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>
  </refmeta>

  <refnamediv>
    <refname>conntrack</refname>

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

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

    <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>}[:<replaceable>chain-designator</replaceable>]</term>

        <listitem>
          <para>This column is only present when FORMAT = 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.</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.</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/>

                  <listitem>
                    <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>
          </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 Shoreall 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>]|COMMENT}</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">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>

          <note>
            <para>In 4.5.10, handling of <option>all</option> was changed.
            <option>all</option> now causes the generated netfilter rule to be
            appended to the raw table PREROUTING and OUTPUT chains directly.
            <option>all-</option> rules are added directly to PREROUTING.
            <option>all</option> and <option>all-</option> rules are processed
            after the more specific rules that specify an individual
            zone.</para>
          </note>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>SOURCE (formats 3) ‒
        {-|[:<emphasis>interface</emphasis>][:<emphasis>address-list</emphasis>}</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 ‒
        [<replaceable>interface</replaceable>|<replaceable>address-list</replaceable>]</term>

        <listitem>
          <para>where <replaceable>interface</replaceable> is the name of a
          network interface 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)). If an interface is given:</para>

          <itemizedlist>
            <listitem>
              <para>It must be up and configured with an IPv4 address when
              Shorewall is started or restarted.</para>
            </listitem>

            <listitem>
              <para>All routes out of the interface must be configured when
              Shorewall is started or restarted.</para>
            </listitem>

            <listitem>
              <para>Default routes out of the interface will result in a
              warning message and will be ignored.</para>
            </listitem>
          </itemizedlist>

          <para>These restrictions are because Netfilter doesn't support
          NOTRACK rules that specify a destination interface (these rules are
          applied before packets are routed and hence the destination
          interface is unknown). Shorewall uses the routes out of the
          interface to replace the interface with an address list
          corresponding to the networks routed out of the named
          interface.</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></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. <replaceable>switch-name</replaceable> 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>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>EXAMPLE</title>

    <para>Example 1:</para>

    <programlisting>#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 1.2.3.4</para>

    <programlisting>FORMAT 2
#ACTION                       SOURCE             DEST               PROTO            DEST              SOURCE              USER/GROUP
#                                                                                   PORT(S)           PORT(S)
DROP                          all-:1.2.3.4       -
DROP                          all                1.2.3.4</programlisting>

    <para>or<programlisting>FORMAT 3
#ACTION                       SOURCE             DEST               PROTO            DEST              SOURCE              USER/GROUP
#                                                                                   PORT(S)           PORT(S)
DROP:P                        1.2.3.4            -
DROP:PO                       -                  1.2.3.4
</programlisting></para>
  </refsect1>

  <refsect1>
    <title>FILES</title>

    <para>/etc/shorewall/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>shorewall(8), shorewall-accounting(5), shorewall-actions(5),
    shorewall-blacklist(5), shorewall-hosts(5), shorewall_interfaces(5),
    shorewall-ipsets(5), shorewall-masq(5), shorewall-nat(5),
    shorewall-netmap(5), shorewall-params(5), shorewall-policy(5),
    shorewall-providers(5), shorewall-proxyarp(5), shorewall-rtrules(5),
    shorewall-routestopped(5), shorewall-rules(5), shorewall.conf(5),
    shorewall-secmarks(5), shorewall-tcclasses(5), shorewall-tcdevices(5),
    shorewall-tcrules(5), shorewall-tos(5), shorewall-tunnels(5),
    shorewall-zones(5)</para>
  </refsect1>
</refentry>