shorewall_code/Shorewall6/manpages/shorewall6.conf.xml

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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
"http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd">
<refentry>
  <refmeta>
    <refentrytitle>shorewall6.conf</refentrytitle>

    <manvolnum>5</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>shorewall6.conf</refname>

    <refpurpose>Shorewall6 global configuration file</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis>
      <command>/etc/shorewall6/shorewall6.conf</command>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para>This file sets options that apply to Shorewall6 as a whole.</para>

    <para>The file consists of Shell comments (lines beginning with '#'),
    blank lines and assignment statements
    (<emphasis>variable</emphasis>=<emphasis>value</emphasis>). If the
    <emphasis>value</emphasis> contains shell metacharacters or white-space,
    then it must be enclosed in quotes. Example:
    LOG_LEVEL="NFLOG(1,0,1)".</para>
  </refsect1>

  <refsect1>
    <title>OPTIONS</title>

    <para>Many options have as their value a <emphasis>log-level</emphasis>.
    Log levels are a method of describing to syslog (8) the importance of a
    message and a number of parameters in this file have log levels as their
    value.</para>

    <para>These levels are defined by syslog and are used to determine the
    destination of the messages through entries in /etc/syslog.conf (5). The
    syslog documentation refers to these as "priorities"; Netfilter calls them
    "levels" and Shorewall6 also uses that term.</para>

    <para>Valid levels are:</para>

    <programlisting>       7       debug
       6       info
       5       notice
       4       warning
       3       err
       2       crit
       1       alert
       0       emerg</programlisting>

    <para>For most Shorewall6 logging, a level of 6 (info) is appropriate.
    Shorewall6 log messages are generated by NetFilter and are logged using
    facility 'kern' and the level that you specifify. If you are unsure of the
    level to choose, 6 (info) is a safe bet. You may specify levels by name or
    by number.</para>

    <para>If you have built your kernel with NFLOG target support, you may
    also specify a log level of NFLOG (must be all caps). Rather than log its
    messages to syslogd, Shorewall6 will direct netfilter to log the messages
    via the NFLOG target which will send them to a process called 'ulogd'.
    ulogd is available with most Linux distributions (although it probably
    isn't installed by default). Ulogd is also available from <ulink
    url="http://www.netfilter.org/projects/ulogd/index.html">http://www.netfilter.org/projects/ulogd/index.html</ulink>
    and can be configured to log all Shorewall6 message to their own log
    file</para>

    <para>The following options may be set in shorewall6.conf.</para>

    <variablelist>
      <varlistentry>
        <term><emphasis
        role="bold">ACCEPT_DEFAULT=</emphasis>{<emphasis>action</emphasis>[(<replaceable>parameters</replaceable>)][:<replaceable>level</replaceable>]|<emphasis
        role="bold">none</emphasis>}</term>

        <listitem>
          <para></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">DROP_DEFAULT=</emphasis>{<emphasis>action</emphasis>[(<replaceable>parameters</replaceable>)][:<replaceable>level</replaceable>]|<emphasis
        role="bold">none</emphasis>}</term>

        <listitem>
          <para></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">NFQUEUE_DEFAULT=</emphasis>{<emphasis>action</emphasis>[(<replaceable>parameters</replaceable>)][:<replaceable>level</replaceable>]|<emphasis
        role="bold">none</emphasis>}</term>

        <listitem>
          <para></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">QUEUE_DEFAULT=</emphasis>{<emphasis>action</emphasis>[(<replaceable>parameters</replaceable>)][:<replaceable>level</replaceable>]|<emphasis
        role="bold">none</emphasis>}</term>

        <listitem>
          <para></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">REJECT_DEFAULT=</emphasis>{<emphasis>action</emphasis>[(<replaceable>parameters</replaceable>)][:<replaceable>level</replaceable>]|<emphasis
        role="bold">none</emphasis>}</term>

        <listitem>
          <para>DROP_DEFAULT describes the rules to be applied before a
          connection request is dropped by a DROP policy; REJECT_DEFAULT
          describes the rules to be applied if a connection request is
          rejected by a REJECT policy. The other three are similar for ACCEPT,
          QUEUE and NFQUEUE policies.</para>

          <para>The value applied to these may be:</para>

          <simplelist>
            <member>a) The name of an <replaceable>action</replaceable>. The
            name may optionally be followed by a comma-separated list of
            parameters enclosed in parentheses if the specified action accepts
            parameters (e.g., 'Drop(audit)').</member>

            <member>c) <emphasis role="bold">None</emphasis> or <emphasis
            role="bold">none</emphasis></member>
          </simplelist>

          <para>The default values are:</para>

          <simplelist>
            <member>DROP_DEFAULT="Drop"</member>

            <member>REJECT_DEFAULT="Reject"</member>

            <member>ACCEPT_DEFAULT="none"</member>

            <member>QUEUE_DEFAULT="none"</member>

            <member>NFQUEUE_DEFAULT="None"</member>
          </simplelist>

          <para>If you set the value of either option to "None" then no
          default action will be used and the default action or macro must be
          specified in <ulink
          url="shorewall6-policy.html">shorewall6-policy</ulink>(5).</para>

          <para>You can pass <replaceable>parameters</replaceable> to the
          specified action or macro (e.g.,
          <emphasis>myaction(audit,DROP)</emphasis>).</para>

          <para>Beginning with Shorewall 4.5.10, the action name can be
          followed optionally by a colon and a log
          <replaceable>level</replaceable>. The level will be applied to each
          rule in the action or macro body that does not already have a log
          level.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">ACCOUNTING=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>Added in Shorewall 4.4.7. If set to Yes, Shorewall6 accounting
          is enabled (see <ulink
          url="shorewall6-accounting.html">shorewall6-accounting</ulink>(5)).
          If not specified or set to the empty value, ACCOUNTING=Yes is
          assumed.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">ACCOUNTING_TABLE=</emphasis>[<emphasis
        role="bold">filter</emphasis>|<emphasis
        role="bold">mangle</emphasis>]</term>

        <listitem>
          <para>Added in Shorewall 4.4.20. This setting determines which
          Netfilter table the accounting rules are added in. By default,
          ACCOUNTING_TABLE=filter is assumed. See also <ulink
          url="shorewall-accounting.html">shorewall-accounting</ulink>(5).</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">ADMINISABSENTMINDED=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>The value of this variable affects Shorewall6's stopped state.
          When ADMINISABSENTMINDED=No, only traffic to/from those addresses
          listed in <ulink
          url="shorewall6-routestopped.html">shorewall6-routestopped</ulink>(5)
          is accepted when Shorewall6 is stopped. When
          ADMINISABSENTMINDED=Yes, in addition to traffic to/from addresses in
          <ulink
          url="shorewall6-routestopped.html">shorewall6-routestopped</ulink>(5),
          connections that were active when Shorewall6 stopped continue to
          work and all new connections from the firewall system itself are
          allowed. If this variable is not set or is given the empty value
          then ADMINISABSENTMINDED=No is assumed.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">IGNOREUNKNOWNVARIABLES=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>Added in Shorewall 4.5.11. Normally, if an unknown shell
          variable is encountered in a configuration file (except in ?IF and
          ?ELSIF directives), the compiler raises a fatal error. If
          IGNOREUNKNOWNVARIABLES is set to <emphasis
          role="bold">Yes</emphasis>, then such variables simply expand to an
          empty string. Default is <emphasis role="bold">No</emphasis>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">AUTOCOMMENT=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>Formerly named AUTO_COMMENT. If set, if there is not a current
          comment when a macro is invoked, the behavior is as if the first
          line of the macro file was "COMMENT &lt;macro name&gt;". The
          AUTO_COMMENT option has a default value of 'Yes'.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">AUTOHELPERS=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>Added in Shorewall 4.5.7. When set to <option>Yes</option>
          (the default), the generated ruleset will automatically associate
          helpers with applications that require them (FTP, IRC, etc.). When
          configuring your firewall on systems running kernel 3.5 or later, it
          is recommended that you:</para>

          <orderedlist>
            <listitem>
              <para>Set AUTOHELPERS=No.</para>
            </listitem>

            <listitem>
              <para>Either:</para>

              <orderedlist numeration="loweralpha">
                <listitem>
                  <para>Modify <ulink
                  url="shorewall-conntrack.html">shorewall6-conntrack</ulink>
                  (5) to only apply helpers where they are required; or</para>
                </listitem>

                <listitem>
                  <para>Specify the appropriate helper in the HELPER column in
                  <ulink url="shorewall6-rules.html">shorewall6-rules</ulink>
                  (5).</para>

                  <note>
                    <para>The macros for those applications requiring a helper
                    automatically specify the appropriate HELPER where
                    required.</para>
                  </note>
                </listitem>
              </orderedlist>
            </listitem>
          </orderedlist>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">AUTOMAKE=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>If set, the behavior of the <command>start</command> and
          <command>restart</command> commands is change; if no files in
          <filename><filename
          class="directory">/etc/shorewall</filename></filename> have been
          changed since the last successful <command>start</command> or
          <command>restart</command> command, then the compilation step is
          skipped and the compiled script that executed the last
          <command>start</command> or <command>restart</command> command is
          used. The default is AUTOMAKE=No.</para>

          <para>The setting of the AUTOMAKE option is ignored if the
          <command>start</command> or <command>restart</command> command
          includes a directory name (e.g.,<command> shorewall6 restart
          /etc/shorewall.new</command>).</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">BLACKLIST_DISPOSITION=</emphasis>[<emphasis
        role="bold">DROP</emphasis>|A_DROP|<emphasis
        role="bold">REJECT|A_REJECT</emphasis>]</term>

        <listitem>
          <para>This parameter determines the disposition of packets from
          blacklisted hosts. It may have the value DROP if the packets are to
          be dropped or REJECT if the packets are to be replied with an ICMP
          port unreachable reply or a TCP RST (tcp only). If you do not assign
          a value or if you assign an empty value then DROP is assumed. The
          BLACKLIST_DISPOSITION setting has no effect on entries in the
          BLACKLIST section of <ulink
          url="shorewall6-rules.html">shorewall6-rules</ulink> (5). It
          determines the disposition of packets sent to the <emphasis
          role="bold">blacklog</emphasis> target of <ulink
          url="shorewall6-blrules.html">shorewall6-blrules</ulink>(5).</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">BLACKLIST_LOGLEVEL=</emphasis>[<emphasis>log-level</emphasis>]</term>

        <listitem>
          <para>This parameter determines if packets from blacklisted hosts
          are logged and it determines the syslog level that they are to be
          logged at. Its value is a syslog level (Example:
          BLACKLIST_LOGLEVEL=debug). If you do not assign a value or if you
          assign an empty value then packets from blacklisted hosts are not
          logged. The BLACKLIST_LOGLEVEL setting has no effect on entries in
          the BLACKLIST section of <ulink
          url="shorewall6-rules.html">shorewall6-rules</ulink> (5). It
          determines the log level of packets sent to the <emphasis
          role="bold">blacklog</emphasis> target of <ulink
          url="shorewall6-blrules.html">shorewall6-blrules</ulink>(5).</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">BLACKLISTNEWONLY=</emphasis>{<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>}</term>

        <listitem>
          <para>When set to <emphasis role="bold">Yes</emphasis> or <emphasis
          role="bold">yes</emphasis>, blacklists are only consulted for new
          connections. This includes entries in the <ulink
          url="???">shorewall-blrules</ulink> (5) file and in the BLACKLIST
          section of <ulink
          url="shorewall6-rules.html">shorewall6-rules</ulink> (5).</para>

          <para>When set to <emphasis role="bold">No</emphasis> or <emphasis
          role="bold">no</emphasis>, blacklists are consulted for every packet
          (will slow down your firewall noticably if you have large
          blacklists). If the BLACKLISTNEWONLY option is not set or is set to
          the empty value then BLACKLISTNEWONLY=No is assumed.</para>

          <note>
            <para>BLACKLISTNEWONLY=No is incompatible with
            FASTACCEPT=Yes.</para>
          </note>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">CLAMPMSS=[</emphasis><emphasis
        role="bold">Yes</emphasis>|<emphasis
        role="bold">No</emphasis>|<emphasis>value</emphasis>]</term>

        <listitem>
          <para>This parameter enables the TCP Clamp MSS to PMTU feature of
          Netfilter and is usually required when your internet connection is
          through PPPoE or PPTP. If set to <emphasis
          role="bold">Yes</emphasis> or <emphasis role="bold">yes</emphasis>,
          the feature is enabled. If left blank or set to <emphasis
          role="bold">No</emphasis> or <emphasis role="bold">no</emphasis>,
          the feature is not enabled.</para>

          <para><emphasis role="bold">Important</emphasis>: This option
          requires CONFIG_IP_NF_TARGET_TCPMSS in your kernel.</para>

          <para>You may also set CLAMPMSS to a numeric
          <emphasis>value</emphasis> (e.g., CLAMPMSS=1400). This will set the
          MSS field in TCP SYN packets going through the firewall to the
          <emphasis>value</emphasis> that you specify.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">CLEAR_TC=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>If this option is set to <emphasis role="bold">No</emphasis>
          then Shorewall6 won't clear the current traffic control rules during
          [re]start. This setting is intended for use by people that prefer to
          configure traffic shaping when the network interfaces come up rather
          than when the firewall is started. If that is what you want to do,
          set TC_ENABLED=Yes and CLEAR_TC=No and do not supply an
          /etc/shorewall6/tcstart file. That way, your traffic shaping rules
          can still use the “fwmark” classifier based on packet marking
          defined in <ulink
          url="shorewall6-tcrules.html">shorewall6-tcrules</ulink>(5). If not
          specified, CLEAR_TC=No is assumed.</para>

          <warning>
            <para>If you also run Shorewall and if you have
            TC_ENABLED=Internal in your <ulink
            url="../manpages/shorewall.conf.html">shorewall-conf</ulink>(5),
            then you will want CLEAR_TC=No in this file.</para>
          </warning>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">COMPLETE=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>Added in Shorewall6 4.4.12. When you set this option to Yes,
          you are asserting that the configuration is complete so that your
          set of zones encompasses any hosts that can send or receive traffic
          to/from/through the firewall. This causes Shorewall6 to omit the
          rules that catch packets in which the source or destination IP
          address is outside of any of your zones. Default is No. It is
          recommended that this option only be set to Yes if:</para>

          <itemizedlist>
            <listitem>
              <para>You have defined an interface whose effective physical
              setting is '+'.</para>
            </listitem>

            <listitem>
              <para>That interface is assigned to a zone.</para>
            </listitem>

            <listitem>
              <para>You have no CONTINUE policies or rules.</para>
            </listitem>
          </itemizedlist>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">CONFIG_PATH</emphasis>=[<emphasis>directory</emphasis>[:<emphasis>directory</emphasis>]...]</term>

        <listitem>
          <para>Specifies where configuration files other than shorewall6.conf
          may be found. CONFIG_PATH is specifies as a list of directory names
          separated by colons (":"). When looking for a configuration file
          other than shorewall6.conf:</para>

          <itemizedlist>
            <listitem>
              <para>If the command is "try" or a "&lt;configuration
              directory&gt;" was specified in the command (e.g.,
              <command>shorewall6 check ./gateway</command>) then the
              directory given in the command is searched first.</para>
            </listitem>

            <listitem>
              <para>Next, each directory in the CONFIG_PATH setting is
              searched in sequence.</para>
            </listitem>
          </itemizedlist>

          <para>If CONFIG_PATH is not given or if it is set to the empty value
          then the contents of /usr/share/shorewall6/configpath are used. As
          released from shorewall.net, that file sets the CONFIG_PATH to
          /etc/shorewall6:/usr/share/shorewall6:/usr/share/shorewall but your
          particular distribution may set it differently. See the output of
          shorewall6 show config for the default on your system.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">DEFER_DNS_RESOLUTION=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>Added in Shorewall 4.5.12. When set to 'Yes' (the default),
          DNS names are validated in the compiler and then passed on to the
          generated script where they are resolved by ip6tables-restore. This
          is an advantage if you use AUTOMAKE=Yes and the IP address
          associated with the DNS name is subject to change. When
          DEFER_DNS_RESOLUTION=No, DNS names are converted into IP addresses
          by the compiler. This has two advantages:</para>

          <orderedlist>
            <listitem>
              <para>When AUTOMAKE=Yes the <command>start</command> and
              <command>restart</command> commands will succeed even if no DNS
              server is reachable (assuming that the configuration hasn't
              changed since the compiled script was last generated).</para>
            </listitem>

            <listitem>
              <para>The <command>restore</command> command (including the
              automatic <command>restore</command> performed when
              <command>start</command> or <command>restart</command> fails)
              will succeed even if no DNS server is reachable.</para>
            </listitem>
          </orderedlist>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">DELETE_THEN_ADD=</emphasis>{<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>}</term>

        <listitem>
          <para>If set to Yes (the default value), entries in the
          /etc/shorewall6/route_stopped files cause an 'ip rule del' command
          to be generated in addition to an 'ip rule add' command. Setting
          this option to No, causes the 'ip rule del' command to be
          omitted.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">DONT_LOAD=</emphasis>[<emphasis>module</emphasis>[,<emphasis>module</emphasis>]...]</term>

        <listitem>
          <para>Causes Shorewall6 to not load the listed kernel
          modules.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">DYNAMIC_BLACKLIST=</emphasis>{<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>}</term>

        <listitem>
          <para>Added in Shorewall 4.4.7. When set to <emphasis
          role="bold">No</emphasis> or <emphasis role="bold">no</emphasis>,
          dynamic blacklisting using the <command>shorewall6 drop</command>,
          <command>shorewall6 reject</command>, <command>shorewall6
          logdrop</command> and <command>shorewall6 logreject</command> is
          disabled. Default is <emphasis role="bold">Yes</emphasis>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">EXPAND_POLICIES=</emphasis>{<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>}</term>

        <listitem>
          <para>Normally, when the SOURCE or DEST columns in
          shorewall-policy(5) contains 'all', a single policy chain is created
          and the policy is enforced in that chain. For example, if the policy
          entry is<programlisting>#SOURCE DEST POLICY LOG
#                   LEVEL
net     all  DROP   info</programlisting>then the chain name is 'net2all'
          which is also the chain named in Shorewall log messages generated as
          a result of the policy. If EXPAND_POLICIES=Yes, then Shorewall will
          create a separate chain for each pair of zones covered by the
          policy. This makes the resulting log messages easier to interpret
          since the chain in the messages will have a name of the form 'a2b'
          where 'a' is the SOURCE zone and 'b' is the DEST zone.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">EXPORTMODULES=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>Added in Shorewall 4.4.17. When set to Yes when compiling for
          use by Shorewall6 Lite (<command>shorewall6 load</command>,
          <command>shorewall6 reload </command>or <command>shorewall6
          export</command> commands), the compiler will copy the modules or
          helpers file from the administrative system into the script. When
          set to No or not specified, the compiler will not copy the modules
          or helpers file from <filename>/usr/share/shorewall6</filename> but
          will copy the found in another location on the CONFIG_PATH.</para>

          <para>When compiling for direct use by Shorewall6, causes the
          contents of the local module or helpers file to be copied into the
          compiled script. When set to No or not set, the compiled script
          reads the file itself.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">EXPORTPARAMS=</emphasis>{<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>}</term>

        <listitem>
          <para>Deprecated beginning with Shorewall 4.4.17.</para>

          <para>Beginning with Shorewall 4.4.17, the variables set in the
          'params' file at compile time are available at run time with
          EXPORTPARAMS=No. As a consequence, beginning with that version the
          recommended setting is EXPORTPARAMS=No.</para>

          <para>It is quite difficult to code a 'params' file that assigns
          other than constant values such that it works correctly with
          Shorewall6 Lite. The EXPORTPARAMS option works around this problem.
          When EXPORTPARAMS=No, the 'params' file is not copied to the
          compiler output.</para>

          <para>With EXPORTPARAMS=No, if you need to set environmental
          variables on the firewall system for use by your extension scripts,
          then do so in the init extension script.</para>

          <para>The default is EXPORTPARAMS=Yes which is the recommended
          setting unless you are running Shorewall6 Lite.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">FASTACCEPT=</emphasis>{<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>}</term>

        <listitem>
          <para>Normally, Shorewall6 defers accepting ESTABLISHED/RELATED
          packets until these packets reach the chain in which the original
          connection was accepted. So for packets going from the 'loc' zone to
          the 'net' zone, ESTABLISHED/RELATED packets are ACCEPTED in the
          'loc2net' chain.</para>

          <para>If you set FASTACCEPT=Yes, then ESTABLISHED/RELEATED packets
          are accepted early in the INPUT, FORWARD and OUTPUT chains. If you
          set FASTACCEPT=Yes then you may not include rules in the ESTABLISHED
          or RELATED sections of <ulink
          url="shorewall6-rules.html">shorewall6-rules</ulink>(5).</para>

          <note>
            <para>FASTACCEPT=Yes is incompatible with
            BLACKLISTNEWONLY=No.</para>
          </note>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">FORWARD_CLEAR_MARK=</emphasis>{<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>}</term>

        <listitem>
          <para>Added in Shorewall 4.4.11 Beta 3. Traditionally, Shorewall has
          cleared the packet mark in the first rule in the mangle FORWARD
          chain. This behavior is maintained with the default setting of this
          option (FORWARD_CLEAR_MARK=Yes). If FORWARD_CLEAR_MARK is set to
          'No', packet marks set in the mangle PREROUTING chain are retained
          in the FORWARD chains.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">GEOIPDIR</emphasis>=[<emphasis>pathname</emphasis>]</term>

        <listitem>
          <para>Added in Shorewall 4.5.4. Specifies the pathname of the
          directory containing the <firstterm>GeoIP Match</firstterm>
          database. See <ulink
          url="http://www.shorewall.net/ISO-3661.html">http://www.shorewall.net/ISO-3661.html</ulink>.
          If not specified, the default value is
          <filename>/usr/share/xt_geoip/LE</filename> which is the default
          location of the little-endian database.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">HELPERS</emphasis>=[<emphasis>helper</emphasis>[,<replaceable>helper</replaceable>...]]</term>

        <listitem>
          <para>Added in Shorewall 4.5.7. This option lists the Netfilter
          application helps that are to be enabled. If not specified, the
          default is to enable all helpers.</para>

          <para>Possible values for <replaceable>helper</replaceable>
          are:</para>

          <itemizedlist>
            <listitem>
              <para>amanda</para>
            </listitem>

            <listitem>
              <para>ftp</para>
            </listitem>

            <listitem>
              <para>h323</para>
            </listitem>

            <listitem>
              <para>irc</para>
            </listitem>

            <listitem>
              <para>netbios-ns</para>
            </listitem>

            <listitem>
              <para>pptp</para>
            </listitem>

            <listitem>
              <para>sane</para>
            </listitem>

            <listitem>
              <para>sip</para>
            </listitem>

            <listitem>
              <para>snmp</para>
            </listitem>

            <listitem>
              <para>tftp</para>
            </listitem>
          </itemizedlist>

          <para>When HELPERS is specified on a system running Kernel 3.5.0 or
          later, automatic association of helpers to connections is
          disabled.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">HIGH_ROUTE_MARKS=</emphasis>{<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>}</term>

        <listitem>
          <para>Deprecated in Shorewall 4.4.26 in favor of
          PROVIDER_OFFSET.</para>

          <para>You may set HIGH_ROUTE_MARKS=Yes in to effectively divide the
          packet mark and connection mark into two mark fields.</para>

          <para>The width of the fields are determined by the setting of the
          WIDE_TC_MARKS option.</para>

          <para>When WIDE_TC_MARKS=No (the default):</para>

          <orderedlist numeration="loweralpha">
            <listitem>
              <para>The MARK field in the providers file must have a value
              that is less than 65536 and that is a multiple of 256 (using hex
              representation, the values are 0x0100-0xFF00 with the low-order
              8 bits being zero).</para>
            </listitem>

            <listitem>
              <para>You may only set those mark values in the PREROUTING
              chain.</para>
            </listitem>

            <listitem>
              <para>Marks used for traffic shaping must still be in the range
              of 1-255 and may still not be set in the PREROUTING
              chain.</para>
            </listitem>
          </orderedlist>

          <para>When WIDE_TC_MARKS=Yes:</para>

          <orderedlist numeration="loweralpha">
            <listitem>
              <para>The MARK field in the providers file must have a value
              that is a multiple of 65536 (using hex representation, the
              values are 0x010000-0xFF0000 with the low-order 16 bits being
              zero).</para>
            </listitem>

            <listitem>
              <para>You may only set those mark values in the PREROUTING
              chain.</para>
            </listitem>

            <listitem>
              <para>Marks used for traffic shaping must be in the range of
              1-16383 and may still not be set in the PREROUTING chain.</para>
            </listitem>
          </orderedlist>

          <para>Regardless of the setting of WIDE_TC_MARKS, when you SAVE or
          RESTORE in tcrules, only the TC mark value is saved or restored.
          Shorewall handles saving and restoring the routing (provider)
          marks.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">IMPLICIT_CONTINUE=</emphasis>{<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>}</term>

        <listitem>
          <para>When this option is set to <emphasis
          role="bold">Yes</emphasis>, it causes subzones to be treated
          differently with respect to policies.</para>

          <para>Subzones are defined by following their name with ":" and a
          list of parent zones (in <ulink
          url="shorewall6-zones.html">shorewall6-zones</ulink>(5)). Normally,
          you want to have a set of special rules for the subzone and if a
          connection doesn't match any of those subzone-specific rules then
          you want the parent zone rules and policies to be applied; see
          <ulink url="shorewall6-nesting.html">shorewall6-nesting</ulink>(5).
          With IMPLICIT_CONTINUE=Yes, that happens automatically.</para>

          <para>If IMPLICIT_CONTINUE=No or if IMPLICIT_CONTINUE is not set,
          then subzones are not subject to this special treatment. With
          IMPLICIT_CONTINUE=Yes, an implicit CONTINUE policy may be overridden
          by including an explicit policy (one that does not specify "all" in
          either the SOURCE or the DEST columns).</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">IP</emphasis>=[<emphasis>pathname</emphasis>]</term>

        <listitem>
          <para>If specified, gives the pathname of the 'ip' executable. If
          not specified, 'ip' is assumed and the utility will be located using
          the current PATH setting.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">IP_FORWARDING=</emphasis>[<emphasis
        role="bold">On</emphasis>|<emphasis
        role="bold">Off</emphasis>|<emphasis
        role="bold">Keep</emphasis>]</term>

        <listitem>
          <para>This rather useless parameter determines whether Shorewall6
          enables or disables IPV6 Packet Forwarding on all interfaces
          (/proc/sys/net/ipv6/config/all/forwarding). Possible values
          are:</para>

          <variablelist>
            <varlistentry>
              <term><emphasis role="bold">On</emphasis> or <emphasis
              role="bold">on</emphasis></term>

              <listitem>
                <para>packet forwarding will be enabled.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis role="bold">Off</emphasis> or <emphasis
              role="bold">off</emphasis></term>

              <listitem>
                <para>packet forwarding will be disabled.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis role="bold">Keep</emphasis> or <emphasis
              role="bold">keep</emphasis></term>

              <listitem>
                <para>Shorewall6 will neither enable nor disable packet
                forwarding</para>
              </listitem>
            </varlistentry>
          </variablelist>

          <blockquote>
            <para>If this variable is not set or is given an empty value
            (IP_FORWARD="") then IP_FORWARD=On is assumed.</para>
          </blockquote>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">IP6TABLES=</emphasis>[<emphasis>pathname</emphasis>]</term>

        <listitem>
          <para>This parameter names the ip6tables executable to be used by
          Shorewall6. If not specified or if specified as a null value, then
          the ip6tables executable located using the PATH option is
          used.</para>

          <para>Regardless of how the ip6tables utility is located (specified
          via IP6TABLES= or located via PATH), Shorewall6 uses the
          ip6tables-restore and ip6tables-save utilities from that same
          directory.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">IPSET</emphasis>=[<emphasis>pathname</emphasis>]</term>

        <listitem>
          <para>If specified, gives the pathname of the 'ipset' executable. If
          not specified, 'ipset' is assumed and the utility will be located
          using the current PATH setting.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">IPSET_WARNINGS=</emphasis>{<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>}</term>

        <listitem>
          <para>Added in Shorewall 4.5.2. Default is Yes. When set, causes the
          rules compiler to issue a warning when:</para>

          <itemizedlist>
            <listitem>
              <para>The compiler is being run by root and an ipset specified
              in the configuration does not exists. Only one warning is issued
              for each missing ipset.</para>
            </listitem>

            <listitem>
              <para>When [src] is specified in a destination column and when
              [dst] is specified in a source column.</para>
            </listitem>
          </itemizedlist>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">KEEP_RT_TABLES=</emphasis>{<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>}</term>

        <listitem>
          <para>When set to <option>Yes</option>, this option prevents scripts
          generated by Shorewall6 from altering the /etc/iproute2/rt_tables
          database when there are entries in
          <filename>/etc/shorewall6/providers</filename>. If you set this
          option to <option>Yes</option> while Shorewall6 (Shorewall6-lite) is
          running, you should remove the file
          <filename>/var/lib/shorewall6/rt_tables</filename>
          (<filename>/var/lib/shorewall6-lite/rt_tables</filename>) before
          your next <command>stop</command>, <command>refresh</command>,
          <command>restore</command> on <command>restart</command>
          command.</para>

          <para>The default is KEEP_RT_TABLES=No.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">LEGACY_FASTSTART=</emphasis>{<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>}</term>

        <listitem>
          <para>Added in Shorewall6 4.4.20. If not specified, the default is
          Yes which preserves the legacy behavior of <command>start
          -f</command> (the modification times of the files in
          <filename>/etc/shorewall6</filename> are compare with that of
          <filename>/var/lib/shorewall6/restore</filename>). If set to No,
          then the times are compared with that of
          /var/lib/shorewall6/firewall, which is consistant with the way that
          <command>restart -f</command> works.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">LOAD_HELPERS_ONLY=</emphasis>{<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>}</term>

        <listitem>
          <para>Added in Shorewall 4.4.7. When set to Yes, restricts the set
          of modules loaded by shorewall to those listed in
          /var/lib/shorewall6/helpers and those that are actually used. When
          not set, or set to the empty value, LOAD_HELPERS_ONLY=No is
          assumed.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">LOCKFILE</emphasis>=[<emphasis>pathname</emphasis>]</term>

        <listitem>
          <para>Specifies the name of the Shorewall6 lock file, used to
          prevent simultaneous state-changing commands. If not specified,
          ${VARDIR}/shorewall6/lock is assumed (${VARDIR} is normally /var/lib
          but can be changed when Shorewall-core is installed -- see the
          output of <command>shorewall6 show vardir</command>).</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">LOG_VERBOSITY=</emphasis>[<emphasis>number</emphasis>]</term>

        <listitem>
          <para>This option controls the amount of information logged to the
          file specified in the STARTUP_LOG option.</para>

          <para>Values are:</para>

          <simplelist>
            <member>-1 - Logging is disabled</member>

            <member>0 - Silent. Only error messages are logged.</member>

            <member>1 - Major progress messages logged.</member>

            <member>2 - All progress messages logged</member>
          </simplelist>

          <para>If not specified, then -1 is assumed.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">LOGALLNEW=</emphasis>[<emphasis>log-level</emphasis>]</term>

        <listitem>
          <para>This option is intended for use as a debugging aid. When set
          to a log level, this option causes Shorewall6 to generate a logging
          rule as the first rule in each builtin chain.</para>

          <itemizedlist>
            <listitem>
              <para>The table name is used as the chain name in the log
              prefix.</para>
            </listitem>

            <listitem>
              <para>The chain name is used as the target in the log
              prefix.</para>
            </listitem>
          </itemizedlist>

          <para></para>

          <blockquote>
            <para>For example, using the default LOGFORMAT, the log prefix for
            logging from the nat table's PREROUTING chain is:</para>

            <programlisting>    Shorewall:nat:PREROUTING
</programlisting>

            <important>
              <para>To help insure that all packets in the NEW state are
              logged, rate limiting (LOGBURST and LOGRATE) should be disabled
              when using LOGALLNEW. Use LOGALLNEW at your own risk; it may
              cause high CPU and disk utilization and you may not be able to
              control your firewall after you enable this option.</para>
            </important>

            <para></para>

            <caution>
              <para>Do not use this option if the resulting log messages will
              be sent to another system.</para>
            </caution>
          </blockquote>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">LOGFILE=</emphasis>[<emphasis>pathname</emphasis>]</term>

        <listitem>
          <para>This parameter tells the /sbin/shorewall6 program where to
          look for Shorewall6 messages when processing the <emphasis
          role="bold">dump</emphasis>, <emphasis
          role="bold">logwatch</emphasis>, <emphasis role="bold">show
          log</emphasis>, and <emphasis role="bold">hits</emphasis> commands.
          If not assigned or if assigned an empty value, /var/log/messages is
          assumed.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">LOGFORMAT=</emphasis>[<emphasis
        role="bold">"</emphasis><emphasis>formattemplate</emphasis><emphasis
        role="bold">"</emphasis>]</term>

        <listitem>
          <para>The value of this variable generate the --log-prefix setting
          for Shorewall6 logging rules. It contains a “printf” formatting
          template which accepts three arguments (the chain name, logging rule
          number (optional) and the disposition). To use LOGFORMAT with
          fireparse, set it as:</para>

          <programlisting>    LOGFORMAT="fp=%s:%d a=%s "</programlisting>

          <para>If the LOGFORMAT value contains the substring “%d” then the
          logging rule number is calculated and formatted in that position; if
          that substring is not included then the rule number is not included.
          If not supplied or supplied as empty (LOGFORMAT="") then
          “Shorewall6:%s:%s:” is assumed.</para>

          <note>
            <para>The setting of LOGFORMAT has an effect of the permitted
            length of zone names. See <ulink
            url="shorewall6-zones.html">shorewall6-zones</ulink> (5).</para>
          </note>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">LOGLIMIT=[</emphasis>[{<emphasis>s</emphasis>|<emphasis
        role="bold">d</emphasis>}:]<emphasis>rate</emphasis><emphasis
        role="bold">/</emphasis>{<emphasis
        role="bold">sec</emphasis>|<emphasis
        role="bold">min</emphasis>|<emphasis
        role="bold">hour</emphasis>|<emphasis
        role="bold">day</emphasis>}[:<emphasis>burst</emphasis>]]</term>

        <listitem>
          <para>Added in Shorewall 4.4.12. Limits the logging rate, either
          overall, or by source or destination IP address.</para>

          <para>If the value starts with 's:' then logging is limited per
          source IP. If the value starts with 'd:', then logging is limited
          per destination IP. Otherwise, the overall logging rate is
          limited.</para>

          <para>If <replaceable>burst</replaceable> is not specified, then a
          value of 5 is assumed.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">LOGBURST=</emphasis>[<emphasis>burst</emphasis>]</term>

        <listitem>
          <para>Deprecated in Shorewall 4.4.12.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">LOGRATE=</emphasis>[<emphasis>rate</emphasis>/{<emphasis
        role="bold">minute</emphasis>|<emphasis
        role="bold">second</emphasis>}]</term>

        <listitem>
          <para>As of Shorewall 4.4.12, these parameters are
          Deprecated.</para>

          <para>These parameters set the match rate and initial burst size for
          logged packets. Please see ip6tables(8) for a description of the
          behavior of these parameters (the ip6tables option --limit is set by
          LOGRATE and --limit-burst is set by LOGBURST). If both parameters
          are set empty, no rate-limiting will occur. If you supply one of
          these, then you should also supply the other.</para>

          <para>Example:</para>

          <programlisting>    LOGRATE=10/minute
    LOGBURST=5</programlisting>

          <para>For each logging rule, the first time the rule is reached, the
          packet will be logged; in fact, since the burst is 5, the first five
          packets will be logged. After this, it will be 6 seconds (1 minute
          divided by the rate of 10) before a message will be logged from the
          rule, regardless of how many packets reach it. Also, every 6
          seconds, one of the bursts will be regained; if no packets hit the
          rule for 30 seconds, the burst will be fully recharged; back where
          we started.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">LOGTAGONLY=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>Using the default LOGFORMAT, chain names may not exceed 11
          characters or truncation of the log prefix may occur. Longer chain
          names may be used with log tags if you set LOGTAGONLY=Yes. With
          LOGTAGONLY=Yes, if a log tag is specified then the tag is included
          in the log prefix in place of the chain name.</para>

          <para>Beginning with Shorewall 4.5.12, when LOGTAGONLY=Yes, you have
          more control over the generated log prefix. Beginning with that
          release, the tag is interpreted as a <replaceable>chain
          name</replaceable> and a <replaceable>disposition</replaceable>
          separated by a comma. So this rule:</para>

          <programlisting>#ACTION                                SOURCE         DEST
LOG:info:foo,bar                 net                   fw</programlisting>

          <para>would generate the following log prefix when using the default
          LOGFORMAT setting:</para>

          <simplelist>
            <member>Shorewall:foo:bar:</member>
          </simplelist>

          <para>Similarly,</para>

          <programlisting>#ACTION                               SOURCE            DEST
LOG:info:,bar                        net                    fw</programlisting>

          <para>would generate</para>

          <simplelist>
            <member>Shorewall:net2fw:bar:</member>
          </simplelist>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">MACLIST_DISPOSITION=</emphasis>[<emphasis
        role="bold">ACCEPT</emphasis>|<emphasis
        role="bold">DROP</emphasis>|<emphasis
        role="bold">REJECT</emphasis>|A_DROP|A_REJECT]</term>

        <listitem>
          <para>Determines the disposition of connections requests that fail
          MAC Verification and must have the value ACCEPT (accept the
          connection request anyway), REJECT (reject the connection request)
          or DROP (ignore the connection request). If not set or if set to the
          empty value (e.g., MACLIST_DISPOSITION="") then
          MACLIST_DISPOSITION=REJECT is assumed.</para>

          <para>A_DROP and A_REJECT are audited versions of DROP and REJECT
          respectively and were added in Shorewall 4.4.20. They require
          AUDIT_TARGET in the kernel and ip6tables.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">MACLIST_LOG_LEVEL=</emphasis>[<emphasis>log-level</emphasis>]</term>

        <listitem>
          <para>Determines the syslog level for logging connection requests
          that fail MAC Verification. The value must be a valid syslogd log
          level. If you don't want to log these connection requests, set to
          the empty value (e.g., MACLIST_LOG_LEVEL="").</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">MACLIST_TABLE=</emphasis>[<emphasis
        role="bold">filter</emphasis>|<emphasis
        role="bold">mangle</emphasis>]</term>

        <listitem>
          <para>Normally, MAC verification occurs in the filter table (INPUT
          and FORWARD) chains. When forwarding a packet from an interface with
          MAC verification to a bridge interface, that doesn't work.</para>

          <para>This problem can be worked around by setting
          MACLIST_TABLE=mangle which will cause Mac verification to occur out
          of the PREROUTING chain. Because REJECT isn't available in that
          environment, you may not specify MACLIST_DISPOSITION=REJECT with
          MACLIST_TABLE=mangle.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">MACLIST_TTL=[</emphasis><emphasis>number</emphasis>]</term>

        <listitem>
          <para>The performance of configurations with a large numbers of
          entries in <ulink
          url="shorewall-maclist.html">shorewall-maclist</ulink>(5) can be
          improved by setting the MACLIST_TTL variable in <ulink
          url="shorewall.conf.html">shorewall.conf</ulink>(5).</para>

          <para>If your iptables and kernel support the "Recent Match" (see
          the output of "shorewall check" near the top), you can cache the
          results of a 'maclist' file lookup and thus reduce the overhead
          associated with MAC Verification.</para>

          <para>When a new connection arrives from a 'maclist' interface, the
          packet passes through then list of entries for that interface in
          <ulink url="shorewall-maclist.html">shorewall-maclist</ulink>(5). If
          there is a match then the source IP address is added to the 'Recent'
          set for that interface. Subsequent connection attempts from that IP
          address occurring within $MACLIST_TTL seconds will be accepted
          without having to scan all of the entries. After $MACLIST_TTL from
          the first accepted connection request from an IP address, the next
          connection request from that IP address will be checked against the
          entire list.</para>

          <para>If MACLIST_TTL is not specified or is specified as empty (e.g,
          MACLIST_TTL="" or is specified as zero then 'maclist' lookups will
          not be cached).</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">MANGLE_ENABLED=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>Determines whether Shorewall will generate rules in the
          Netfilter mangle table. Setting MANGLE_ENABLED=No disables all
          Shorewall features that require the mangle table. The default is
          MANGLE_ENABLED=Yes.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">MARK_IN_FORWARD_CHAIN=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>If your kernel has a FORWARD chain in the mangle table, you
          may set MARK_IN_FORWARD_CHAIN=Yes to cause the marking specified in
          the tcrules file to occur in that chain rather than in the
          PREROUTING chain. This permits you to mark inbound traffic based on
          its destination address when DNAT is in use. To determine if your
          kernel has a FORWARD chain in the mangle table, use the <emphasis
          role="bold">/sbin/shorewall6 show mangle</emphasis> command; if a
          FORWARD chain is displayed then your kernel will support this
          option. If this option is not specified or if it is given the empty
          value (e.g., MARK_IN_FORWARD_CHAIN="") then MARK_IN_FORWARD_CHAIN=No
          is assumed.</para>
        </listitem>
      </varlistentry>

      <varlistentry id="MASK_BITS">
        <term><emphasis
        role="bold">MASK_BITS</emphasis>=[<replaceable>number</replaceable>]</term>

        <listitem>
          <para>Added in Shorewall 4.4.26. Number of bits on the right of the
          32-bit packet mark to be masked when clearing the traffic shaping
          mark. Must be &gt;= TC_BITS and &lt;= PROVIDER_OFFSET (if
          PROVIDER_OFFSET &gt; 0). Default value and the default values of the
          other mark layout options is determined as follows:</para>

          <table frame="none">
            <title>Default Packet Mark Layout</title>

            <tgroup cols="2">
              <tbody>
                <row>
                  <entry>WIDE_TC_MARKS=No, HIGH_ROUTE_MARKS=No</entry>

                  <entry>TC_BITS=8, PROVIDER_BITS=8, PROVIDER_OFFSET=0,
                  MASK_BITS=8</entry>
                </row>

                <row>
                  <entry>WIDE_TC_MARKS=No, HIGH_ROUTE_MARKS=Yes</entry>

                  <entry>TC_BITS=8, PROVIDER_BITS=8, PROVIDER_OFFSET=8,
                  MASK_BITS=8</entry>
                </row>

                <row>
                  <entry>WIDE_TC_MARKS=Yes, HIGH_ROUTE_MARKS=No</entry>

                  <entry>TC_BITS=14, PROVIDER_BITS=8, PROVIDER_OFFSET=0,
                  MASK_BITS=16</entry>
                </row>

                <row>
                  <entry>WIDE_TC_MARKS=Yes, HIGH_ROUTE_MARKS=Yes</entry>

                  <entry>TC_BITS=14, PROVIDER_BITS=8, PROVIDER_OFFSET=16,
                  MASK_BITS=16</entry>
                </row>
              </tbody>
            </tgroup>
          </table>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">MODULE_SUFFIX=</emphasis>[<emphasis
        role="bold">"</emphasis><emphasis>extension</emphasis> ...<emphasis
        role="bold">"</emphasis>]</term>

        <listitem>
          <para>The value of this option determines the possible file
          extensions of kernel modules. The default value is "ko ko.gz o o.gz
          gz".</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">MODULESDIR=</emphasis>[<emphasis>pathname</emphasis>[<emphasis
        role="bold">:</emphasis><emphasis>pathname</emphasis>]...]</term>

        <listitem>
          <para>This parameter specifies the directory/directories where your
          kernel netfilter modules may be found. If you leave the variable
          empty, Shorewall6 will supply "/lib/modules/`uname
          -r`/kernel/net/ipv4/netfilter:/lib/modules/`uname
          -r`/kernel/net/ipv4/netfilter".</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">MUTEX_TIMEOUT=</emphasis>[<emphasis>seconds</emphasis>]</term>

        <listitem>
          <para>The value of this variable determines the number of seconds
          that programs will wait for exclusive access to the Shorewall6 lock
          file. After the number of seconds corresponding to the value of this
          variable, programs will assume that the last program to hold the
          lock died without releasing the lock.</para>

          <para>If not set or set to the empty value, a value of 60 (60
          seconds) is assumed.</para>

          <para>An appropriate value for this parameter would be twice the
          length of time that it takes your firewall system to process a
          <emphasis role="bold">shorewall6 restart</emphasis> command.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">NFACCT=</emphasis>[<emphasis>pathname</emphasis>]</term>

        <listitem>
          <para>Added in Shorewall 4.5.7. Specifies the pathname of the nfacct
          utiliity. If not specified, Shorewall will use the PATH settting to
          find the program.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">OPTIMIZE=</emphasis>[<replaceable>value</replaceable>]</term>

        <listitem>
          <para>The specified <replaceable>value</replaceable> enables certain
          optimizations. Each optimization category is associated with a power
          of two. To enable multiple optimization categories, simply add their
          corresponding numbers together.</para>

          <itemizedlist>
            <listitem>
              <para>Optimization category 1 - Traditionally, Shorewall has
              created rules for <ulink
              url="../ScalabilityAndPerformance.html">the complete matrix of
              host groups defined by the zones, interfaces and hosts
              files</ulink>. Any traffic that didn't correspond to an element
              of that matrix was rejected in one of the built-in chains. When
              the matrix is sparse, this results in lots of largely useless
              rules.</para>

              <para>These extra rules can be eliminated by setting the 1 bit
              in OPTIMIZE.</para>

              <para>The 1 bit setting also controls the suppression of
              redundant wildcard rules (those specifying "all" in the SOURCE
              or DEST column). A wildcard rule is considered to be redundant
              when it has the same ACTION and Log Level as the applicable
              policy.</para>
            </listitem>

            <listitem>
              <para>Optimization category 2 - Added in Shorewall 4.4.7. When
              set, suppresses superfluous ACCEPT rules in a policy chain that
              implements an ACCEPT policy. Any ACCEPT rules that immediately
              preceed the final blanket ACCEPT rule in the chain are now
              omitted.</para>
            </listitem>

            <listitem>
              <para>Optimization category 4 - Added in Shorewall 4.4.7. When
              set, causes short chains (those with less than 2 rules) to be
              optimized away. The following chains are excluded from
              optimization:</para>

              <itemizedlist>
                <listitem>
                  <para>accounting chains (unless
                  OPTIMIZE_ACCOUNTING=Yes)</para>
                </listitem>

                <listitem>
                  <para>action chains (user-defined)</para>
                </listitem>

                <listitem>
                  <para>'blacklst' chain</para>
                </listitem>

                <listitem>
                  <para>dynamic</para>
                </listitem>
              </itemizedlist>

              <para>Additionally:</para>

              <itemizedlist>
                <listitem>
                  <para>If a built-in chain has a single rule that branches to
                  a second chain, then the rules from the second chain are
                  moved to the built-in chain and the target chain is
                  omitted.</para>
                </listitem>

                <listitem>
                  <para>Chains with no references are deleted.</para>
                </listitem>

                <listitem>
                  <para>Accounting chains are subject to optimization if the
                  OPTIMIZE_ACCOUNTING option is set to 'Yes'.</para>
                </listitem>

                <listitem>
                  <para>If a chain ends with an unconditional branch to a
                  second chain (other than to 'reject'), then the branch is
                  deleted from the first chain and the rules from the second
                  chain are appended to it.</para>
                </listitem>
              </itemizedlist>

              <para>An additional optimization was added in Shorewall 4.5.4.
              If the last rule in a chain is an unqualified jump to a simple
              target, then all immediately preceding rules with the same
              simple target are omitted.</para>

              <para>For example, consider this chain:</para>

              <programlisting>	-A fw-net -p udp --dport 67:68 -j ACCEPT
	-A fw-net -p udp --sport 1194 -j ACCEPT
	-A fw-net -p 41 -j ACCEPT
	-A fw-net -j ACCEPT
</programlisting>

              <para>Since all of the rules are jumps to the simple target
              ACCEPT, this chain is totally optimized away and jumps to the
              chain are replace with jumps to ACCEPT.</para>
            </listitem>

            <listitem>
              <para>Optimization category 8 - Added in Shorewall 4.4.9. When
              set, causes chains with identical rules to be collapsed into a
              single chain.</para>
            </listitem>

            <listitem>
              <para>Optimization category 16 - Added in Shorewall 4.4.26. When
              set, causes sequences of <firstterm>compatible</firstterm> rules
              to be combined into a single rule. Rules are considered
              compatible if they differ only in their destination ports and
              comments.</para>

              <para>A sequence of combatible rules is often generated when
              macros are invoked in sequence.</para>

              <para>The ability to combine adjacent rules is limited by two
              factors:</para>

              <itemizedlist>
                <listitem>
                  <para>Destination port lists may only be combined up to a
                  maximum of 15 ports, where a port-pair counts as two
                  ports.</para>
                </listitem>

                <listitem>
                  <para>Rules may only be combined until the length of their
                  concatinated comment reaches 255 characters.</para>
                </listitem>
              </itemizedlist>

              <para>When either of these limits would be exceeded, the current
              combined rule is emitted and the compiler attemts to combine
              rules beginning with the one that would have exceeded the limit.
              Adjacent combined comments are separated by ', '. Empty comments
              at the front of a group of combined comments are replaced by
              'Others and'. Empty comments at the end of a group of combined
              comments are replaced by 'and others'.</para>

              <para>Beginning in Shorewall 4.5.10, this option also suppresses
              duplicate adjacent rules and duplicate non-adjacent rules that
              don't include <emphasis role="bold">mark</emphasis>, <emphasis
              role="bold">connmark</emphasis>, <emphasis
              role="bold">dscp</emphasis>, <emphasis
              role="bold">ecn</emphasis>, <emphasis
              role="bold">set</emphasis>, <emphasis role="bold">tos</emphasis>
              or <emphasis role="bold">u32</emphasis> matches.</para>

              <variablelist>
                <varlistentry>
                  <term>Example 1:</term>

                  <listitem>
                    <para>Rules with comments "FOO", &lt;empty&gt; and "BAR"
                    would result in the combined comment "FOO and others,
                    BAR".</para>
                  </listitem>
                </varlistentry>

                <varlistentry>
                  <term>Example 2:</term>

                  <listitem>
                    <para>Rules with comments &lt;empty&gt;, "FOO" and "BAR"
                    would reult in the combined comment "Others and FOO, BAR".
                    Note: Optimize level 16 requires "Extended Multi-port
                    Match" in your iptables and kernel.</para>
                  </listitem>
                </varlistentry>
              </variablelist>
            </listitem>
          </itemizedlist>

          <para>The default value is zero which disables all
          optimizations.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">OPTIMIZE_ACCOUNTING=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>Added in Shorewall 4.4.7. If set to Yes, Shorewall accounting
          changes are subject to optimization (OPTIMIZE=4,5,6 or 7). If not
          specified or set to the empty value, OPTIMIZE_ACCOUNTING=No is
          assumed.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">PATH=</emphasis><emphasis>pathname</emphasis>[<emphasis
        role="bold">:</emphasis><emphasis>pathname</emphasis>]...</term>

        <listitem>
          <para>Determines the order in which Shorewall6 searches directories
          for executable files.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">PERL=</emphasis><emphasis>pathname</emphasis></term>

        <listitem>
          <para>Added in Shorewall 4.4.11 RC1. Specifies the path name of the
          Perl executable. Default is <filename>/usr/bin/perl</filename>. If
          the pathname specified by this option does not exist or the named
          file is not executable, then Shorewall6 falls back to
          <filename>/usr/bin/perl/</filename></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">PROVIDER_BITS</emphasis>=[<replaceable>number</replaceable>]</term>

        <listitem>
          <para>Added in Shorewall 4.4.26. The number of bits in the 32-bit
          packet mark to be used for provider numbers. May be zero. See <link
          linkend="MASK_BITS">MASK_BITS</link> above for default value.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">PROVIDER_OFFSET</emphasis>=[<replaceable>number</replaceable>]</term>

        <listitem>
          <para>Added in Shorewall 4.4.26. The offset from the right
          (low-order end) of the provider number field in the 32-bit packet
          mark. If non-zero, must be &gt;= TC_BITS (Shorewall automatically
          adjusts PROVIDER_OFFSET's value). PROVIDER_OFFSET + PROVIDER_BITS +
          ZONE_BITS must be &lt; 32. See <link
          linkend="MASK_BITS">MASK_BITS</link> above for default value.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">RCP_COMMAND="</emphasis><replaceable>command</replaceable><emphasis
        role="bold">"</emphasis></term>

        <listitem>
          <para></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">RSH_COMMAND="</emphasis><replaceable>command</replaceable><emphasis
        role="bold">"</emphasis></term>

        <listitem>
          <para>Eariler generations of Shorewall6 Lite required that remote
          root login via ssh be enabled in order to use the
          <command>load</command> and <command>reload</command> commands.
          Beginning with release 3.9.5, you may define an alternative means
          for accessing the remote firewall system. In that release, two new
          options were added to shorewall6.conf:<simplelist>
              <member>RSH_COMMAND</member>

              <member>RCP_COMMAND</member>
            </simplelist>The default values for these are as
          follows:<simplelist>
              <member>RSH_COMMAND: ssh ${root}@${system} ${command}</member>

              <member>RCP_COMMAND: scp ${files}
              ${root}@${system}:${destination}</member>
            </simplelist>Shell variables that will be set when the commands
          are envoked are as follows:<simplelist>
              <member><replaceable>root</replaceable> - root user. Normally
              <option>root</option> but may be overridden using the '-r'
              option.</member>

              <member><replaceable>system</replaceable> - The name/IP address
              of the remote firewall system.</member>

              <member><replaceable>command</replaceable> - For RSH_COMMAND,
              the command to be executed on the firewall system.</member>

              <member><replaceable>files</replaceable> - For RCP_COMMAND, a
              space-separated list of files to be copied to the remote
              firewall system.</member>

              <member><replaceable>destination</replaceable> - The directory
              on the remote system that the files are to be copied
              into.</member>
            </simplelist></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">RELATED_DISPOSITION=[ACCEPT|A_ACCEPT|A_DROP|A_REJECT|DROP|REJECT]</emphasis></term>

        <listitem>
          <para>Added in Shorewall 4.4.27. Shorewall has traditionally
          ACCEPTed RELATED packets that don't match any rule in the RELATED
          section of <ulink
          url="manpages6/shorewall6-rules.html">shorewall6-rules</ulink> (5).
          Concern about the safety of this practice resulted in the addition
          of this option. When a packet in RELATED state fails to match any
          rule in the RELATED section, the packet is disposed of based on this
          setting. The default value is ACCEPT for compatibility with earlier
          versions.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">RELATED_LOG_LEVEL=</emphasis><emphasis>log-level</emphasis></term>

        <listitem>
          <para>Added in Shorewall 4.4.27. Packets in the related state that
          do not match any rule in the RELATED section of <ulink
          url="manpages/shorewall-rules.html">shorewall6-rules</ulink> (5) are
          logged at this level. The default value is empty which means no
          logging is performed.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">REQUIRE_INTERFACE=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>Added in Shorewall 4.4.10. The default is No. If set to Yes,
          at least one optional interface must be up in order for the firewall
          to be in the started state. Intended to be used with the <ulink
          url="../Manpages/shorewall-init.html">Shorewall Init
          Package</ulink>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">RESTORE_ROUTEMARKS=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>Added in Shorewall 4.5.9. When set to <emphasis
          role="bold">Yes</emphasis> (the default), provider marks are
          restored unconditionally at the top of the mangle OUTPUT and
          PREROUTING chains, even if the saved mark is zero. When this option
          is set to <emphasis role="bold">No</emphasis>, the mark is restored
          even when it is zero. If you have problems with IPSEC ESP packets
          not being routed correctly on output, try setting this option to
          <emphasis role="bold">No</emphasis>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">RESTOREFILE=</emphasis><emphasis>filename</emphasis></term>

        <listitem>
          <para>Specifies the simple name of a file in /var/lib/shorewall6 to
          be used as the default restore script in the <emphasis
          role="bold">shorewall6 save</emphasis>, <emphasis
          role="bold">shorewall6 restore</emphasis>, <emphasis
          role="bold">shorewall6 forget </emphasis>and <emphasis
          role="bold">shorewall6 -f start</emphasis> commands.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">RPFILTER_DISPOSITION=</emphasis>[<emphasis
        role="bold">DROP</emphasis>|<emphasis
        role="bold">REJECT</emphasis>|A_DROP|A_REJECT]</term>

        <listitem>
          <para>Added in Shorewall 4.5.7. Determines the disposition of
          packets entering from interfaces with the <option>rpfilter</option>
          option (see <ulink
          url="shorewall-interfaces.html">shorewall-interfaces</ulink>(5)).
          Packets disposed of by this option are those whose response packets
          would not be sent through the same interface receiving the
          packet.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">RPFILTER_LOG_LEVEL=</emphasis><emphasis>log-level</emphasis></term>

        <listitem>
          <para>Added in shorewall 4.5.7. Determines the logging of packets
          disposed via the RPFILTER_DISPOSITION. The default value is
          <option>info</option>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">SHOREWALL_SHELL=</emphasis>[<emphasis>pathname</emphasis>]</term>

        <listitem>
          <para>This option is used to specify the shell program to be used to
          interpret the compiled script. If not specified or specified as a
          null value, /bin/sh is assumed. Using a light-weight shell such as
          ash or dash can significantly improve performance.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">SMURF_DISPOSITION=</emphasis>[<emphasis
        role="bold">DROP</emphasis>|A_DROP]</term>

        <listitem>
          <para>Added in Shorewall 4.4.20. The default setting is DROP which
          causes smurf packets (see the nosmurfs option in <ulink
          url="shorewall-interfaces.html">shorewall-interfaces</ulink>(5)) to
          be dropped. A_DROP causes the packets to be audited prior to being
          dropped and requires AUDIT_TARGET support in the kernel and
          ip6tables.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">SMURF_LOG_LEVEL=</emphasis>[<emphasis>log-level</emphasis>]</term>

        <listitem>
          <para>Specifies the logging level for smurf packets (see the
          nosmurfs option in <ulink
          url="shorewall6-interfaces.html">shorewall6-interfaces</ulink>(5)).
          If set to the empty value ( SMURF_LOG_LEVEL="" ) then smurfs are not
          logged.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">SFILTER_DISPOSITION=</emphasis>[<emphasis
        role="bold">DROP</emphasis>|<emphasis
        role="bold">REJECT</emphasis>|A_DROP|A_REJECT]</term>

        <listitem>
          <para>Added in Shorewall 4.4.20. Determines the disposition of
          packets matching the <option>sfilter</option> option (see <ulink
          url="shorewall6-interfaces.html">shorewall6-interfaces</ulink>(5))
          and of <firstterm>hairpin</firstterm> packets on interfaces without
          the <option>routeback</option> option.<footnote>
              <para>Hairpin packets are packets that are routed out of the
              same interface that they arrived on.</para>
            </footnote> interfaces without the routeback option.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">SFILTER_LOG_LEVEL=</emphasis><emphasis>log-level</emphasis></term>

        <listitem>
          <para>Added on Shorewall 4.4.20. Determines the logging of packets
          matching the <option>sfilter</option> option (see <ulink
          url="shorewall6-interfaces.html">shorewall6-interfaces</ulink>(5))
          and of <firstterm>hairpin</firstterm> packets on interfaces without
          the <option>routeback</option> option.<footnote>
              <para>Hairpin packets are packets that are routed out of the
              same interface that they arrived on.</para>
            </footnote> interfaces without the routeback option. The default
          is <option>info</option>. If you don't wish for these packets to be
          logged, use SFILTER_LOG_LEVEL=none.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">STARTUP_ENABLED=</emphasis>{<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>}</term>

        <listitem>
          <para>Determines if Shorewall6 is allowed to start. As released from
          shorewall.net, this option is set to <emphasis
          role="bold">No</emphasis>. When set to <emphasis
          role="bold">Yes</emphasis> or <emphasis role="bold">yes</emphasis>,
          Shorewall6 may be started. Used as a guard against Shorewall6 being
          accidentally started before it has been configured.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">STARTUP_LOG=</emphasis>[<emphasis>pathname</emphasis>]</term>

        <listitem>
          <para>If specified, determines where Shorewall6 will log the details
          of each <emphasis role="bold">start</emphasis>, <emphasis
          role="bold">restart</emphasis> and <emphasis
          role="bold">refresh</emphasis> command. Logging verbosity is
          determined by the setting of LOG_VERBOSITY above.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">SUBSYSLOCK=</emphasis>[<emphasis>pathname</emphasis>]</term>

        <listitem>
          <para>This parameter should be set to the name of a file that the
          firewall should create if it starts successfully and remove when it
          stops. Creating and removing this file allows Shorewall6 to work
          with your distribution's initscripts. For RedHat, this should be set
          to /var/lock/subsys/shorewall6. For Debian, the value is
          /var/lock/shorewall6 and in LEAF it is /var/run/shorwall.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">TC</emphasis>=[<emphasis>pathname</emphasis>]</term>

        <listitem>
          <para>If specified, gives the pathname of the 'tc' executable. If
          not specified, 'tc' is assumed and the utility will be located using
          the current PATH setting.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">TC_BITS</emphasis>=[<replaceable>number</replaceable>]</term>

        <listitem>
          <para>Added in Shorewall 4.4.26. The number of bits at the low end
          of the 32-bit packet mark to be used for traffic shaping marking.
          May be zero. See <link linkend="MASK_BITS">MASK_BITS</link> above
          for default value.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">TC_ENABLED=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis
        role="bold">No</emphasis>|<emphasis
        role="bold">Internal|Shared</emphasis>]</term>

        <listitem>
          <para>If you say <emphasis role="bold">Yes</emphasis> or <emphasis
          role="bold">yes</emphasis> here, Shorewall6 will use a script that
          you supply to configure traffic shaping. The script must be named
          'tcstart' and must be placed in a directory on your
          CONFIG_PATH.</para>

          <para>If you say <emphasis role="bold">No</emphasis> or <emphasis
          role="bold">no</emphasis> then traffic shaping is not
          enabled.</para>

          <para>If you set TC_ENABLED=Internal or internal or leave the option
          empty then Shorewall6 will use its builtin traffic shaper
          (tc4shorewall6 written by Arne Bernin.</para>

          <para>Beginning with Shorewall 4.4.15, if you set TC_ENABLED=Shared
          or shared, then you should create symbolic links from your
          Shorewall6 configuration directory (normally
          <filename>/etc/shorewall6/</filename>) to your Shorewall
          <filename>tcdevices</filename> and <filename>tcclasses</filename>
          files. This allows the compiler to have access to your Shorewall
          traffic shaping configuration so that it can validate CLASSIFY rules
          in <ulink url="shorewall-tcrules.html">shorewall6-tcrules</ulink>
          (5).</para>

          <warning>
            <para>If you also run Shorewall and if you have
            TC_ENABLED=Internal in your <ulink
            url="../manpages/shorewall.conf.html">shorewall-conf</ulink>(5),
            then you will want TC_ENABLED=No or TC_ENABLED=Shared in this
            file.</para>
          </warning>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">TC_EXPERT=</emphasis>{<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>}</term>

        <listitem>
          <para>Normally, Shorewall6 tries to protect users from themselves by
          preventing PREROUTING and OUTPUT tcrules from being applied to
          packets that have been marked by the 'track' option in <ulink
          url="shorewall6-providers.html">shorewall6-providers</ulink>(5).</para>

          <para>If you know what you are doing, you can set TC_EXPERT=Yes and
          Shorewall6 will not include these cautionary checks.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">TC_PRIOMAP</emphasis>=<emphasis>map</emphasis></term>

        <listitem>
          <para>Added in Shorewall 4.4.6. Determines the mapping of a packet's
          TOS field to priority bands. See <ulink
          url="shorewall6-tcpri.html">shorewall6-tcpri</ulink>(5). The
          <emphasis>map</emphasis> consists of 16 space-separated digits with
          values 1, 2 or 3. A value of 1 corresponds to Linux priority 0, 2 to
          Linux priority 1, and 3 to Linux Priority 2. The first entry gives
          the priority of TOS value 0, the second of TOS value 1, and so on.
          See tc-prio(8) for additional information.</para>

          <para>The default setting is TC_PRIOMAP="2 3 3 3 2 3 1 1 2 2 2 2 2 2
          2 2".</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">TCP_FLAGS_DISPOSITION=</emphasis>[<emphasis
        role="bold">ACCEPT</emphasis>|<emphasis
        role="bold">DROP</emphasis>|<emphasis
        role="bold">REJECT</emphasis>]</term>

        <listitem>
          <para>Determines the disposition of TCP packets that fail the checks
          enabled by the <emphasis role="bold">tcpflags</emphasis> interface
          option (see <ulink
          url="shorewall6-interfaces.html">shorewall6-interfaces</ulink>(5))
          and must have a value of ACCEPT (accept the packet), REJECT (send an
          RST response) or DROP (ignore the packet). If not set or if set to
          the empty value (e.g., TCP_FLAGS_DISPOSITION="") then
          TCP_FLAGS_DISPOSITION=DROP is assumed.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">TCP_FLAGS_LOG_LEVEL=</emphasis>[<emphasis>log-level</emphasis>]</term>

        <listitem>
          <para>Determines the syslog level for logging packets that fail the
          checks enabled by the tcpflags interface option. The value must be a
          valid syslogd log level. If you don't want to log these packets, set
          to the empty value (e.g., TCP_FLAGS_LOG_LEVEL="").</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">TRACK_PROVIDERS=</emphasis>{<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>}</term>

        <listitem>
          <para>Added in Shorewall 4.4.3. When set to Yes, causes the
          <option>track</option> option to be assumed on all providers defined
          in <ulink
          url="shorewall6-providers.html">shorewall6-providers</ulink>(5). May
          be overridden on an individual provider through use of the
          <option>notrack</option> option. The default value is 'No'.</para>

          <para>Beginning in Shorewall 4.4.6, setting this option to 'Yes'
          also simplifies PREROUTING rules in <ulink
          url="shorewall6-tcrules.html">shorewall6-tcrules</ulink>(5).
          Previously, when TC_EXPERT=No, packets arriving through 'tracked'
          provider interfaces were unconditionally passed to the PREROUTING
          tcrules. This was done so that tcrules could reset the packet mark
          to zero, thus allowing the packet to be routed using the 'main'
          routing table. Using the main table allowed dynamic routes (such as
          those added for VPNs) to be effective. The <ulink
          url="shorewall6-rtrules.html">shorewall6-rtrules</ulink>(5) file was
          created to provide a better alternative to clearing the packet mark.
          As a consequence, passing these packets to PREROUTING complicates
          things without providing any real benefit. Beginning with Shorewall
          4.4.6, when TRACK_PROVIDERS=Yes and TC_EXPERT=No, packets arriving
          through 'tracked' interfaces will not be passed to the PREROUTING
          rules. Since TRACK_PROVIDERS was just introduced in 4.4.3, this
          change should be transparent to most, if not all, users.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">USE_DEFAULT_RT=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>Added in Shorewall6 4.4.25. When set to 'Yes', this option
          causes the Shorewall6 multi-ISP feature to create a different set of
          routing rules which are resilient to changes in the main routing
          table. Such changes can occur for a number of reasons, VPNs going up
          and down being an example. The idea is to send packets through the
          main table prior to applying any of the Shorewall6-generated routing
          rules. So changes to the main table will affect the routing of
          packets by default.</para>

          <para>When USE_DEFAULT_RT=Yes:</para>

          <orderedlist>
            <listitem>
              <para>Both the DUPLICATE and the COPY columns in <ulink
              url="shorewall6-providers.html">shorewall6-providers</ulink>(5)
              file must remain empty (or contain "-").</para>
            </listitem>

            <listitem>
              <para>The default route is added to the the 'default' table
              rather than to the main table.</para>
            </listitem>

            <listitem>
              <para><emphasis role="bold">balance</emphasis> is assumed unless
              <emphasis role="bold">loose</emphasis> is specified.</para>
            </listitem>

            <listitem>
              <para>Packets are sent through the main routing table by a rule
              with priority 999. In <ulink
              url="shorewall6-routing_rules.html">shorewall6-routing_rules</ulink>(5),
              the range 1-998 may be used for inserting rules that bypass the
              main table.</para>
            </listitem>

            <listitem>
              <para>All provider gateways must be specified explicitly in the
              GATEWAY column. <emphasis role="bold">detect</emphasis> may not
              be specified.</para>
            </listitem>

            <listitem>
              <para>You should disable all default route management outside of
              Shorewall6. If a default route is added to the main table while
              Shorewall is started, then all policy routing will stop working
              (except for those routing rules in the priority range
              1-998).</para>
            </listitem>
          </orderedlist>

          <para>If USE_DEFAULT_RT is not set or if it is set to the empty
          string then USE_DEFAULT_RT=No is assumed.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">USE_PHYSICAL_NAMES=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>Added in Shorewall 4.4.27. Normally, when Shorewall creates a
          Netfilter chain that relates to an interface, it uses the
          interfaces's logical name as the base of the chain name. For
          example, if the logical name for an interface is OAKLAND, then the
          input chain for traffic arriving on that interface would be
          'OAKLAND_in'. If this option is set to Yes, then the physical name
          of the interface will be used the base of the chain name.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">VERBOSITY=</emphasis>[<emphasis>number</emphasis>]</term>

        <listitem>
          <para>Shorewall6 has traditionally been very noisy (produced lots of
          output). You may set the default level of verbosity using the
          VERBOSITY OPTION.</para>

          <para>Values are:</para>

          <simplelist>
            <member>0 - Silent. You may make it more verbose using the -v
            option</member>

            <member>1 - Major progress messages displayed</member>

            <member>2 - All progress messages displayed (pre Shorewall6-3.2.0
            behavior)</member>
          </simplelist>

          <para>If not specified, then 2 is assumed.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">WARNOLDCAPVERSION=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>Added in Shorewall 4.5.12. When set to <emphasis
          role="bold">Yes</emphasis> (the default), the compiler issues a
          warning when it finds a capabilities file that doesn't specify all
          of the capabilities supported by the compiler. When
          WARNOLDCAPVERSION is set to <emphasis role="bold">No</emphasis>, no
          warning is issued.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">WIDE_TC_MARKS=</emphasis>{<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>}</term>

        <listitem>
          <para>Deprecated in Shorewall 4.4.26 in favor of TC_BITS and
          MASK_BITS.</para>

          <para>When set to No (the default), traffic shaping marks are 8
          bytes wide (possible values are 1-255). When WIDE_TC_MARKS=Yes,
          traffic shaping marks are 14 bytes wide (values 1-16383). The
          setting of WIDE_TC_MARKS also has an effect on the HIGH_ROUTE_MARKS
          option (see above).</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">ZONE_BITS</emphasis>=[<replaceable>number</replaceable>]</term>

        <listitem>
          <para>Added in Shorewall 4.4.26. When non-zero, enables automatic
          packet marking by source zone and determines the number of bits in
          the 32-bit packet mark to be used for the zone mark. Default value
          is 0.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">ZONE2ZONE</emphasis>={<option>2</option>|<option>-</option>}</term>

        <listitem>
          <para>Added in Shorewall 4.4.4. This option determines how Shorewall
          constructs chain names involving zone names and/or 'all'. The
          default is '2' (e.g., fw2net).</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>FILES</title>

    <para>/etc/shorewall6/shorewall6.conf</para>
  </refsect1>

  <refsect1>
    <title>See ALSO</title>

    <para>shorewall6(8), shorewall6-accounting(5), shorewall6-actions(5),
    shorewall6-blacklist(5), shorewall6-hosts(5), shorewall6-interfaces(5),
    shorewall6-ipsec(5), shorewall6-maclist(5), shorewall6-masq(5),
    shorewall6-nat(5), shorewall6-netmap(5),
    shoewall6-netmap(5),shorewall6-params(5), shorewall6-policy(5),
    shorewall6-providers(5), shorewall6-proxyarp(5), shorewall6-rtrules(5),
    shorewall6-routestopped(5), shorewall6-rules(5), shorewall6-tcclasses(5),
    shorewall6-tcdevices(5), shorewall6-tcrules(5), shorewall6-tos(5),
    shorewall6-tunnels(5), shorewall6-zones(5)</para>
  </refsect1>
</refentry>