shorewall_code/Shorewall/manpages/shorewall-zones.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
"http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd">
<refentry>
  <refmeta>
    <refentrytitle>shorewall-zones</refentrytitle>

    <manvolnum>5</manvolnum>

    <refmiscinfo>Configuration Files</refmiscinfo>
  </refmeta>

  <refnamediv>
    <refname>zones</refname>

    <refpurpose>Shorewall zone declaration file</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis>
      <command>/etc/shorewall/zones</command>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para>The /etc/shorewall/zones file declares your network zones. You
    specify the hosts in each zone through entries in
    <filename>/etc/shorewall/interfaces</filename> or
    <filename>/etc/shorewall/hosts</filename>.</para>

    <para>The columns in the file are as follows (where the column name is
    followed by a different name in parentheses, the different name is used in
    the alternate specification syntax).</para>

    <variablelist>
      <varlistentry>
        <term><emphasis role="bold">ZONE</emphasis> -
        <emphasis>zone</emphasis>[<emphasis
        role="bold">:</emphasis><emphasis>parent-zone</emphasis>[<emphasis
        role="bold">,</emphasis><emphasis>parent-zone</emphasis>]...]</term>

        <listitem>
          <para>Name of the <emphasis>zone</emphasis>. Must start with a
          letter and consist of letters, digits or '_'. The names "all",
          "none", "any", "SOURCE" and "DEST" are reserved and may not be used
          as zone names. The maximum length of a zone name is determined by
          the setting of the LOGFORMAT option in <ulink
          url="shorewall.conf.html">shorewall.conf</ulink>(5). With
          the default LOGFORMAT, zone names can be at most 5 characters
          long.</para>

          <blockquote>
            <para>The maximum length of an iptables log prefix is 29 bytes. As
            explained in <ulink
            url="shorewall.conf.html">shorewall.conf</ulink> (5),
            the legacy default LOGPREFIX formatting string is
            “Shorewall:%s:%s:” where the first %s is replaced by the chain
            name and the second is replaced by the disposition.</para>

            <itemizedlist>
              <listitem>
                <para>The "Shorewall:%s:%s:" formatting string has 12 fixed
                characters ("Shorewall" and three colons).</para>
              </listitem>

              <listitem>
                <para>The longest of the standard dispositions are ACCEPT and
                REJECT which have 6 characters each.</para>
              </listitem>

              <listitem>
                <para>The canonical name for the chain containing the rules
                for traffic going from zone 1 to zone 2 is "&lt;zone
                1&gt;2&lt;zone 2&gt;" or "&lt;zone 1&gt;-&lt;zone
                2&gt;".</para>
              </listitem>

              <listitem>
                <para>So if M is the maximum zone name length, such chains can
                have length 2*M + 1.</para>

                <simplelist>
                  <member>12 + 6 + 2*M + 1 = 29 which reduces to</member>

                  <member>2*M = 29 - 12 - 6 - 1 = 10 or</member>

                  <member>M = 5</member>
                </simplelist>
              </listitem>
            </itemizedlist>

            <para>In Shorewall 5.1.0, the LOGFORMAT in the default and sample
            shorewall.conf files was changed to "%s:%s ".</para>

            <itemizedlist>
              <listitem>
                <para>That formatting string has 2 fixed characters (":" and a
                space).</para>
              </listitem>

              <listitem>
                <para>So the maximum zone name length M is calculated
                as:</para>

                <simplelist>
                  <member>2 + 6 + 2*M + 1 = 29</member>

                  <member>2M = 29 - 2 - 6 - 1 = 20</member>

                  <member>M = 10</member>
                </simplelist>
              </listitem>
            </itemizedlist>
          </blockquote>

          <para>The order in which Shorewall matches addresses from packets to
          zones is determined by the order of zone declarations. Where a zone
          is nested in one or more other zones, you may either ensure that the
          nested zone precedes its parents in this file, or you may follow the
          (sub)zone name by ":" and a comma-separated list of the parent
          zones. The parent zones must have been declared in earlier records
          in this file. See <ulink
          url="shorewall-nesting.html">shorewall-nesting</ulink>(5)
          for additional information.</para>

          <para>Example:</para>

          <programlisting>#ZONE     TYPE     OPTIONS         IN OPTIONS        OUT OPTIONS
a         ip
b         ip
c:a,b     ip</programlisting>

          <para>Currently, Shorewall uses this information to reorder the zone
          list so that parent zones appear after their subzones in the list.
          The IMPLICIT_CONTINUE option in <ulink
          url="shorewall.conf.html">shorewall.conf</ulink>(5) can
          also create implicit CONTINUE policies to/from the subzone.</para>

          <para>Where an <emphasis role="bold">ipsec</emphasis> zone is
          explicitly included as a child of an <emphasis
          role="bold">ip</emphasis> zone, the ruleset allows CONTINUE policies
          (explicit or implicit) to work as expected.</para>

          <para>In the future, Shorewall may make additional use of nesting
          information.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">TYPE</emphasis></term>

        <listitem>
          <variablelist>
            <varlistentry>
              <term><emphasis role="bold">ip</emphasis></term>

              <listitem>
                <para>This is the standard Shorewall zone type and is the
                default if you leave this column empty or if you enter "-" in
                the column. Communication with some zone hosts may be
                encrypted. Encrypted hosts are designated using the 'ipsec'
                option in <ulink
                url="shorewall-hosts.html">shorewall-hosts</ulink>(5).
                For clarity, this zone type may be specified as
                <option>ipv4</option> in IPv4 configurations and
                <option>ipv6</option> in IPv6 configurations.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis role="bold">ipsec</emphasis></term>

              <listitem>
                <para>Communication with all zone hosts is encrypted. Your
                kernel and iptables must include policy match support. For
                clarity, this zone type may be specified as
                <option>ipsec4</option> in IPv4 configurations and
                <option>ipsec6</option> in IPv6 configurations.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis role="bold">firewall</emphasis></term>

              <listitem>
                <para>Designates the firewall itself. You must have exactly
                one 'firewall' zone. No options are permitted with a
                'firewall' zone. The name that you enter in the ZONE column
                will be stored in the shell variable $FW which you may use in
                other configuration files to designate the firewall
                zone.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis role="bold">bport</emphasis></term>

              <listitem>
                <para>The zone is associated with one or more ports on a
                single bridge. For clarity, this zone type may be specified as
                <option>bport4</option> in IPv4 configurations and
                <option>bport6</option> in IPv6 configurations.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis role="bold">vserver</emphasis></term>

              <listitem>
                <para>Added in Shorewall 4.4.11 Beta 2 - A zone composed of
                Linux-vserver guests. The zone contents must be defined in
                <ulink
                url="shorewall-hosts.html">shorewall-hosts</ulink>
                (5).</para>

                <para>Vserver zones are implicitly handled as subzones of the
                firewall zone.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis role="bold">loopback</emphasis></term>

              <listitem>
                <para>Added in Shorewall 4.5.17.</para>

                <para>Normally, Shorewall treats the loopback interface (lo)
                in the following way:</para>

                <itemizedlist>
                  <listitem>
                    <para>By default, all traffic through the interface is
                    ACCEPTed.</para>
                  </listitem>

                  <listitem>
                    <para>If a $FW -&gt; $FW policy is defined or $FW -&gt;
                    $FW rules are defined, they are placed in a chain named
                    ${FW}2${F2} or ${FW}-${FW} (e.g., 'fw2fw' or 'fw-fw' )
                    depending on the ZONE2ZONE setting in <ulink
                    url="shorewall.conf.html">shorewall.conf</ulink>(5).</para>
                  </listitem>

                  <listitem>
                    <para>$FW -&gt; $FW traffic is only filtered in the OUTPUT
                    chain.</para>
                  </listitem>
                </itemizedlist>

                <para>By defining a <emphasis role="bold">loopback</emphasis>
                zone and associating it with the loopback interface in
                shorewall-interfaces(5), you can effect a slightly different
                model. Suppose that the <emphasis
                role="bold">loopback</emphasis> zone name is 'local';
                then:</para>

                <itemizedlist>
                  <listitem>
                    <para>Both $FW -&gt; local and local -&gt; $FW chains are
                    created.</para>
                  </listitem>

                  <listitem>
                    <para>The $FW -&gt; local and local -&gt; $FW policies may
                    be different.</para>
                  </listitem>

                  <listitem>
                    <para>Both $FW -&gt; local and local -&gt; $FW rules may
                    be specified.</para>
                  </listitem>
                </itemizedlist>

                <para>Rules to/from the <emphasis
                role="bold">loopback</emphasis> zone and any zone other than
                the firewall zone are ignored with a warning.</para>

                <para><emphasis role="bold">loopback</emphasis> zones may be
                nested within other <emphasis role="bold">loopback</emphasis>
                zones.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term>local</term>

              <listitem>
                <para>Added in Shorewall 4.5.17. <emphasis
                role="bold">local</emphasis> is the same as <emphasis
                role="bold">ipv4</emphasis> with the exception that the zone
                is only accessible from the <emphasis
                role="bold">firewall</emphasis> and <emphasis
                role="bold">vserver</emphasis> zones.</para>
              </listitem>
            </varlistentry>
          </variablelist>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">OPTIONS, IN OPTIONS and OUT
        OPTIONS</emphasis> (options, in_options, out_options) -
        [<emphasis>option</emphasis>[<emphasis
        role="bold">,</emphasis><emphasis>option</emphasis>]...]</term>

        <listitem>
          <para>A comma-separated list of options. With the exception of the
          <option>mss</option> and <option>blacklist</option> options, these
          only apply to TYPE <option>ipsec</option> zones.</para>

          <variablelist>
            <varlistentry>
              <term><emphasis role="bold">dynamic_shared</emphasis></term>

              <listitem>
                <para>Added in Shorewall 4.5.9. May only be specified in the
                OPTIONS column and indicates that only a single ipset should
                be created for this zone if it has multiple dynamic entries in
                <ulink
                url="shorewall-hosts.html">shorewall-hosts</ulink>(5).
                Without this option, a separate ipset is created for each
                interface.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis
              role="bold">reqid=</emphasis><emphasis>number</emphasis></term>

              <listitem>
                <para>where <emphasis>number</emphasis> is specified using
                setkey(8) using the 'unique:<emphasis>number</emphasis> option
                for the SPD level.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis role="bold">spi=</emphasis>&lt;number&gt;</term>

              <listitem>
                <para>where <emphasis>number</emphasis> is the SPI of the SA
                used to encrypt/decrypt packets.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis role="bold">proto=</emphasis><emphasis
              role="bold">ah</emphasis>|<emphasis
              role="bold">esp</emphasis>|<emphasis
              role="bold">ipcomp</emphasis></term>

              <listitem>
                <para>IPSEC Encapsulation Protocol</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis
              role="bold">mss=</emphasis><emphasis>number</emphasis></term>

              <listitem>
                <para>sets the MSS field in TCP packets. If you supply this
                option, you should also set FASTACCEPT=No in <ulink
                url="shorewall.conf.html">shorewall.conf</ulink>(5)
                to insure that both the SYN and SYN,ACK packets have their MSS
                field adjusted.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis role="bold">mode=</emphasis><emphasis
              role="bold">transport</emphasis>|<emphasis
              role="bold">tunnel</emphasis></term>

              <listitem>
                <para>IPSEC mode</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis
              role="bold">tunnel-src=</emphasis><emphasis>address</emphasis>[/<emphasis>mask</emphasis>]</term>

              <listitem>
                <para>only available with mode=tunnel</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis
              role="bold">tunnel-dst=</emphasis><emphasis>address</emphasis>[/<emphasis>mask</emphasis>]</term>

              <listitem>
                <para>only available with mode=tunnel</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis role="bold">strict</emphasis></term>

              <listitem>
                <para>Means that packets must match all rules.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis role="bold">next</emphasis></term>

              <listitem>
                <para>Separates rules; can only be used with strict</para>
              </listitem>
            </varlistentry>
          </variablelist>

          <para>The options in the OPTIONS column are applied to both incoming
          and outgoing traffic. The IN OPTIONS are applied to incoming traffic
          (in addition to OPTIONS) and the OUT OPTIONS are applied to outgoing
          traffic.</para>

          <para>If you wish to leave a column empty but need to make an entry
          in a following column, use "-".</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>FILES</title>

    <para>/etc/shorewall/zones</para>

    <para>/etc/shorewall6/zones</para>
  </refsect1>

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

    <para><ulink
    url="../Multiple_Zones.html">https://shorewall.org/Multiple_Zones.html</ulink>.</para>

    <para><ulink
    url="../configuration_file_basics.htm#Pairs">https://shorewall.org/configuration_file_basics.htm#Pairs</ulink></para>

    <para>shorewall(8)</para>
  </refsect1>
</refentry>