shorewall_code/Shorewall6/manpages/shorewall6-conntrack.xml

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<refentry>
  <refmeta>
    <refentrytitle>shorewall6-conntrack</refentrytitle>

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

  <refnamediv>
    <refname>conntrack</refname>

    <refpurpose>shorewall6 conntrack file</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis>
      <command>/etc/shorewall6/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 two different column layouts: FORMAT 1, FORMAT 2,
    and FORMAT 3, 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. The optional '?' was
    introduced in Shorewall 4.5.11 and ?FORMAT is the preferred form; the form
    without the '?' is deprecated.</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 the
    word 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 with only the word COMMENT.</para>

    <note>
      <para>Beginning with Shorewall 4.5.11, ?COMMENT is a synonym for COMMENT
      and is preferred.</para>
    </note>

    <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:notrack</emphasis>|drop}[:<replaceable>chain-designator</replaceable>]</term>

        <listitem>
          <para>This column is only present when FORMAT &gt;= 2. Values other
          than NOTRACK 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.</para>
            </listitem>

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

              <para>Added in Shorewall 4.5.10. Silently discard the
              packet.</para>
            </listitem>

            <listitem>
              <para><option>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.
              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>
          </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="shorewall-exclusion.html">shorewall6-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) ‒
        {-|<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="shorewall-exclusion.html">shorewall-exclusion</ulink>
          (5)).</para>

          <para>COMMENT is only allowed in format 1; the remainder of the line
          is treated as a comment that will be associated with the generated
          rule(s).</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>DEST ‒
        {-|<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="shorewall-exclusion.html">shorewall6-exclusion</ulink>
          (5)).</para>
        </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.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>DEST PORT(S) (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>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>SOURCE PORT(S) (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>
        </listitem>
      </varlistentry>

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

        <listitem>
          <para>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 Shorewall6 4.5.10 and allows enabling and disabling
          the rule without requiring <command>shorewall6
          restart</command>.</para>

          <para>Enables the rule if the value stored in
          <filename>/proc/net/nf_condition/<replaceable>switch-name</replaceable></filename>
          is 1. Disables the rule 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>shorewall6
          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>EXAMPLES</title>

    <para>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            DEST              SOURCE              USER/GROUP
#                                                                                   PORT(S)           PORT(S)
CT:helper:ftp(expevents=new)  fw                -                  tcp              21              </programlisting>

    <para>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            DEST              SOURCE              USER/GROUP
#                                                                                   PORT(S)           PORT(S)
DROP                          all-:2001:1.2.3::4 -
DROP                          all                2001:1.2.3::4
</programlisting>

    <para>or<programlisting>FORMAT 3
#ACTION                       SOURCE             DEST               PROTO            DEST              SOURCE              USER/GROUP
#                                                                                   PORT(S)           PORT(S)
DROP:P                        2001:1.2.3::4      -
DROP:PO                       -                  2001:1.2.3::4
</programlisting></para>
  </refsect1>

  <refsect1>
    <title>FILES</title>

    <para>/etc/shorewall6/notrack</para>
  </refsect1>

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

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

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