shorewall_code/Shorewall/manpages/shorewall-conntrack.xml

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

    <manvolnum>5</manvolnum>

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

  <refnamediv>
    <refname>conntrack</refname>

    <refpurpose>shorewall conntrack file</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis>
      <command>/etc/shorewall[6]/conntrack</command>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para>The original intent of the <emphasis role="bold">notrack</emphasis>
    file was to exempt certain traffic from Netfilter connection tracking.
    Traffic matching entries in the file were not to be tracked.</para>

    <para>The role of the file was expanded in Shorewall 4.4.27 to include all
    rules that can be added in the Netfilter <emphasis
    role="bold">raw</emphasis> table. In 4.5.7, the file's name was changed to
    <emphasis role="bold">conntrack</emphasis>.</para>

    <para>The file supports three different column layouts: FORMAT 1, FORMAT
    2, and FORMAT 3 with FORMAT 1 being the default. The three differ as
    follows:</para>

    <itemizedlist>
      <listitem>
        <para>in FORMAT 2 and 3, there is an additional leading ACTION
        column.</para>
      </listitem>

      <listitem>
        <para>in FORMAT 3, the SOURCE column accepts no zone name; rather the
        ACTION column allows a SUFFIX that determines the chain(s) that the
        generated rule will be added to.</para>
      </listitem>
    </itemizedlist>

    <para>When an entry in the following form is encountered, the format of
    the following entries are assumed to be of the specified
    <replaceable>format</replaceable>.</para>

    <simplelist>
      <member><emphasis role="bold">?FORMAT</emphasis>
      <replaceable>format</replaceable></member>
    </simplelist>

    <para>where <replaceable>format</replaceable> is either <emphasis
    role="bold">1</emphasis>,<emphasis role="bold">2</emphasis> or <emphasis
    role="bold">3</emphasis>.</para>

    <para>Format 3 was introduced in Shorewall 4.5.10.</para>

    <para>Comments may be attached to Netfilter rules generated from entries
    in this file through the use of ?COMMENT lines. These lines begin with
    ?COMMENT; the remainder of the line is treated as a comment which is
    attached to subsequent rules until another ?COMMENT line is found or until
    the end of the file is reached. To stop adding comments to rules, use a
    line containing only ?COMMENT.</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">ACTION</emphasis> - {<emphasis
        role="bold">NOTRACK</emphasis>|<emphasis
        role="bold">CT</emphasis>:<emphasis
        role="bold">helper</emphasis>:<replaceable>name</replaceable>[(<replaceable>arg</replaceable>=<replaceable>val</replaceable>[,...])|<emphasis
        role="bold">CT:ctevents:<replaceable>event</replaceable>[,...]|CT:expevents:new</emphasis><emphasis
        role="bold">|CT:notrack</emphasis>|DROP|LOG|ULOG(<replaceable>ulog-parameters</replaceable>):NFLOG(<replaceable>nflog-parameters</replaceable>)|IPTABLES(<replaceable>target</replaceable>)}[<replaceable>log-level</replaceable>[:<replaceable>log-tag</replaceable>]][:<replaceable>chain-designator</replaceable>]</term>

        <listitem>
          <para>This column is only present when FORMAT &gt;= 2. Values other
          than NOTRACK or DROP require <firstterm>CT Target
          </firstterm>support in your iptables and kernel.</para>

          <itemizedlist>
            <listitem>
              <para><option>NOTRACK</option> or
              <option>CT:notrack</option></para>

              <para>Disables connection tracking for this packet. If a
              <replaceable>log-level</replaceable> is specified, the packet
              will also be logged at that level.</para>
            </listitem>

            <listitem>
              <para><option>CT:helper</option>:<replaceable>name</replaceable></para>

              <para>Attach the helper identified by the
              <replaceable>name</replaceable> to this connection. This is more
              flexible than loading the conntrack helper with preset ports. If
              a <replaceable>log-level</replaceable> is specified, the packet
              will also be logged at that level. Beginning with Shorewall
              4.6.10, the helper name is optional</para>

              <para>At this writing, the available helpers are:</para>

              <variablelist>
                <varlistentry>
                  <term>amanda</term>

                  <listitem>
                    <para>Requires that the amanda netfilter helper is
                    present.</para>
                  </listitem>
                </varlistentry>

                <varlistentry>
                  <term>ftp</term>

                  <listitem>
                    <para>Requires that the FTP netfilter helper is
                    present.</para>
                  </listitem>
                </varlistentry>

                <varlistentry>
                  <term>irc</term>

                  <listitem>
                    <para>Requires that the IRC netfilter helper is
                    present.</para>
                  </listitem>
                </varlistentry>

                <varlistentry>
                  <term>netbios-ns</term>

                  <listitem>
                    <para>Requires that the netbios_ns (sic) helper is
                    present.</para>
                  </listitem>
                </varlistentry>

                <varlistentry>
                  <term>RAS and Q.931</term>

                  <listitem>
                    <para>These require that the H323 netfilter helper is
                    present.</para>
                  </listitem>
                </varlistentry>

                <varlistentry>
                  <term>pptp</term>

                  <listitem>
                    <para>Requires that the pptp netfilter helper is
                    present.</para>
                  </listitem>
                </varlistentry>

                <varlistentry>
                  <term>sane</term>

                  <listitem>
                    <para>Requires that the SANE netfilter helper is
                    present.</para>
                  </listitem>
                </varlistentry>

                <varlistentry>
                  <term>sip</term>

                  <listitem>
                    <para>Requires that the SIP netfilter helper is
                    present.</para>
                  </listitem>
                </varlistentry>

                <varlistentry>
                  <term>snmp</term>

                  <listitem>
                    <para>Requires that the SNMP netfilter helper is
                    present.</para>
                  </listitem>
                </varlistentry>

                <varlistentry>
                  <term>tftp</term>

                  <listitem>
                    <para>Requires that the TFTP netfilter helper is
                    present.</para>
                  </listitem>
                </varlistentry>
              </variablelist>

              <para>May be followed by an option list of
              <replaceable>arg</replaceable>=<replaceable>val</replaceable>
              pairs in parentheses:</para>

              <itemizedlist>
                <listitem>
                  <para><option>ctevents</option>=<replaceable>event</replaceable>[,...]</para>

                  <para>Only generate the specified conntrack events for this
                  connection. Possible event types are: <emphasis
                  role="bold">new</emphasis>, <emphasis
                  role="bold">related</emphasis>, <emphasis
                  role="bold">destroy</emphasis>, <emphasis
                  role="bold">reply</emphasis>, <emphasis
                  role="bold">assured</emphasis>, <emphasis
                  role="bold">protoinfo</emphasis>, <emphasis
                  role="bold">helper</emphasis>, <emphasis
                  role="bold">mark</emphasis> (this is connection mark, not
                  packet mark), <emphasis role="bold">natseqinfo</emphasis>,
                  and <emphasis role="bold">secmark</emphasis>. If more than
                  one <emphasis>event</emphasis> is listed, the
                  <replaceable>event</replaceable> list must be enclosed in
                  parentheses (e.g., ctevents=(new,related)).</para>
                </listitem>

                <listitem>
                  <para><option>expevents</option><option>=new</option></para>

                  <para>Only generate a <emphasis role="bold">new</emphasis>
                  expectation events for this connection.</para>
                </listitem>
              </itemizedlist>
            </listitem>

            <listitem>
              <para>ctevents:<replaceable>event</replaceable>[,...]</para>

              <para>Added in Shorewall 4.6.10. Only generate the specified
              conntrack events for this connection. Possible event types are:
              <emphasis role="bold">new</emphasis>, <emphasis
              role="bold">related</emphasis>, <emphasis
              role="bold">destroy</emphasis>, <emphasis
              role="bold">reply</emphasis>, <emphasis
              role="bold">assured</emphasis>, <emphasis
              role="bold">protoinfo</emphasis>, <emphasis
              role="bold">helper</emphasis>, <emphasis
              role="bold">mark</emphasis> (this is connection mark, not packet
              mark), <emphasis role="bold">natseqinfo</emphasis>, and
              <emphasis role="bold">secmark</emphasis>.</para>
            </listitem>

            <listitem>
              <para>expevents=new</para>

              <para>Added in Shorewall 4.6.10. Only generate <emphasis
              role="bold">new</emphasis> expectation events for this
              connection.</para>
            </listitem>

            <listitem>
              <para><option>DROP</option></para>

              <para>Added in Shorewall 4.5.10. Silently discard the packet. If
              a <replaceable>log-level</replaceable> is specified, the packet
              will also be logged at that level.</para>
            </listitem>

            <listitem>
              <para><option>IPTABLES</option>(<replaceable>target</replaceable>)</para>

              <para>Added in Shorewall 4.6.0. Allows you to specify any
              iptables <replaceable>target</replaceable> with target options
              (e.g., "IPTABLES(AUDIT --type drop)"). If the target is not one
              recognized by Shorewall, the following error message will be
              issued:</para>

              <simplelist>
                <member>ERROR: Unknown target
                (<replaceable>target</replaceable>)</member>
              </simplelist>

              <para>This error message may be eliminated by adding
              <replaceable>target</replaceable> as a builtin action in <ulink
              url="/manpages/shorewall-actions.html">shorewall-actions</ulink>(5).</para>
            </listitem>

            <listitem>
              <para><option>LOG</option></para>

              <para>Added in Shoreawll 4.6.0. Logs the packet using the
              specified <replaceable>log-level</replaceable> and<replaceable>
              log-tag </replaceable>(if any). If no log-level is specified,
              then 'info' is assumed.</para>
            </listitem>

            <listitem>
              <para><option>NFLOG</option></para>

              <para>Added in Shoreawll 4.6.0. Queues the packet to a backend
              logging daemon using the NFLOG netfilter target with the
              specified <replaceable>nflog-parameters</replaceable>.</para>
            </listitem>

            <listitem>
              <para><option>ULOG</option></para>

              <para>IPv4 only. Added in Shoreawll 4.6.0. Queues the packet to
              a backend logging daemon using the ULOG netfilter target with
              the specified <replaceable>ulog-parameters</replaceable>.</para>
            </listitem>
          </itemizedlist>

          <para>When FORMAT = 1, this column is not present and the rule is
          processed as if NOTRACK had been entered in this column.</para>

          <para>Beginning with Shorewall 4.5.10, when FORMAT = 3, this column
          can end with a colon followed by a
          <replaceable>chain-designator</replaceable>. The
          <replaceable>chain-designator</replaceable> can be one of the
          following:</para>

          <variablelist>
            <varlistentry>
              <term>P</term>

              <listitem>
                <para>The rule is added to the raw table PREROUTING chain.
                This is the default if no
                <replaceable>chain-designator</replaceable> is present.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term>O</term>

              <listitem>
                <para>The rule is added to the raw table OUTPUT chain.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term>PO or OP</term>

              <listitem>
                <para>The rule is added to the raw table PREROUTING and OUTPUT
                chains.</para>
              </listitem>
            </varlistentry>
          </variablelist>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>SOURCE (formats 1 and 2) ‒
        {<emphasis>zone</emphasis>[:<emphasis>interface</emphasis>][:<emphasis>address-list</emphasis>]}</term>

        <listitem>
          <para>where <replaceable>zone</replaceable> is the name of a zone,
          <replaceable>interface</replaceable> is an interface to that zone,
          and <replaceable>address-list</replaceable> is a comma-separated
          list of addresses (may contain exclusion - see <ulink
          url="/manpages/shorewall-exclusion.html">shorewall-exclusion</ulink>
          (5)).</para>

          <para>Beginning with Shorewall 4.5.7, <option>all</option> can be
          used as the <replaceable>zone</replaceable> name to mean
          <firstterm>all zones</firstterm>.</para>

          <para>Beginning with Shorewall 4.5.10, <option>all-</option> can be
          used as the <replaceable>zone</replaceable> name to mean all
          <firstterm>off-firewall zone</firstterm>s.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>SOURCE (format 3 prior to Shorewall 5.1.0) ‒
        {-|<emphasis>interface</emphasis>[:<emphasis>address-list</emphasis>]|<replaceable>address-list</replaceable>}</term>

        <listitem>
          <para>Where <replaceable>interface</replaceable> is an interface to
          that zone, and <replaceable>address-list</replaceable> is a
          comma-separated list of addresses (may contain exclusion - see
          <ulink
          url="/manpages/shorewall-exclusion.html">shorewall-exclusion</ulink>
          (5)).</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">SOURCE (format 3 on Shorewall 5.1.0 and
        later) -
        {-|[<replaceable>source-spec</replaceable>[,...]]}</emphasis></term>

        <listitem>
          <para>where <replaceable>source-spec</replaceable> is one of the
          following:</para>

          <variablelist>
            <varlistentry>
              <term><replaceable>interface</replaceable></term>

              <listitem>
                <para>Where interface is the logical name of an interface
                defined in <ulink
                url="shorewall-interfaces.html">shorewall-interface</ulink>(5).</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><replaceable>address</replaceable>[,...][<replaceable>exclusion</replaceable>]</term>

              <listitem>
                <para>where <replaceable>address</replaceable> may be:</para>

                <itemizedlist>
                  <listitem>
                    <para>A host or network IP address.</para>
                  </listitem>

                  <listitem>
                    <para>A MAC address in Shorewall format (preceded by a
                    tilde ("~") and using dash ("-") as a separator.</para>
                  </listitem>

                  <listitem>
                    <para>The name of an ipset preceded by a plus sign ("+").
                    See <ulink
                    url="shorewall-ipsets.html">shorewall-ipsets</ulink>(5).</para>
                  </listitem>
                </itemizedlist>

                <para><replaceable>exclusion</replaceable> is described in
                <ulink
                url="/manpages/shorewall-exclusion.html">shorewall-exclusion</ulink>(5).</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><replaceable>interface</replaceable>:<replaceable>address</replaceable>[,...][<replaceable>exclusion</replaceable>]</term>

              <listitem>
                <para>This form combines the preceding two and requires that
                both the incoming interface and source address match.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><replaceable>exclusion</replaceable></term>

              <listitem>
                <para>See <ulink
                url="/manpages/shorewall-exclusion.html">shorewall-exclusion</ulink>
                (5)</para>
              </listitem>
            </varlistentry>
          </variablelist>

          <para>Beginning with Shorewall 5.1.0, multiple
          <replaceable>source-spec</replaceable>s separated by commas may be
          specified provided that the following alternative forms are
          used:</para>

          <blockquote>
            <para>(<replaceable>address</replaceable>[,...][<replaceable>exclusion</replaceable>])</para>

            <para><replaceable>interface</replaceable>:(<replaceable>address</replaceable>[,...][<replaceable>exclusion</replaceable>])</para>

            <para>(<replaceable>exclusion</replaceable>)</para>
          </blockquote>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>DEST (Prior to Shorewall 5.1.0) ‒
        {-|<emphasis>interface</emphasis>[:<emphasis>address-list</emphasis>]|<replaceable>address-list</replaceable>}</term>

        <listitem>
          <para>where <replaceable>address-list</replaceable> is a
          comma-separated list of addresses (may contain exclusion - see
          <ulink
          url="/manpages/shorewall-exclusion.html">shorewall-exclusion</ulink>
          (5)).</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">DEST (Shorewall 5.1.0 and later) -
        {-|<replaceable>dest-spec</replaceable>[,...]}</emphasis></term>

        <listitem>
          <para>where <replaceable>dest-spec</replaceable> is one of the
          following:</para>

          <variablelist>
            <varlistentry>
              <term><replaceable>interface</replaceable></term>

              <listitem>
                <para>Where interface is the logical name of an interface
                defined in <ulink
                url="shorewall-interfaces.html">shorewall-interface</ulink>(5).</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><replaceable>address</replaceable>[,...][<replaceable>exclusion</replaceable>]</term>

              <listitem>
                <para>where <replaceable>address</replaceable> may be:</para>

                <itemizedlist>
                  <listitem>
                    <para>A host or network IP address.</para>
                  </listitem>

                  <listitem>
                    <para>A MAC address in Shorewall format (preceded by a
                    tilde ("~") and using dash ("-") as a separator.</para>
                  </listitem>

                  <listitem>
                    <para>The name of an ipset preceded by a plus sign ("+").
                    See <ulink
                    url="shorewall-ipsets.html">shorewall-ipsets</ulink>(5).</para>
                  </listitem>
                </itemizedlist>

                <para><replaceable>exclusion</replaceable> is described in
                <ulink
                url="/manpages/shorewall-exclusion.html">shorewall-exclusion</ulink>(5).</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><replaceable>interface</replaceable>:<replaceable>address</replaceable>[,...][<replaceable>exclusion</replaceable>]</term>

              <listitem>
                <para>This form combines the preceding two and requires that
                both the outgoing interface and destination address
                match.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><replaceable>exclusion</replaceable></term>

              <listitem>
                <para>See <ulink
                url="/manpages/shorewall-exclusion.html">shorewall-exclusion</ulink>
                (5)</para>
              </listitem>
            </varlistentry>
          </variablelist>

          <para>Beginning with Shorewall 5.1.0, multiple source-specs
          separated by commas may be specified provided that the following
          alternative forms are used:</para>

          <blockquote>
            <para>(<replaceable>address</replaceable>[,...][<replaceable>exclusion</replaceable>])</para>

            <para><replaceable>interface</replaceable>:(<replaceable>address</replaceable>[,...][<replaceable>exclusion</replaceable>])</para>

            <para>(<replaceable>exclusion</replaceable>)</para>
          </blockquote>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>PROTO ‒
        <replaceable>protocol-name-or-number</replaceable>[,...]</term>

        <listitem>
          <para>A protocol name from <filename>/etc/protocols</filename> or a
          protocol number. tcp and 6 may be optionally followed by <emphasis
          role="bold">:syn </emphasis>to match only the SYN packet (first
          packet in the three-way handshake).</para>

          <para>Beginning with Shorewall 4.5.12, this column can accept a
          comma-separated list of protocols and either <emphasis
          role="bold">proto</emphasis> or <emphasis
          role="bold">protos</emphasis> is accepted in the alternate input
          format.</para>

          <para>Beginning with Shorewall 5.1.11, when <emphasis
          role="bold">tcp</emphasis> or <emphasis role="bold">6</emphasis> is
          specified and the ACTION is <emphasis role="bold">CT</emphasis>, the
          compiler will default to <emphasis role="bold">:syn</emphasis>. If
          you wish the rule to match packets with any valid combination of TCP
          flags, you may specify <emphasis role="bold">tcp:all</emphasis> or
          <emphasis role="bold">6:all</emphasis>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>DPORT - port-number/service-name-list</term>

        <listitem>
          <para>A comma-separated list of port numbers and/or service names
          from <filename>/etc/services</filename>. May also include port
          ranges of the form
          <replaceable>low-port</replaceable>:<replaceable>high-port</replaceable>
          if your kernel and iptables include port range support.</para>

          <para>This column was formerly labelled DEST PORT(S).</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>SPORT - port-number/service-name-list</term>

        <listitem>
          <para>A comma-separated list of port numbers and/or service names
          from <filename>/etc/services</filename>. May also include port
          ranges of the form
          <replaceable>low-port</replaceable>:<replaceable>high-port</replaceable>
          if your kernel and iptables include port range support.</para>

          <para>Beginning with Shorewall 4.5.15, you may place '=' in this
          column, provided that the DPORT column is non-empty. This causes the
          rule to match when either the source port or the destination port in
          a packet matches one of the ports specified in DPORT. Use of '='
          requires multi-port match in your iptables and kernel.</para>

          <para>This column was formerly labelled SOURCE PORT(S).</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>USER ‒
        [<replaceable>user</replaceable>][:<replaceable>group</replaceable>]</term>

        <listitem>
          <para>This column was formerly named USER/GROUP and may only be
          specified if the SOURCE <replaceable>zone</replaceable> is $FW.
          Specifies the effective user id and or group id of the process
          sending the traffic.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">SWITCH -
        [!]<replaceable>switch-name</replaceable>[={0|1}]</emphasis></term>

        <listitem>
          <para>Added in Shorewall 4.5.10 and allows enabling and disabling
          the rule without requiring <command>shorewall
          restart</command>.</para>

          <para>The rule is enabled if the value stored in
          <filename>/proc/net/nf_condition/<replaceable>switch-name</replaceable></filename>
          is 1. The rule is disabled if that file contains 0 (the default). If
          '!' is supplied, the test is inverted such that the rule is enabled
          if the file contains 0.</para>

          <para>Within the <replaceable>switch-name</replaceable>, '@0' and
          '@{0}' are replaced by the name of the chain to which the rule is a
          added. The <replaceable>switch-name</replaceable> (after '...'
          expansion) must begin with a letter and be composed of letters,
          decimal digits, underscores or hyphens. Switch names must be 30
          characters or less in length.</para>

          <para>Switches are normally <emphasis role="bold">off</emphasis>. To
          turn a switch <emphasis role="bold">on</emphasis>:</para>

          <simplelist>
            <member><command>echo 1 &gt;
            /proc/net/nf_condition/<replaceable>switch-name</replaceable></command></member>
          </simplelist>

          <para>To turn it <emphasis role="bold">off</emphasis> again:</para>

          <simplelist>
            <member><command>echo 0 &gt;
            /proc/net/nf_condition/<replaceable>switch-name</replaceable></command></member>
          </simplelist>

          <para>Switch settings are retained over <command>shorewall
          restart</command>.</para>

          <para>When the <replaceable>switch-name</replaceable> is followed by
          <option>=0</option> or <option>=1</option>, then the switch is
          initialized to off or on respectively by the
          <command>start</command> command. Other commands do not affect the
          switch setting.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>EXAMPLE</title>

    <para>IPv4 Example 1:</para>

    <programlisting>#ACTION                       SOURCE            DEST               PROTO            DPORT             SPORT               USER
CT:helper:ftp(expevents=new)  fw                -                  tcp              21              </programlisting>

    <para>IPv4 Example 2 (Shorewall 4.5.10 or later):</para>

    <para>Drop traffic to/from all zones to IP address 1.2.3.4</para>

    <programlisting>?FORMAT 2
#ACTION                       SOURCE             DEST               PROTO           DPORT             SPORT               USER
DROP                          all-:1.2.3.4       -
DROP                          all                1.2.3.4</programlisting>

    <para>or<programlisting>?FORMAT 3
#ACTION                       SOURCE             DEST               PROTO           DPORT             SPORT               USER
DROP:P                        1.2.3.4            -
DROP:PO                       -                  1.2.3.4
</programlisting></para>

    <para>IPv6 Example 1:</para>

    <para>Use the FTP helper for TCP port 21 connections from the firewall
    itself.</para>

    <programlisting>FORMAT 2
#ACTION                       SOURCE            DEST               PROTO            DPORT             SPORT               USER
CT:helper:ftp(expevents=new)  fw                -                  tcp              21              </programlisting>

    <para>IPv6 Example 2 (Shorewall 4.5.10 or later):</para>

    <para>Drop traffic to/from all zones to IP address 2001:1.2.3::4</para>

    <programlisting>FORMAT 2
#ACTION                       SOURCE             DEST               PROTO            DPORT             SPORT               USER
DROP                          all-:2001:1.2.3::4 -
DROP                          all                2001:1.2.3::4
</programlisting>

    <para>or<programlisting>FORMAT 3
#ACTION                       SOURCE             DEST               PROTO            DPORT             SPORT               USER
DROP:P                        2001:1.2.3::4      -
DROP:PO                       -                  2001:1.2.3::4</programlisting></para>
  </refsect1>

  <refsect1>
    <title>FILES</title>

    <para>/etc/shorewall/conntrack</para>

    <para>/etc/shorewall6/conntrack</para>
  </refsect1>

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

    <para><ulink
    url="/configuration_file_basics.htm#Pairs">http://www.shorewall.net/configuration_file_basics.htm#Pairs</ulink></para>

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