>
              </listitem>

              <listitem>
                <para>Untar and copy the files from the
                <filename>configfiles</filename> sub-directory in the untarred
                <filename>shorewall-...</filename> directory.</para>
              </listitem>
            </itemizedlist>
          </note>

          <para>After copying, you may need to change two setting in the copy
          of shorewall.conf:</para>

          <itemizedlist>
            <listitem>
              <para>Remove /etc/shorewall (/etc/shorewal6) from the setting of
              CONFIG_PATH</para>
            </listitem>

            <listitem>
              <para>STARTUP_LOG=/var/log/shorewall-lite-init.log</para>
            </listitem>
          </itemizedlist>

          <para>Older versions of Shorewall included copies of shorewall.conf
          with these settings already modified. This practice was discontinued
          in Shorewall 4.4.20.1.</para>
        </listitem>

        <listitem>
          <para>The <filename>/etc/shorewall/shorewall.conf</filename> file is
          used to determine the VERBOSITY setting which determines how much
          output the compiler generates. All other settings are taken from the
          <filename>shorewall.conf </filename>file in the remote systems
          export directory.</para>

          <caution>
            <para>If you want to be able to allow non-root users to manage
            remote firewall systems, then the files
            <filename>/etc/shorewall/params</filename> and
            <filename>/etc/shorewall/shorewall.conf</filename> must be
            readable by all users on the administrative system. Not all
            packages secure the files that way and you may have to change the
            file permissions yourself.</para>
          </caution>
        </listitem>

        <listitem id="Debian">
          <para>On each firewall system, If you are running Debian or one of
          its derivatives like Ubuntu then edit
          <filename>/etc/default/shorewall-lite</filename> and set
          startup=1.</para>
        </listitem>

        <listitem>
          <para>On the administrative system, for each firewall system you do
          the following (this may be done by a non-root user who has root ssh
          access to the firewall system):</para>

          <orderedlist>
            <listitem>
              <para>modify the files in the corresponding export directory
              appropriately (i.e., <emphasis>just as you would if you were
              configuring Shorewall on the firewall system itself</emphasis>).
              It's a good idea to include the IP address of the administrative
              system in the <ulink
              url="manpages/shorewall-stoppedrules.html"><filename>stoppedrules
              </filename> file</ulink>.</para>

              <para>It is important to understand that with Shorewall Lite,
              the firewall's export directory on the administrative system
              acts as <filename class="directory">/etc/shorewall</filename>
              for that firewall. So when the Shorewall documentation gives
              instructions for placing entries in files in the firewall's
              <filename class="directory">/etc/shorewall</filename>, when
              using Shorewall Lite you make those changes in the firewall's
              export directory on the administrative system.</para>

              <para>The CONFIG_PATH variable is treated as follows:</para>

              <itemizedlist>
                <listitem>
                  <para>The value of CONFIG_PATH in
                  <filename>/etc/shorewall/shorewall.conf</filename> is
                  ignored when compiling for export (the -e option in given)
                  and when the <command>load</command> or
                  <command>reload</command> command is being executed (see
                  below).</para>
                </listitem>

                <listitem>
                  <para>The value of CONFIG_PATH in the
                  <filename>shorewall.conf</filename> file in the export
                  directory is used to search for configuration files during
                  compilation of that configuration.</para>
                </listitem>

                <listitem>
                  <para>The value of CONFIG_PATH used when the script is run
                  on the firewall system is
                  "/etc/shorewall-lite:/usr/share/shorewall-lite".</para>
                </listitem>
              </itemizedlist>
            </listitem>

            <listitem>
              <programlisting><command>cd &lt;export directory&gt;</command>
<command>/sbin/shorewall load firewall</command></programlisting>

              <para>The <ulink
              url="starting_and_stopping_shorewall.htm#Load"><command>load</command></ulink>
              command compiles a firewall script from the configuration files
              in the current working directory (using <command>shorewall
              compile -e</command>), copies that file to the remote system via
              scp and starts Shorewall Lite on the remote system via
              ssh.</para>

              <para>Example (firewall's DNS name is 'gateway'):</para>

              <para><command>/sbin/shorewall load gateway</command><note>
                  <para>Although scp and ssh are used by default, you can use
                  other utilities by setting RSH_COMMAND and RCP_COMMAND in
                  <filename>/etc/shorewall/shorewall.conf</filename>.</para>
                </note></para>

              <para>The first time that you issue a <command>load</command>
              command, Shorewall will use ssh to run
              <filename>/usr/share/shorewall-lite/shorecap</filename> on the
              remote firewall to create a capabilities file in the firewall's
              administrative direction. See <link
              linkend="Shorecap">below</link>.</para>
            </listitem>
          </orderedlist>
        </listitem>

        <listitem>
          <para>If you later need to change the firewall's configuration,
          change the appropriate files in the firewall's export directory
          then:</para>

          <programlisting><command>cd &lt;export directory&gt;</command>
<command>/sbin/shorewall reload firewall</command></programlisting>

          <para>The <ulink
          url="manpages/shorewall.html"><command>reload</command></ulink>
          command compiles a firewall script from the configuration files in
          the current working directory (using <command>shorewall compile
          -e</command>), copies that file to the remote system via scp and
          restarts Shorewall Lite on the remote system via ssh. The <emphasis
          role="bold">reload</emphasis> command also supports the '-c'
          option.</para>

          <para>I personally place a <filename>Makefile</filename> in each
          export directory as follows:</para>

          <blockquote>
            <programlisting>#     Shorewall Packet Filtering Firewall Export Directory Makefile - V3.3
#
#     This program is under GPL [http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt]
#
#     (c) 2006 - Tom Eastep (teastep@shorewall.net)
#
#       Shorewall documentation is available at http://www.shorewall.net
#
#       This program is free software; you can redistribute it and/or modify
#       it under the terms of Version 2 of the GNU General Public License
#       as published by the Free Software Foundation.
#
#       This program is distributed in the hope that it will be useful,
#       but WITHOUT ANY WARRANTY; without even the implied warranty of
#       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
#       GNU General Public License for more details.
#
#       You should have received a copy of the GNU General Public License
#       along with this program; if not, write to the Free Software
#       Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
################################################################################
# Place this file in each export directory. Modify each copy to set HOST
# to the name of the remote firewall corresponding to the directory.
#
#       To make the 'firewall' script, type "make".
# 
#       Once the script is compiling correctly, you can install it by
#       typing "make install".
#  
################################################################################
#                             V A R I A B L E S
#
# Files in the export directory on which the firewall script does not depend
#
IGNOREFILES =  firewall% Makefile% trace% %~
#
# Remote Firewall system
#
HOST = gateway
#
# Save some typing
#
LITEDIR = /var/lib/shorewall-lite
#
# Set this if the remote system has a non-standard modules directory
#
MODULESDIR=
#
# Default target is the firewall script
#
################################################################################
#                                T A R G E T S
#
all: firewall
#
# Only generate the capabilities file if it doesn't already exist
#
capabilities: 
        ssh root@$(HOST) "MODULESDIR=$(MODULESDIR) /usr/share/shorewall-lite/shorecap &gt; $(LITEDIR)/capabilities"
        scp root@$(HOST):$(LITEDIR)/capabilities .
#
# Compile the firewall script. Using the 'wildcard' function causes "*" to be expanded so that
# 'filter-out' will be presented with the list of files in this directory rather than "*"
#
firewall: $(filter-out $(IGNOREFILES) capabilities , $(wildcard *) ) capabilities
        shorewall compile -e . firewall
#
# Only reload on demand.
#
install: firewall
        scp firewall firewall.conf root@$(HOST):$(LITEDIR)
        ssh root@$(HOST) "/sbin/shorewall-lite restart"
#
# Save running configuration
#
save:
        ssh root@$(HOST) "/sbin/shorewall-lite save"
#
# Remove generated files
#
clean: 
        rm -f capabilities firewall firewall.conf reload
</programlisting>
          </blockquote>

          <para>That way, after I've changed the configuration, I can simply
          type <command>make</command> or <emphasis role="bold">make
          install</emphasis>.</para>

          <note>
            <para>The above Makefile is available at <ulink
            url="http://www1.shorewall.net/pub/shorewall/contrib/Shorewall-lite/">http://www.shorewall.net/pub/shorewall/contrib/Shorewall-lite/</ulink></para>
          </note>

          <note>
            <para>I omit trace% because I often trace compiler execution while
            I'm debugging new versions of Shorewall.</para>
          </note>
        </listitem>
      </orderedlist>

      <para>There is a <filename>shorewall-lite.conf</filename> file installed
      as part of Shorewall Lite
      (<filename>/etc/shorewall-lite/shorewall-lite.conf</filename>). You can
      use that file on the firewall system to override some of the settings
      from the shorewall.conf file in the export directory.</para>

      <para>Settings that you can override are:</para>

      <blockquote>
        <simplelist>
          <member>VERBOSITY</member>

          <member>LOGFILE</member>

          <member>LOGFORMAT</member>

          <member>IPTABLES</member>

          <member>PATH</member>

          <member>SHOREWALL_SHELL</member>

          <member>SUBSYSLOCK</member>

          <member>RESTOREFILE</member>
        </simplelist>
      </blockquote>

      <para>You will normally never touch
      <filename>/etc/shorewall-lite/shorewall-lite.conf</filename> unless you
      run Debian or one of its derivatives (see <link
      linkend="Debian">above</link>).</para>

      <para>The <filename>/sbin/shorewall-lite</filename> program included
      with Shorewall Lite supports the same set of commands as the
      <filename>/sbin/shorewall</filename> program in a full Shorewall
      installation with the following exceptions:</para>

      <blockquote>
        <simplelist>
          <member>add</member>

          <member>compile</member>

          <member>delete</member>

          <member>refresh</member>

          <member>reload</member>

          <member>try</member>

          <member>safe-start</member>

          <member>safe-restart</member>

          <member>show actions</member>

          <member>show macros</member>
        </simplelist>
      </blockquote>

      <para>On systems with only Shorewall Lite installed, I recommend that
      you create a symbolic link <filename>/sbin/shorewall</filename> and
      point it at <filename>/sbin/shorewall-lite</filename>. That way, you can
      use <command>shorewall</command> as the command regardless of which
      product is installed.</para>

      <blockquote>
        <programlisting><command>ln -sf shorewall-lite /sbin/shorewall</command></programlisting>
      </blockquote>

      <section>
        <title>Module Loading</title>

        <para>As with a normal Shorewall configuration, the shorewall.conf
        file can specify LOAD_HELPERS_ONLY which determines if the
        <filename>modules</filename> file (LOAD_HELPERS_ONLY=No) or
        <filename>helpers</filename> file (LOAD_HELPERS_ONLY=Yes) is used.
        Normally, the file on the firewall system is used. If you want to
        specify modules at compile time on the Administrative System, then you
        must place a copy of the appropriate file
        (<filename>modules</filename> or <filename>helpers</filename>) in the
        firewall's configuration directory before compilation.</para>

        <para>In Shorewall 4.4.17, the EXPORTMODULES option was added to
        shorewall.conf (and shorewall6.conf). When EXPORTMODULES=Yes, any
        <filename>modules</filename> or <filename>helpers</filename> file
        found on the CONFIG_PATH on the Administrative System during
        compilation will be used.</para>
      </section>

      <section id="Converting">
        <title>Converting a system from Shorewall to Shorewall Lite</title>

        <para>Converting a firewall system that is currently running Shorewall
        to run Shorewall Lite instead is straight-forward.</para>

        <orderedlist numeration="loweralpha">
          <listitem>
            <para>On the administrative system, create an export directory for
            the firewall system.</para>
          </listitem>

          <listitem>
            <para>Copy the contents of <filename
            class="directory">/etc/shorewall/</filename> from the firewall
            system to the export directory on the administrative
            system.</para>
          </listitem>

          <listitem>
            <para>On the firewall system:</para>

            <para>Be sure that the IP address of the administrative system is
            included in the firewall's export directory
            <filename>stoppedrules</filename> file.</para>

            <programlisting><command>shorewall stop</command></programlisting>

            <para><emphasis role="bold">We recommend that you uninstall
            Shorewall at this point.</emphasis></para>
          </listitem>

          <listitem>
            <para>Install Shorewall Lite on the firewall system.</para>

            <para>If you are running Debian or one of its derivatives like
            Ubuntu then edit <filename>/etc/default/shorewall-lite</filename>
            and set startup=1.</para>
          </listitem>

          <listitem>
            <para>On the administrative system:</para>

            <para>It's a good idea to include the IP address of the
            administrative system in the firewall system's <ulink
            url="manpages/shorewall-stoppedrules.html"><filename>stoppedrules</filename>
            file</ulink>.</para>

            <para>Also, edit the <filename>shorewall.conf</filename> file in
            the firewall's export directory and change the CONFIG_PATH setting
            to remove <filename class="directory">/etc/shorewall</filename>.
            You can replace it with <filename
            class="directory">/usr/share/shorewall/configfiles</filename> if
            you like.</para>

            <para>Example:</para>

            <blockquote>
              <para>Before editing:</para>

              <programlisting>CONFIG_PATH=<emphasis role="bold">/etc/shorewall</emphasis>:/usr/share/shorewall</programlisting>

              <para>After editing:</para>

              <programlisting>CONFIG_PATH=<emphasis role="bold">/usr/share/shorewall/configfiles</emphasis>:/usr/share/shorewall</programlisting>
            </blockquote>

            <para>Changing CONFIG_PATH will ensure that subsequent
            compilations using the export directory will not include any files
            from <filename class="directory">/etc/shorewall</filename> other
            than <filename>shorewall.conf</filename> and
            <filename>params</filename>.</para>

            <para>If you set variables in the params file, there are a couple
            of issues:</para>

            <para>The <filename>params</filename> file is not processed at run
            time if you set EXPORTPARAMS=No in
            <filename>shorewall.conf</filename>. For run-time setting of shell
            variables, use the <filename>init</filename> extension script.
            Beginning with Shorewall 4.4.17, the variables set in the
            <filename>params</filename> file are available in the firewall
            script when EXPORTPARAMS=No.</para>

            <para>If the <filename>params</filename> file needs to set shell
            variables based on the configuration of the firewall system, you
            can use this trick:</para>

            <programlisting>EXT_IP=$(ssh root@firewall "/sbin/shorewall-lite call find_first_interface_address eth0")</programlisting>

            <para>The <command>shorewall-lite call</command> command allows
            you to to call interactively any Shorewall function that you can
            call in an extension script.</para>

            <para>After having made the above changes to the firewall's export
            directory, execute the following commands.</para>

            <blockquote>
              <programlisting><command>cd &lt;export directory&gt;</command>
<command>/sbin/shorewall load &lt;firewall system&gt;</command>
</programlisting>

              <para>Example (firewall's DNS name is 'gateway'):</para>

              <para><command>/sbin/shorewall load gateway</command></para>
            </blockquote>

            <para>The first time that you issue a <command>load</command>
            command, Shorewall will use ssh to run
            <filename>/usr/share/shorewall-lite/shorecap</filename> on the
            remote firewall to create a capabilities file in the firewall's
            administrative direction. See <link
            linkend="Shorecap">below</link>.</para>

            <para>The <ulink
            url="starting_and_stopping_shorewall.htm#Load"><command>load</command></ulink>
            command compiles a firewall script from the configuration files in
            the current working directory (using <command>shorewall compile
            -e</command>), copies that file to the remote system via
            <command>scp</command> and starts Shorewall Lite on the remote
            system via <command>ssh</command>.</para>
          </listitem>

          <listitem>
            <para>If you later need to change the firewall's configuration,
            change the appropriate files in the firewall's export directory
            then:</para>

            <programlisting><command>cd &lt;export directory&gt;</command>
<command>/sbin/shorewall reload firewall</command></programlisting>

            <para>The <ulink
            url="starting_and_stopping_shorewall.htm#Reload"><command>reload</command></ulink>
            command compiles a firewall script from the configuration files in
            the current working directory (using <command>shorewall compile
            -e</command>), copies that file to the remote system via
            <command>scp</command> and restarts Shorewall Lite on the remote
            system via <command>ssh</command>.</para>
          </listitem>

          <listitem>
            <para>If the kernel/iptables configuration on the firewall later
            changes and you need to create a new
            <filename>capabilities</filename> file, do the following on the
            firewall system:</para>

            <programlisting><command>/usr/share/shorewall-lite/shorecap &gt; capabilities</command>
<command>scp capabilities &lt;admin system&gt;:&lt;this system's config dir&gt;</command></programlisting>

            <para>Or simply use the -c option the next time that you use the
            <command>reload</command> command (e.g., <command>shorewall reload
            -c gateway</command>).</para>
          </listitem>
        </orderedlist>
      </section>
    </section>

    <section id="Restrictions">
      <title>Restrictions</title>

      <para>While compiled Shorewall programs (as are used in Shorewall Lite)
      are useful in many cases, there are some important restrictions that you
      should be aware of before attempting to use them.</para>

      <orderedlist>
        <listitem>
          <para>All extension scripts used are copied into the program (with
          the exception of <ulink url="shorewall_extension_scripts.htm">those
          executed at compile-time by the compiler</ulink>). The ramifications
          of this are:</para>

          <itemizedlist>
            <listitem>
              <para>If you update an extension script, the compiled program
              will not use the updated script.</para>
            </listitem>

            <listitem>
              <para>The <filename>params</filename> file is only processed at
              compile time if you set EXPORTPARAMS=No in
              <filename>shorewall.conf</filename>. For run-time setting of
              shell variables, use the <filename>init</filename> extension
              script. Although the default setting is EXPORTPARAMS=Yes for
              compatibility, the recommended setting is EXPORTPARAMS=No.
              Beginning with Shorewall 4.4.17, the variables set in the
              <filename>params</filename> file are available in the firewall
              script when EXPORTPARAMS=No.</para>

              <para>If the <filename>params</filename> file needs to set shell
              variables based on the configuration of the firewall system, you
              can use this trick:</para>

              <programlisting>EXT_IP=$(ssh root@firewall "/sbin/shorewall-lite call find_first_interface_address eth0")</programlisting>

              <para>The <command>shorewall-lite call</command> command allows
              you to to call interactively any Shorewall function that you can
              call in an extension script.</para>
            </listitem>
          </itemizedlist>
        </listitem>

        <listitem>
          <para>You must install Shorewall Lite on the system where you want
          to run the script. You then install the compiled program in
          /usr/share/shorewall-lite/firewall and use the /sbin/shorewall-lite
          program included with Shorewall Lite to control the firewall just as
          if the full Shorewall distribution was installed.</para>
        </listitem>
      </orderedlist>
    </section>
  </section>

  <section id="Compile">
    <title>The "shorewall compile" command</title>

    <para>A compiled script is produced using the <command>compile</command>
    command:</para>

    <blockquote>
      <para><command>shorewall compile [ -e ] [ &lt;directory name&gt; ] [
      &lt;path name&gt; ]</command></para>
    </blockquote>

    <para>where</para>

    <blockquote>
      <variablelist>
        <varlistentry>
          <term>-e</term>

          <listitem>
            <para>Indicates that the program is to be "exported" to another
            system. When this flag is set, neither the "detectnets" interface
            option nor DYNAMIC_ZONES=Yes in shorewall.conf are allowed. The
            created program may be run on a system that has only Shorewall
            Lite installed</para>

            <para>When this flag is given, Shorewall does not probe the
            current system to determine the kernel/iptables features that it
            supports. It rather reads those capabilities from
            <filename>/etc/shorewall/capabilities</filename>. See below for
            details.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>&lt;directory name&gt;</term>

          <listitem>
            <para>specifies a directory to be searched for configuration files
            before those directories listed in the CONFIG_PATH variable in
            <filename>shorewall.conf</filename>.</para>

            <para>When -e &lt;directory-name&gt; is included, only the
            SHOREWALL_SHELL and VERBOSITY settings from
            <filename>/etc/shorewall/shorewall.conf</filename> are used and
            these apply only to the compiler itself. The settings used by the
            compiled firewall script are determined by the contents of
            <filename>&lt;directory name&gt;/shorewall.conf</filename>.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>&lt;path name&gt;</term>

          <listitem>
            <para>specifies the name of the script to be created. If not
            given, ${VARDIR}/firewall is assumed (by default, ${VARDIR} is
            <filename>/var/lib/shorewall/</filename>)</para>
          </listitem>
        </varlistentry>
      </variablelist>
    </blockquote>
  </section>

  <section id="Shorecap">
    <title>The /etc/shorewall/capabilities file and the shorecap
    program</title>

    <para>As mentioned above, the
    <filename>/etc/shorewall/capabilities</filename> file specifies that
    kernel/iptables capabilities of the target system. Here is a sample
    file:</para>

    <blockquote>
      <programlisting>#
# Shorewall detected the following iptables/netfilter capabilities - Tue Jul 15 07:28:12 PDT 2008
#
NAT_ENABLED=Yes
MANGLE_ENABLED=Yes
MULTIPORT=Yes
XMULTIPORT=Yes
CONNTRACK_MATCH=Yes
USEPKTTYPE=Yes
POLICY_MATCH=Yes
PHYSDEV_MATCH=Yes
PHYSDEV_BRIDGE=Yes
LENGTH_MATCH=Yes
IPRANGE_MATCH=Yes
RECENT_MATCH=Yes
OWNER_MATCH=Yes
IPSET_MATCH=Yes
CONNMARK=Yes
XCONNMARK=Yes
CONNMARK_MATCH=Yes
XCONNMARK_MATCH=Yes
RAW_TABLE=Yes
IPP2P_MATCH=
CLASSIFY_TARGET=Yes
ENHANCED_REJECT=Yes
KLUDGEFREE=Yes
MARK=Yes
XMARK=Yes
MANGLE_FORWARD=Yes
COMMENTS=Yes
ADDRTYPE=Yes
TCPMSS_MATCH=Yes
HASHLIMIT_MATCH=Yes
NFQUEUE_TARGET=Yes
REALM_MATCH=Yes
CAPVERSION=40190</programlisting>
    </blockquote>

    <para>As you can see, the file contains a simple list of shell variable
    assignments — the variables correspond to the capabilities listed by the
    <command>shorewall show capabilities</command> command and they appear in
    the same order as the output of that command.</para>

    <para>To aid in creating this file, Shorewall Lite includes a
    <command>shorecap</command> program. The program is installed in the
    <filename class="directory">/usr/share/shorewall-lite/</filename>
    directory and may be run as follows:</para>

    <blockquote>
      <para><command>[ IPTABLES=&lt;iptables binary&gt; ] [
      MODULESDIR=&lt;kernel modules directory&gt; ]
      /usr/share/shorewall-lite/shorecap &gt; capabilities</command></para>
    </blockquote>

    <para>The IPTABLES and MODULESDIR options have their <ulink
    url="manpages/shorewall.conf.html">usual Shorewall default
    values</ulink>.</para>

    <para>The <filename>capabilities</filename> file may then be copied to a
    system with Shorewall installed and used when compiling firewall programs
    to run on the remote system.</para>

    <para>The <filename>capabilities</filename> file may also be creating
    using <filename>/sbin/shorewall-lite</filename>:<blockquote>
        <para><command>shorewall-lite show -f capabilities &gt;
        capabilities</command></para>
      </blockquote></para>

    <para>Note that unlike the <command>shorecap</command> program, the
    <command>show capabilities</command> command shows the kernel's current
    capabilities; it does not attempt to load additional kernel
    modules.</para>
  </section>

  <section id="Running">
    <title>Running compiled programs directly</title>

    <para>Compiled firewall programs are complete shell programs that support
    the following command line forms:</para>

    <blockquote>
      <simplelist>
        <member><command>&lt;program&gt; [ -q ] [ -v ] [ -n ]
        start</command></member>

        <member><command>&lt;program&gt; [ -q ] [ -v ] [ -n ]
        stop</command></member>

        <member><command>&lt;program&gt; [ -q ] [ -v ] [ -n ]
        clear</command></member>

        <member><command>&lt;program&gt; [ -q ] [ -v ] [ -n ]
        refresh</command></member>

        <member><command>&lt;program&gt; [ -q ] [ -v ] [ -n ]
        reset</command></member>

        <member><command>&lt;program&gt; [ -q ] [ -v ] [ -n ]
        restart</command></member>

        <member><command>&lt;program&gt; [ -q ] [ -v ] [ -n ]
        status</command></member>

        <member><command>&lt;program&gt; [ -q ] [ -v ] [ -n ]
        version</command></member>
      </simplelist>
    </blockquote>

    <para>The options have the same meanings as when they are passed to
    <filename>/sbin/shorewall</filename> itself. The default VERBOSITY level
    is the level specified in the <filename>shorewall.conf</filename> file
    used when the program was compiled.</para>
  </section>
</article>