shorewall_code/manpages/shorewall.conf.xml

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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
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<refentry>
  <refmeta>
    <refentrytitle>shorewall.conf</refentrytitle>

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

  <refnamediv>
    <refname>shorewall.conf</refname>

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

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

  <refsect1>
    <title>Description</title>

    <para>This file sets options that apply to Shorewall 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:
    MACLIST_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 Shorewall 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 Shorewall logging, a level of 6 (info) is appropriate.
    Shorewall log messages are generated by NetFilter and are logged using
    facility 'kern' and the level that you specify. 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 ULOG and/or NFLOG target support,
    you may also specify a log level of ULOG and/or NFLOG (must be all caps).
    Rather than log its messages to syslogd, Shorewall will direct netfilter
    to log the messages via the ULOG or 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 Shorewall messages to their own log
    file</para>

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

    <variablelist>
      <varlistentry>
        <term><emphasis
        role="bold">ACCEPT_DEFAULT=</emphasis>{<emphasis>action</emphasis>|<emphasis>macro</emphasis>|<emphasis
        role="bold">none</emphasis>}</term>

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

      <varlistentry>
        <term><emphasis
        role="bold">DROP_DEFAULT=</emphasis>{<emphasis>action</emphasis>|<emphasis>macro</emphasis>|<emphasis
        role="bold">none</emphasis>}</term>

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

      <varlistentry>
        <term><emphasis
        role="bold">REJECT_DEFAULT=</emphasis>{<emphasis>action</emphasis>|<emphasis>macro</emphasis>|<emphasis
        role="bold">none</emphasis>}</term>

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

      <varlistentry>
        <term><emphasis
        role="bold">QUEUE_DEFAULT=</emphasis>{<emphasis>action</emphasis>|<emphasis>macro</emphasis>|<emphasis
        role="bold">none</emphasis>}</term>

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

      <varlistentry>
        <term><emphasis
        role="bold">NFQUEUE_DEFAULT=</emphasis>{<emphasis>action</emphasis>|<emphasis>macro</emphasis>|<emphasis
        role="bold">none</emphasis>}</term>

        <listitem>
          <para>In earlier Shorewall versions, a "default action" for DROP and
          REJECT policies was specified in the file
          /usr/share/shorewall/actions.std.</para>

          <para>To allow for default rules to be applied when USE_ACTIONS=No,
          the DROP_DEFAULT, REJECT_DEFAULT, ACCEPT_DEFAULT, QUEUE_DEFAULT and
          NFQUEUE_DEFAULT options have been added.</para>

          <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>.</member>

            <member>b) <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 USE_ACTIONS=Yes, then these values refer to action.Drop and
          action.Reject respectively. If USE_ACTIONS=No, then these values
          refer to macro.Drop and macro.Reject.</para>

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

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

        <listitem>
          <para>This parameter determines whether Shorewall automatically adds
          the external address(es) in <ulink
          url="shorewall-nat.html">shorewall-nat</ulink>(5). If the variable
          is set to <emphasis role="bold">Yes</emphasis> or <emphasis
          role="bold">yes</emphasis> then Shorewall automatically adds these
          aliases. If it is set to <emphasis role="bold">No</emphasis> or
          <emphasis role="bold">no</emphasis>, you must add these aliases
          yourself using your distribution's network configuration
          tools.</para>

          <para>If this variable is not set or is given an empty value
          (ADD_IP_ALIASES="") then ADD_IP_ALIASES=Yes is assumed.</para>

          <warning>
            <para>Addresses added by ADD_IP_ALIASES=Yes are deleted and
            re-added during shorewall restart. As a consequence, connections
            using those addresses may be severed.</para>
          </warning>
        </listitem>
      </varlistentry>

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

        <listitem>
          <para>This parameter determines whether Shorewall automatically adds
          the SNAT ADDRESS in <ulink
          url="shorewall-masq.html">shorewall-masq</ulink>(5). If the variable
          is set to <emphasis role="bold">Yes</emphasis> or <emphasis
          role="bold">yes</emphasis> then Shorewall automatically adds these
          addresses. If it is set to <emphasis role="bold">No</emphasis> or
          <emphasis role="bold">no</emphasis>, you must add these addresses
          yourself using your distribution's network configuration
          tools.</para>

          <para>If this variable is not set or is given an empty value
          (ADD_SNAT_ALIASES="") then ADD_SNAT_ALIASES=No is assumed.</para>

          <warning>
            <para>Addresses added by ADD_SNAT_ALIASES=Yes are deleted and
            re-added during shorewall restart. As a consequence, connections
            using those addresses may be severed.</para>
          </warning>
        </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 Shorewall's stopped state.
          When ADMINISABSENTMINDED=No, only traffic to/from those addresses
          listed in <ulink
          url="shorewall-routestopped.html">shorewall-routestopped</ulink>(5)
          is accepted when Shorewall is stopped. When ADMINISABSENTMINDED=Yes,
          in addition to traffic to/from addresses in <ulink
          url="shorewall-routestopped.html">shorewall-routestopped</ulink>(5),
          connections that were active when Shorewall 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">AUTO_COMMENT=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>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>

          <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> shorewall restart
          /etc/shorewall.new</command>).</para>
        </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 'start' command is changed; if no
          files in /etc/shorewall 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>
        </listitem>
      </varlistentry>

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

        <listitem>
          <para>Setting this option to 'Yes' allows you to include arbitrarily
          long destination port lists in all configuration files.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis
        role="bold">BLACKLIST_DISPOSITION=</emphasis>[<emphasis
        role="bold">DROP</emphasis>|<emphasis
        role="bold">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.</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.</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. 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 Shorewall won't clear the current traffic control rules during
          [re]start. This setting is intended for use by people who 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/shorewall/tcstart file. That way, your traffic shaping rules
          can still use the “fwmark” classifier based on packet marking
          defined in <ulink
          url="shorewall-tcrules.html">shorewall-tcrules</ulink>(5). If not
          specified, CLEAR_TC=Yes is assumed.</para>
        </listitem>
      </varlistentry>

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

        <listitem>
          <para>Added in Shorewall 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 Shorewall 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 shorewall.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 shorewall.conf:</para>

          <itemizedlist>
            <listitem>
              <para>If the command is "try" or a "&lt;configuration
              directory&gt;" was specified in the command (e.g.,
              <command>shorewall 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>

          <blockquote>
            <para></para>

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

            <para>Note that the setting in /usr/share/shorewall/configpath is
            always used to locate shorewall.conf.</para>
          </blockquote>
        </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/shorewall/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">DETECT_DNAT_IPADDRS=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>If set to <emphasis role="bold">Yes</emphasis> or <emphasis
          role="bold">yes</emphasis>, Shorewall will detect the first IP
          address of the interface to the source zone and will include this
          address in DNAT rules as the original destination IP address. If set
          to <emphasis role="bold">No</emphasis> or <emphasis
          role="bold">no</emphasis>, Shorewall will not detect this address
          and any destination IP address will match the DNAT rule. If not
          specified or empty, “DETECT_DNAT_IPADDRS=Yes” is assumed.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">DISABLE_IPV6=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>If set to <emphasis role="bold">Yes</emphasis> or <emphasis
          role="bold">yes</emphasis>, IPv6 traffic to, from and through the
          firewall system is disabled. If set to <emphasis
          role="bold">No</emphasis> or <emphasis role="bold">no</emphasis>,
          Shorewall will take no action with respect to allowing or
          disallowing IPv6 traffic. If not specified or empty,
          “DISABLE_IPV6=No” is assumed.</para>
        </listitem>
      </varlistentry>

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

        <listitem>
          <para>Causes Shorewall 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>shorewall drop</command>,
          <command>shorewall reject</command>, <command>shorewall
          logdrop</command> and <command>shorewall 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">EXPORTPARAMS=</emphasis>{<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>}</term>

        <listitem>
          <para>It is quite difficult to code a 'params' file that assigns
          other than constant values such that it works correctly with
          Shorewall 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 using Shorewall 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, Shorewall 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="shorewall-rules.html">shorewall-rules</ulink>(5).</para>

          <para></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 (CLEAR_FORWARD_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">HIGH_ROUTE_MARKS=</emphasis>{<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>}</term>

        <listitem>
          <para>Prior to version 3.2.0, it was not possible to use connection
          marking in <ulink
          url="shorewall-tcrules.html">shorewall-tcrules</ulink>(5) if you had
          a multi-ISP configuration that uses the track option.</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
          WIDE_TC_MARKS. If 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="shorewall-zones.html">shorewall-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="shorewall-nesting.html">shorewall-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 parameter determines whether Shorewall enables or
          disables IPV4 Packet Forwarding (/proc/sys/net/ipv4/ip_forward).
          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>Shorewall will neither enable nor disable packet
                forwarding.</para>
              </listitem>
            </varlistentry>
          </variablelist>

          <para></para>

          <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">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">IPTABLES=</emphasis>[<emphasis>pathname</emphasis>]</term>

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

          <para>Regardless of how the IPTABLES utility is located (specified
          via IPTABLES= or located via PATH), Shorewall uses the
          iptables-restore and iptables-save utilities from that same
          directory.</para>
        </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
          generated scripts from altering the /etc/iproute2/rt_tables database
          when there are entries in
          <filename>/etc/shorewall/providers</filename>. If you set this
          option to <option>Yes</option> while Shorewall (Shorewall-lite) is
          running, you should remove the file
          <filename>/var/lib/shorewall/rt_tables</filename>
          (<filename>/var/lib/shorewall-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">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/shorewall/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">LOG_MARTIANS=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis
        role="bold">No</emphasis>|Keep]</term>

        <listitem>
          <para>If set to <emphasis role="bold">Yes</emphasis> or <emphasis
          role="bold">yes</emphasis>, sets
          <filename>/proc/sys/net/ipv4/conf/*/log_martians</filename> to 1
          with the exception of
          <filename>/proc/sys/net/ipv4/conf/all/log_martians which is set to
          0</filename>. The default value is <emphasis
          role="bold">Yes</emphasis> which sets both of the above to one. If
          you do not enable martian logging for all interfaces, you may still
          enable it for individual interfaces using the <emphasis
          role="bold">logmartians</emphasis> interface option in <ulink
          url="shorewall-interfaces.html">shorewall-interfaces</ulink>(5).</para>

          <para>The value <emphasis role="bold">Keep</emphasis> causes
          Shorewall to ignore the option. If the option is set to <emphasis
          role="bold">Yes</emphasis>, then martians are logged on all
          interfaces. If the option is set to <emphasis
          role="bold">No</emphasis>, then martian logging is disabled on all
          interfaces except those specified in <ulink
          url="shorewall-interfaces.html">shorewall-interfaces</ulink>(5).</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 Shorewall 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/shorewall program where to look
          for Shorewall 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. For further information, see <ulink
          url="http://www.shorewall.net/shorewall_logging.html">http://www.shorewall.net/shorewall_logging.html</ulink>.</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 Shorewall 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
          “Shorewall:%s:%s:” is assumed.</para>
        </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></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>Deprecated in Shorewall 4.4.12. These options are ignored when
          LOGLIMIT is specified.</para>

          <para>These parameters set the match rate and initial burst size for
          logged packets. Please see iptables(8) for a description of the
          behavior of these parameters (the iptables 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>
        </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>]</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>
        </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">MAPOLDACTIONS=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>This option is included for compatibility with old Shorewall
          configuration. New installs should always have
          MAPOLDACTIONS=No.</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/shorewall 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>
        <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 "o gz ko
          o.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, Shorewall will supply the value "/lib/modules/`uname
          -r`/kernel/net/ipv4/netfilter" in versions of Shorewall prior to
          3.2.4 and "/lib/modules/`uname
          -r`/kernel/net/ipv4/netfilter:/lib/modules/`uname
          -r`/kernel/net/ipv4/netfilter" in later versions.</para>
        </listitem>
      </varlistentry>

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

        <listitem>
          <para>This option will normally be set to 'No' (the default). It
          should be set to 'Yes' under the following circumstances:</para>

          <orderedlist>
            <listitem>
              <para>You have an interface that has parallel zones defined via
              /etc/shorewall/hosts.</para>
            </listitem>

            <listitem>
              <para>You want to forward multicast packets to two or more of
              those parallel zones.</para>
            </listitem>
          </orderedlist>

          <para>In such cases, you will configure a <option>destonly</option>
          network on each zone receiving multicasts.</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 Shorewall 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">shorewall restart</emphasis> command.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">NULL_ROUTE_RFC1918=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>]</term>

        <listitem>
          <para>When set to Yes, causes Shorewall to null-route the IPv4
          address ranges reserved by RFC1918. The default value is
          'No'.</para>

          <para>When combined with route filtering (ROUTE_FILTER=Yes or
          <option>routefilter</option> in <ulink
          url="shorewall-interfaces.html">shorewall-interfaces</ulink>(5)),
          this option ensures that packets with an RFC1918 source address are
          only accepted from interfaces having known routes to networks using
          such addresses.</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>

                <listitem>
                  <para>forwardUPnP</para>
                </listitem>

                <listitem>
                  <para>UPnP (nat table)</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>
            </listitem>

            <listitem>
              <para>Optimization category 8 - Added in Shorewall 4.4.9. When
              set, causes chains with duplicate rules to be collapsed into a
              single chain.</para>
            </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 Shorewall 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 Shorewall falls back to
          <filename>/usr/bin/perl/</filename></para>
        </listitem>
      </varlistentry>

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

        <listitem>
          <para>This option is included for compatibility with older Shorewall
          releases. Its setting has no effect.</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 Shorewall 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 shorewall.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">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="shorewall-init.html">Shorewall Init Package</ulink>.</para>
        </listitem>
      </varlistentry>

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

        <listitem>
          <para>This option determines whether to restore the default route
          saved when here are 'balance' providers defined but all of them are
          down.</para>

          <para>The default is RESTORE_DEFAULT_ROUTE=Yes which preserves the
          pre-4.2.6 behavior.</para>

          <para>RESTORE_DEFAULT_ROUTE=No is appropriate when you don't want a
          default route in the main table (USE_DEFAULT_RT=No) or in the
          default table (USE_DEFAULT_RT=Yes) when there are no balance
          providers available. In that case, RESTORE_DEFAULT_ROUTE=No will
          cause any default route in the relevant table to be deleted.</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/shorewall to
          be used as the default restore script in the <emphasis
          role="bold">shorewall save</emphasis>, <emphasis
          role="bold">shorewall restore</emphasis>, <emphasis
          role="bold">shorewall forget </emphasis>and <emphasis
          role="bold">shorewall -f start</emphasis> commands.</para>
        </listitem>
      </varlistentry>

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

        <listitem>
          <para>During <emphasis role="bold">shorewall star</emphasis>t, IP
          addresses to be added as a consequence of ADD_IP_ALIASES=Yes and
          ADD_SNAT_ALIASES=Yes are quietly deleted when <ulink
          url="shorewall-nat.html">shorewall-nat</ulink>(5) and <ulink
          url="shorewall-masq.html">shorewall-masq</ulink>(5) are processed
          then are re-added later. This is done to help ensure that the
          addresses can be added with the specified labels but can have the
          undesirable side effect of causing routes to be quietly deleted.
          When RETAIN_ALIASES is set to Yes, existing addresses will not be
          deleted. Regardless of the setting of RETAIN_ALIASES, addresses
          added during <emphasis role="bold">shorewall start</emphasis> are
          still deleted at a subsequent <emphasis role="bold">shorewall
          stop</emphasis> or <emphasis role="bold">shorewall
          restart</emphasis>.</para>
        </listitem>
      </varlistentry>

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

        <listitem>
          <para>If this parameter is given the value <emphasis
          role="bold">Yes</emphasis> or <emphasis role="bold">yes</emphasis>
          then route filtering (anti-spoofing) is enabled on all network
          interfaces which are brought up while Shorewall is in the started
          state. The default value is <emphasis
          role="bold">no</emphasis>.</para>

          <para>The value <emphasis role="bold">Keep</emphasis> causes
          Shorewall to ignore the option. If the option is set to <emphasis
          role="bold">Yes</emphasis>, then route filtering occurs on all
          interfaces. If the option is set to <emphasis
          role="bold">No</emphasis>, then route filtering is disabled on all
          interfaces except those specified in <ulink
          url="shorewall-interfaces.html">shorewall-interfaces</ulink>(5).</para>
        </listitem>
      </varlistentry>

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

        <listitem>
          <para>Re-enabled in Shorewall 4.4.6. If SAVE_IPSETS=Yes, then the
          current contents of your ipsets will be saved by the <emphasis
          role="bold">shorewall stop</emphasis> and <emphasis
          role="bold">shorewall save</emphasis> commands and restored by the
          <emphasis role="bold">shorewall start</emphasis> and <emphasis
          role="bold">shorewall restore</emphasis> commands.</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
          run the Shorewall compiler and 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_LOG_LEVEL=</emphasis>[<emphasis>log-level</emphasis>]</term>

        <listitem>
          <para>Specifies the logging level for smurf packets (see the
          nosmurfs option in <ulink
          url="shorewall-interfaces.html">shorewall-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">STARTUP_ENABLED=</emphasis>{<emphasis
        role="bold">Yes</emphasis>|<emphasis role="bold">No</emphasis>}</term>

        <listitem>
          <para>Determines if Shorewall 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>,
          Shorewall may be started. Used as a guard against Shorewall 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 Shorewall 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 Shorewall to work with
          your distribution's initscripts. For RedHat and OpenSuSE, this
          should be set to /var/lock/subsys/shorewall. For Debian, the value
          is /var/lock/shorewall 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_ENABLED=</emphasis>[<emphasis
        role="bold">Yes</emphasis>|<emphasis
        role="bold">No</emphasis>|<emphasis
        role="bold">Internal</emphasis>|<emphasis
        role="bold">Simple</emphasis>]</term>

        <listitem>
          <para>If you say <emphasis role="bold">Yes</emphasis> or <emphasis
          role="bold">yes</emphasis> here, Shorewall 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=Simple (Shorewall 4.4.6 and later),
          simple traffic shaping using <ulink
          url="shorewall-tcinterfaces.html">shorewall-tcinterfaces</ulink>(5)
          and <ulink url="shorewall-tcpri.html">shorewall-tcpri</ulink>(5) is
          enabled.</para>

          <para>If you set TC_ENABLED=Internal or internal or leave the option
          empty then Shorewall will use its builtin traffic shaper
          (tc4shorewall written by Arne Bernin.</para>
        </listitem>
      </varlistentry>

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

        <listitem>
          <para>Normally, Shorewall 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="shorewall-providers.html">shorewall-providers</ulink>(5).</para>

          <para>If you know what you are doing, you can set TC_EXPERT=Yes and
          Shorewall 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="shorewall-tcpri.html">shorewall-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="shorewall-interfaces.html">shorewall-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="shorewall-providers.html">shorewall-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="shorewall-tcrules.html">shorewall-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 route_rules 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>When set to 'Yes', this option causes the Shorewall 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 Shorewall-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="shorewall-providers.html">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="shorewall-routing_rules.html">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.<note>
                  <para><emphasis role="bold">detect</emphasis> may be
                  specified for interfaces whose configuration is managed by
                  dhcpcd. Shorewall will use dhcpcd's database to find the
                  interfaces's gateway.</para>
                </note></para>
            </listitem>

            <listitem>
              <para>You should disable all default route management outside of
              Shorewall. 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">VERBOSITY=</emphasis>[<emphasis>number</emphasis>]</term>

        <listitem>
          <para>Shorewall 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 Shorewall-3.2.0
            behavior)</member>
          </simplelist>

          <para>If not specified, then 2 is assumed.</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>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">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/shorewall/shorewall.conf</para>
  </refsect1>

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

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