shorewall_code/Shorewall/manpages/shorewall-tcrules.xml

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<refentry>
  <refmeta>
    <refentrytitle>shorewall-tcrules</refentrytitle>

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

  <refnamediv>
    <refname>tcrules</refname>

    <refpurpose>Shorewall Packet Marking rules file</refpurpose>
  </refnamediv>

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

  <refsect1>
    <title>Description</title>

    <para>Entries in this file cause packets to be marked as a means of
    classifying them for traffic control or policy routing.</para>

    <important>
      <para>Unlike rules in the <ulink
      url="shorewall-rules.html">shorewall-rules</ulink>(5) file, evaluation
      of rules in this file will continue after a match. So the final mark for
      each packet will be the one assigned by the LAST tcrule that
      matches.</para>

      <para>If you use multiple internet providers with the 'track' option, in
      /etc/shorewall/providers be sure to read the restrictions at <ulink
      url="http://shorewall.net/MultiISP.html">http://shorewall.net/MultiISP.html</ulink>.</para>
    </important>

    <para>Beginning with Shorewall 4.5.4, the tcrules file supports two
    different formats:</para>

    <variablelist>
      <varlistentry>
        <term>FORMAT 1 (default - deprecated)</term>

        <listitem>
          <para>The older limited-function version of TPROXY is
          supported.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>FORMAT 2</term>

        <listitem>
          <para>The newer version of TPROXY is supported.</para>
        </listitem>
      </varlistentry>
    </variablelist>

    <para>The format is specified by a line as follows:</para>

    <blockquote>
      <para><emphasis role="bold">[?]FORMAT {1|2}</emphasis></para>
    </blockquote>

    <para>The optional '?' was introduced in Shorewall 4.5.11 and ?FORMAT is
    the preferred form; the form without the '?' is deprecated.</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> (mark) -
        <replaceable>mark</replaceable></term>

        <listitem>
          <para>Where <replaceable>mark</replaceable> may assume one of the
          following values.</para>

          <orderedlist numeration="arabic">
            <listitem>
              <para>A mark <emphasis>value</emphasis> which is an integer in
              the range 1-255.</para>

              <para>Normally will set the mark value. If preceded by a
              vertical bar ("|"), the mark value will be logically ORed with
              the current mark value to produce a new mark value. If preceded
              by an ampersand ("&amp;"), will be logically ANDed with the
              current mark value to produce a new mark value.</para>

              <para>Both "|" and "&amp;" require Extended MARK Target support
              in your kernel and iptables; neither may be used with connection
              marks (see below).</para>

              <para>May optionally be followed by <emphasis
              role="bold">:P</emphasis>, <emphasis
              role="bold">:F</emphasis>,<emphasis role="bold">:T</emphasis> or
              <emphasis role="bold">:I</emphasis> where<emphasis role="bold">
              :P</emphasis> indicates that marking should occur in the
              PREROUTING chain, <emphasis role="bold">:F</emphasis> indicates
              that marking should occur in the FORWARD chain, <emphasis
              role="bold">:I </emphasis>indicates that marking should occur in
              the INPUT chain (added in Shorewall 4.4.13), and <emphasis
              role="bold">:T</emphasis> indicates that marking should occur in
              the POSTROUTING chain. If neither <emphasis
              role="bold">:P</emphasis>, <emphasis role="bold">:F</emphasis>
              nor <emphasis role="bold">:T</emphasis> follow the mark value
              then the chain is determined as follows:</para>

              <para>- If the SOURCE is <emphasis
              role="bold">$FW</emphasis>[<emphasis
              role="bold">:</emphasis><emphasis>address-or-range</emphasis>[,<emphasis>address-or-range</emphasis>]...],
              then the rule is inserted into the OUTPUT chain. When
              HIGH_ROUTE_MARKS=Yes, only high mark values may be assigned
              there. Packet marking rules for traffic shaping of packets
              originating on the firewall must be coded in the POSTROUTING
              chain (see below).</para>

              <para>- Otherwise, the chain is determined by the setting of
              MARK_IN_FORWARD_CHAIN in <ulink
              url="shorewall.conf.html">shorewall.conf</ulink>(5).</para>

              <para>Please note that <emphasis role="bold">:I</emphasis> is
              included for completeness and affects neither traffic shaping
              nor policy routing.</para>

              <para>If your kernel and iptables include CONNMARK support then
              you can also mark the connection rather than the packet.</para>

              <para>The mark value may be optionally followed by "/" and a
              mask value (used to determine those bits of the connection mark
              to actually be set). When a mask is specified, the result of
              logically ANDing the mark value with the mask must be the same
              as the mark value.</para>

              <para>The mark and optional mask are then followed by one
              of:</para>

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

                  <listitem>
                    <para>Mark the connection in the chain determined by the
                    setting of MARK_IN_FORWARD_CHAIN</para>
                  </listitem>
                </varlistentry>

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

                  <listitem>
                    <para>Mark the connection in the FORWARD chain</para>
                  </listitem>
                </varlistentry>

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

                  <listitem>
                    <para>Mark the connection in the PREROUTING chain.</para>
                  </listitem>
                </varlistentry>

                <varlistentry>
                  <term>CT</term>

                  <listitem>
                    <para>Mark the connection in the POSTROUTING chain</para>
                  </listitem>
                </varlistentry>

                <varlistentry>
                  <term>CI</term>

                  <listitem>
                    <para>Mark the connection in the INPUT chain. This option
                    is included for completeness and has no applicability to
                    traffic shaping or policy routing.</para>
                  </listitem>
                </varlistentry>
              </variablelist>
            </listitem>

            <listitem>
              <para>A mark range which is a pair of integers separated by a
              dash ("-"). Added in Shorewall 4.5.9.</para>

              <para>May be optionally followed by a slash ("/") and a mask and
              requires the <firstterm>Statistics Match</firstterm> capability
              in iptables and kernel. Marks in the specified range are
              assigned to packets on a round-robin fashion.</para>

              <para>When a mask is specified, the result of logically ANDing
              each mark value with the mask must be the same as the mark
              value. The least significant bit in the mask is used as an
              increment. For example, if '0x200-0x400/0xff00' is specified,
              then the assigned mark values are 0x200, 0x300 and 0x400 in
              equal proportions. If no mask is specified, then ( 2 **
              MASK_BITS ) - 1 is assumed (MASK_BITS is set in <ulink
              url="shorewall.conf.html">shorewall.conf</ulink>(5)).</para>

              <para>May optionally be followed by <emphasis
              role="bold">:P</emphasis>, <emphasis
              role="bold">:F</emphasis>,<emphasis role="bold">:T</emphasis> or
              <emphasis role="bold">:I</emphasis> where<emphasis role="bold">
              :P</emphasis> indicates that marking should occur in the
              PREROUTING chain, <emphasis role="bold">:F</emphasis> indicates
              that marking should occur in the FORWARD chain, <emphasis
              role="bold">:I </emphasis>indicates that marking should occur in
              the INPUT chain (added in Shorewall 4.4.13), and <emphasis
              role="bold">:T</emphasis> indicates that marking should occur in
              the POSTROUTING chain. If neither <emphasis
              role="bold">:P</emphasis>, <emphasis role="bold">:F</emphasis>
              nor <emphasis role="bold">:T</emphasis> follow the mark value
              then the chain is determined as follows:</para>

              <para>- If the SOURCE is <emphasis
              role="bold">$FW</emphasis>[<emphasis
              role="bold">:</emphasis><emphasis>address-or-range</emphasis>[,<emphasis>address-or-range</emphasis>]...],
              then the rule is inserted into the OUTPUT chain. When
              HIGH_ROUTE_MARKS=Yes, only high mark values may be assigned
              there. Packet marking rules for traffic shaping of packets
              originating on the firewall must be coded in the POSTROUTING
              chain (see below).</para>

              <para>- Otherwise, the chain is determined by the setting of
              MARK_IN_FORWARD_CHAIN in <ulink
              url="shorewall.conf.html">shorewall.conf</ulink>(5).</para>

              <para>Please note that <emphasis role="bold">:I</emphasis> is
              included for completeness and affects neither traffic shaping
              nor policy routing.</para>

              <para>If your kernel and iptables include CONNMARK support then
              you can also mark the connection rather than the packet.</para>

              <para>The mark range and optional mask can then followed by one
              of:</para>

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

                  <listitem>
                    <para>Mark the connection in the chain determined by the
                    setting of MARK_IN_FORWARD_CHAIN</para>
                  </listitem>
                </varlistentry>

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

                  <listitem>
                    <para>Mark the connection in the FORWARD chain</para>
                  </listitem>
                </varlistentry>

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

                  <listitem>
                    <para>Mark the connection in the PREROUTING chain.</para>
                  </listitem>
                </varlistentry>

                <varlistentry>
                  <term>CT</term>

                  <listitem>
                    <para>Mark the connection in the POSTROUTING chain</para>
                  </listitem>
                </varlistentry>

                <varlistentry>
                  <term>CI</term>

                  <listitem>
                    <para>Mark the connection in the INPUT chain. This option
                    is included for completeness and has no applicability to
                    traffic shaping or policy routing.</para>
                  </listitem>
                </varlistentry>
              </variablelist>
            </listitem>

            <listitem>
              <para>A classification Id (classid) of the form
              <emphasis>major</emphasis>:<emphasis>minor</emphasis> where
              <emphasis>major</emphasis> and <emphasis>minor</emphasis> are
              integers. Corresponds to the 'class' specification in these
              traffic shaping modules:</para>

              <programlisting>       atm
       cbq
       dsmark
       pfifo_fast
       htb
       prio</programlisting>

              <para>Classification occurs in the POSTROUTING chain except when
              the <emphasis role="bold">SOURCE</emphasis> is <emphasis
              role="bold">$FW</emphasis>[:<emphasis>address</emphasis>] in
              which case classification occurs in the OUTPUT chain.</para>

              <para>When using Shorewall's built-in traffic shaping tool, the
              <emphasis>major</emphasis> class is the device number (the first
              device in <ulink
              url="shorewall-tcdevices.html">shorewall-tcdevices</ulink>(5) is
              major class 1, the second device is major class 2, and so on)
              and the <emphasis>minor</emphasis> class is the class's MARK
              value in <ulink
              url="shorewall-tcclasses.html">shorewall-tcclasses</ulink>(5)
              preceded by the number 1 (MARK 1 corresponds to minor class 11,
              MARK 5 corresponds to minor class 15, MARK 22 corresponds to
              minor class 122, etc.).</para>

              <para>Beginning with Shorewall 4.4.27, the classid may be
              optionally followed by ':' and a capital letter designating the
              chain where classification is to occur.</para>

              <variablelist>
                <varlistentry>
                  <term>F</term>

                  <listitem>
                    <para>FORWARD chain.</para>
                  </listitem>
                </varlistentry>

                <varlistentry>
                  <term>T</term>

                  <listitem>
                    <para>POSTROUTING chain (default).</para>
                  </listitem>
                </varlistentry>
              </variablelist>
            </listitem>

            <listitem>
              <para><emphasis role="bold">CHECKSUM</emphasis></para>

              <para>Added in Shorewall 4.5.9. Compute and fill in the checksum
              in a packet that lacks a checksum. This is particularly useful
              if you need to work around old applications, such as dhcp
              clients, that do not work well with checksum offloads, but you
              don't want to disable checksum offload in your device.</para>

              <para>Requires 'Checksum Target' support in your kernel and
              iptables.</para>
            </listitem>

            <listitem>
              <para><emphasis role="bold">[?]COMMENT</emphasis> -- the rest of
              the line will be attached as a comment to the Netfilter rule(s)
              generated by the following entries. The comment will appear
              delimited by "/* ... */" in the output of <command>shorewall
              show mangle</command></para>

              <para>To stop the comment from being attached to further rules,
              simply include COMMENT on a line by itself.</para>

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

            <listitem>
              <para><emphasis role="bold">CONTINUE</emphasis> Don't process
              any more marking rules ‒in the table.</para>

              <para>As in 1) above, may be followed by <emphasis
              role="bold">:P</emphasis> or <emphasis
              role="bold">:F</emphasis>. Currently, CONTINUE may not be used
              with <emphasis>exclusion</emphasis> (see the SOURCE and DEST
              columns below); that restriction will be removed when
              iptables/Netfilter provides the necessary support.</para>
            </listitem>

            <listitem>
              <para><emphasis role="bold">DIVERT</emphasis></para>

              <para>Added in Shorewall 4.5.4 and only available when FORMAT is
              2. Two DIVERT rule should precede the TPROXY rule and should
              select DEST PORT tcp 80 and SOURCE PORT tcp 80 respectively
              (assuming that tcp port 80 is being proxied). DIVERT avoids
              sending packets to the TPROXY target once a socket connection to
              Squid3 has been established by TPROXY. DIVERT marks the packet
              with a unique mark and exempts it from any rules that
              follow.</para>
            </listitem>

            <listitem>
              <para><emphasis role="bold">DROP</emphasis></para>

              <para>Added in Shorewall 4.5.21.4. Causes matching packets to be
              discarded.</para>
            </listitem>

            <listitem>
              <para><emphasis
              role="bold">DSCP</emphasis>(<replaceable>dscp</replaceable>)</para>

              <para>Added in Shorewall 4.5.1. Sets the
              <firstterm>Differentiated Services Code Point</firstterm> field
              in the IP header. The <replaceable>dscp</replaceable> value may
              be given as an even number (hex or decimal) or as the name of a
              DSCP class. Valid class names and their associated hex numeric
              values are:</para>

              <programlisting>    CS0  =&gt; 0x00
    CS1  =&gt; 0x08
    CS2  =&gt; 0x10
    CS3  =&gt; 0x18
    CS4  =&gt; 0x20
    CS5  =&gt; 0x28
    CS6  =&gt; 0x30
    CS7  =&gt; 0x38
    BE   =&gt; 0x00
    AF11 =&gt; 0x0a
    AF12 =&gt; 0x0c
    AF13 =&gt; 0x0e
    AF21 =&gt; 0x12
    AF22 =&gt; 0x14
    AF23 =&gt; 0x16
    AF31 =&gt; 0x1a
    AF32 =&gt; 0x1c
    AF33 =&gt; 0x1e
    AF41 =&gt; 0x22
    AF42 =&gt; 0x24
    AF43 =&gt; 0x26
    EF   =&gt; 0x2e</programlisting>

              <para>To indicate more than one class, add their hex values
              together and specify the result.</para>

              <para>May be optionally followed by ':' and a capital letter
              designating the chain where classification is to occur.</para>

              <variablelist>
                <varlistentry>
                  <term>F</term>

                  <listitem>
                    <para>FORWARD chain.</para>
                  </listitem>
                </varlistentry>

                <varlistentry>
                  <term>T</term>

                  <listitem>
                    <para>POSTROUTING chain (default).</para>
                  </listitem>
                </varlistentry>
              </variablelist>
            </listitem>

            <listitem>
              <para><emphasis
              role="bold">IMQ</emphasis>(<replaceable>number</replaceable>)</para>

              <para>Added in Shorewall 4.5.1. Specifies that the packet should
              be passed to the IMQ identified by
              <replaceable>number</replaceable>. Requires IMQ Target support
              in your kernel and iptables.</para>
            </listitem>

            <listitem>
              <para><emphasis role="bold">IPMARK</emphasis> ‒ Assigns a mark
              to each matching packet based on the either the source or
              destination IP address. By default, it assigns a mark value
              equal to the low-order 8 bits of the source address. Default
              values are:</para>

              <simplelist>
                <member>src</member>

                <member><emphasis>mask1</emphasis> = 0xFF</member>

                <member><emphasis>mask2</emphasis> = 0x00</member>

                <member><emphasis>shift</emphasis> = 0</member>
              </simplelist>

              <para>'src' and 'dst' specify whether the mark is to be based on
              the source or destination address respectively. The selected
              address is first shifted to the right by
              <emphasis>shift</emphasis> bits. The result is then LANDed with
              <emphasis>mask1</emphasis> then LORed with
              <emphasis>ma<emphasis>s</emphasis>k2</emphasis>.</para>

              <para>In a sense, the IPMARK target is more like an IPCLASSIFY
              target in that the mark value is later interpreted as a class
              ID. A packet mark is 32 bits wide; so is a class ID. The
              &lt;major&gt; class occupies the high-order 16 bits and the
              &lt;minor&gt; class occupies the low-order 16 bits. So the class
              ID 1:4ff (remember that class IDs are always in hex) is
              equivalent to a mark value of 0x104ff. Remember that Shorewall
              uses the interface number as the &lt;major&gt; number where the
              first interface in tcdevices has &lt;major&gt; number 1, the
              second has &lt;major&gt; number 2, and so on.</para>

              <para>The IPMARK target assigns a mark to each matching packet
              based on the either the source or destination IP address. By
              default, it assigns a mark value equal to the low-order 8 bits
              of the source address. The syntax is as follows:</para>

              <blockquote>
                <para><option>IPMARK</option>[([{<option>src</option>|<option>dst</option>}][,[<replaceable>mask1</replaceable>][,[<replaceable>mask2</replaceable>][,[<replaceable>shift</replaceable>]]]])]</para>
              </blockquote>

              <para>Default values are:</para>

              <simplelist>
                <member><option>src</option></member>

                <member><replaceable>mask1</replaceable> = 0xFF</member>

                <member><replaceable>mask2</replaceable> = 0x00</member>

                <member><replaceable>shift</replaceable> = 0</member>
              </simplelist>

              <para><option>src</option> and <option>dst</option> specify
              whether the mark is to be based on the source or destination
              address respectively. The selected address is first shifted
              right by <replaceable>shift</replaceable>, then LANDed with
              <replaceable>mask1</replaceable> and then LORed with
              <replaceable>mask2</replaceable>. The
              <replaceable>shift</replaceable> argument is intended to be used
              primarily with IPv6 addresses.</para>

              <para>Example:</para>

              <blockquote>
                <para>IPMARK(src,0xff,0x10100)</para>

                <simplelist>
                  <member>Suppose that the source IP address is 192.168.4.3 =
                  0xc0a80403; then</member>

                  <member>0xc0a80403 &gt;&gt; 0 = 0xc0a80403</member>

                  <member>0xc0a80403 LAND 0xFF = 0x03</member>

                  <member>0x03 LOR 0x0x10100 = 0x10103 or class ID
                  1:103</member>
                </simplelist>
              </blockquote>

              <para>It is important to realize that, while class IDs are
              composed of a <replaceable>major</replaceable> and a
              <replaceable>minor</replaceable> value, the set of values must
              be unique. That is, the same numeric value cannot be used as
              both a <replaceable>major</replaceable> and a
              <replaceable>minor</replaceable> number for the same interface
              unless class nesting occurs (which is not currently possible
              with Shorewall). You should keep this in mind when deciding how
              to map IP addresses to class IDs.</para>

              <para>For example, suppose that your internal network is
              192.168.1.0/29 (host IP addresses 192.168.1.1 - 192.168.1.6).
              Your first notion might be to use IPMARK(src,0xFF,0x10000) so as
              to produce class IDs 1:1 through 1:6. But 1:1 is an invalid
              class ID since the <replaceable>major</replaceable> and
              <replaceable>minor</replaceable> classes are equal. So you might
              choose instead to use IPMARK(src,0xFF,0x10100) as in the example
              above so that all of your <replaceable>minor</replaceable>
              classes will have a value &gt; 256.</para>
            </listitem>

            <listitem>
              <para><emphasis
              role="bold">RESTORE</emphasis>[/<emphasis>mask</emphasis>] --
              restore the packet's mark from the connection's mark using the
              supplied mask if any. Your kernel and iptables must include
              CONNMARK support.</para>

              <para>As in 1) above, may be followed by <emphasis
              role="bold">:P</emphasis> or <emphasis
              role="bold">:F</emphasis></para>
            </listitem>

            <listitem>
              <para><emphasis role="bold">SAME</emphasis> Some websites run
              applications that require multiple connections from a client
              browser. Where multiple 'balanced' providers are configured,
              this can lead to problems when some of the connections are
              routed through one provider and some through another. The SAME
              target allows you to work around that problem. SAME may be used
              in the PREROUTING and OUTPUT chains. When used in PREROUTING, it
              causes matching connections from an individual local system to
              all use the same provider. For example: <programlisting>#ACTION           SOURCE         DEST         PROTO      DEST
#                                                        PORT(S)
SAME:P            192.168.1.0/24 0.0.0.0/0    tcp        80,443</programlisting>
              If a host in 192.168.1.0/24 attempts a connection on TCP port 80
              or 443 and it has sent a packet on either of those ports in the
              last five minutes then the new connection will use the same
              provider as the connection over which that last packet was
              sent.</para>

              <para>When used in the OUTPUT chain, it causes all matching
              connections to an individual remote system to all use the same
              provider. For example:<programlisting>#ACTION           SOURCE         DEST         PROTO      DEST
#                                                        PORT(S)
SAME              $FW            0.0.0.0/0    tcp        80,443</programlisting>
              If the firewall attempts a connection on TCP port 80 or 443 and
              it has sent a packet on either of those ports in the last five
              minutes to the same remote system then the new connection will
              use the same provider as the connection over which that last
              packet was sent.</para>
            </listitem>

            <listitem>
              <para><emphasis
              role="bold">SAVE</emphasis>[/<emphasis>mask</emphasis>] -- save
              the packet's mark to the connection's mark using the supplied
              mask if any. Your kernel and iptables must include CONNMARK
              support.</para>

              <para>As in 1) above, may be followed by <emphasis
              role="bold">:P</emphasis> or <emphasis
              role="bold">:F</emphasis></para>
            </listitem>

            <listitem>
              <para><emphasis role="bold">STATE</emphasis> {<emphasis
              role="bold">NEW</emphasis>|<emphasis
              role="bold">RELATED</emphasis>|<emphasis
              role="bold">ESTABLISHED</emphasis>|<emphasis
              role="bold">INVALID</emphasis>} [,...]</para>

              <para>Added in Shorewall 4.5.9. The rule will only match if the
              packet's connection is in one of the listed states.</para>
            </listitem>

            <listitem>
              <para><emphasis
              role="bold">TOS</emphasis>(<replaceable>tos</replaceable>[/<replaceable>mask</replaceable>])</para>

              <para>Added in Shorewall 4.5.1. Sets the <firstterm>Type of
              Service</firstterm> field in the IP header. The
              <replaceable>tos</replaceable> value may be given as an number
              (hex or decimal) or as the name of a TOS type. Valid type names
              and their associated hex numeric values are:</para>

              <programlisting>Minimize-Delay       =&gt; 0x10,
Maximize-Throughput  =&gt; 0x08,
Maximize-Reliability =&gt; 0x04,
Minimize-Cost        =&gt; 0x02,
Normal-Service       =&gt; 0x00</programlisting>

              <para>To indicate more than one class, add their hex values
              together and specify the result.</para>

              <para>When <replaceable>tos</replaceable> is given as a number,
              it may be optionally followed by '/' and a
              <replaceable>mask</replaceable>. When no
              <replaceable>mask</replaceable> is given, the value 0xff is
              assumed. When <replaceable>tos</replaceable> is given as a type
              name, the <replaceable>mask</replaceable> 0x3f is
              assumed.</para>

              <para>The action performed is to zero out the bits specified by
              the <replaceable>mask</replaceable>, then set the bits specified
              by <replaceable>tos</replaceable>.</para>

              <para>May be optionally followed by ':' and a capital letter
              designating the chain where classification is to occur.</para>

              <variablelist>
                <varlistentry>
                  <term>F</term>

                  <listitem>
                    <para>FORWARD chain.</para>
                  </listitem>
                </varlistentry>

                <varlistentry>
                  <term>T</term>

                  <listitem>
                    <para>POSTROUTING chain.</para>
                  </listitem>
                </varlistentry>
              </variablelist>
            </listitem>

            <listitem>
              <para><emphasis
              role="bold">TPROXY</emphasis>(<replaceable>mark</replaceable>[,[<replaceable>port</replaceable>][,[<replaceable>address</replaceable>]]])
              -- FORMAT 1</para>

              <para>Transparently redirects a packet without altering the IP
              header. Requires a local provider to be defined in <ulink
              url="shorewall-providers.html">shorewall-providers</ulink>(5).</para>

              <para>There are three parameters to TPROXY - only the first
              (mark) is required:</para>

              <itemizedlist>
                <listitem>
                  <para><replaceable>mark</replaceable> - the MARK value
                  corresponding to the local provider in <ulink
                  url="shorewall-providers.html">shorewall-providers</ulink>(5).</para>
                </listitem>

                <listitem>
                  <para><replaceable>port</replaceable> - the port on which
                  the proxy server is listening. If omitted, the original
                  destination port.</para>
                </listitem>

                <listitem>
                  <para><replaceable>address</replaceable> - a local (to the
                  firewall) IP address on which the proxy server is listening.
                  If omitted, the IP address of the interface on which the
                  request arrives.</para>
                </listitem>
              </itemizedlist>
            </listitem>

            <listitem>
              <para><emphasis
              role="bold">TPROXY</emphasis>([<replaceable>port</replaceable>][,<replaceable>address</replaceable>])
              -- FORMAT 2</para>

              <para>Transparently redirects a packet without altering the IP
              header. Requires a tproxy provider to be defined in <ulink
              url="shorewall-providers.html">shorewall-providers</ulink>(5).</para>

              <para>There are three parameters to TPROXY - neither is
              required:</para>

              <itemizedlist>
                <listitem>
                  <para><replaceable>port</replaceable> - the port on which
                  the proxy server is listening. If omitted, the original
                  destination port.</para>
                </listitem>

                <listitem>
                  <para><replaceable>address</replaceable> - a local (to the
                  firewall) IP address on which the proxy server is listening.
                  If omitted, the IP address of the interface on which the
                  request arrives.</para>
                </listitem>
              </itemizedlist>
            </listitem>

            <listitem>
              <para><emphasis role="bold">TTL</emphasis>([<emphasis
              role="bold">-</emphasis>|<emphasis
              role="bold">+</emphasis>]<replaceable>number</replaceable>)</para>

              <para>Added in Shorewall 4.4.24.</para>

              <para>Prior to Shorewall 4.5.7.2, may be optionally followed by
              <emphasis role="bold">:F</emphasis> but the resulting rule is
              always added to the FORWARD chain. Beginning with Shorewall
              4.5.7.s, it may be optionally followed by <emphasis
              role="bold">:P</emphasis>, in which case the rule is added to
              the PREROUTING chain.</para>

              <para>If <emphasis role="bold">+</emphasis> is included, packets
              matching the rule will have their TTL incremented by
              <replaceable>number</replaceable>. Similarly, if <emphasis
              role="bold">-</emphasis> is included, matching packets have
              their TTL decremented by <replaceable>number</replaceable>. If
              neither <emphasis role="bold">+</emphasis> nor <emphasis
              role="bold">-</emphasis> is given, the TTL of matching packets
              is set to <replaceable>number</replaceable>. The valid range of
              values for <replaceable>number</replaceable> is 1-255.</para>
            </listitem>
          </orderedlist>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">SOURCE</emphasis> - {<emphasis
        role="bold">-</emphasis>|{<emphasis>interface</emphasis>|<emphasis
        role="bold">$FW</emphasis>}|[{<emphasis>interface</emphasis>|<emphasis
        role="bold">$FW</emphasis>}:]<emphasis>address-or-range</emphasis>[<emphasis
        role="bold">,</emphasis><emphasis>address-or-range</emphasis>]...}[<emphasis>exclusion</emphasis>]</term>

        <listitem>
          <para>May be:</para>

          <orderedlist>
            <listitem>
              <para>An interface name - matches traffic entering the firewall
              on the specified interface. May not be used in classify rules or
              in rules using the :T chain qualifier.</para>
            </listitem>

            <listitem>
              <para>A comma-separated list of host or network IP addresses or
              MAC addresses. <emphasis role="bold">This form will not match
              traffic that originates on the firewall itself unless either
              &lt;major&gt;&lt;minor&gt; or the :T chain qualifier is used in
              the ACTION column.</emphasis></para>

              <para>Examples:<simplelist>
                  <member>0.0.0.0/0</member>
                </simplelist></para>

              <para><simplelist>
                  <member>192.168.1.0/24, 172.20.4.0/24</member>
                </simplelist></para>
            </listitem>

            <listitem>
              <para>An interface name followed by a colon (":") followed by a
              comma-separated list of host or network IP addresses or MAC
              addresses. May not be used in classify rules or in rules using
              the :T chain qualifier.</para>
            </listitem>

            <listitem>
              <para>$FW optionally followed by a colon (":") and a
              comma-separated list of host or network IP addresses. Matches
              packets originating on the firewall. May not be used with a
              chain qualifier (:P, :F, etc.) in the ACTION column.</para>
            </listitem>
          </orderedlist>

          <para>MAC addresses must be prefixed with "~" and use "-" as a
          separator.</para>

          <para>Example: ~00-A0-C9-15-39-78</para>

          <para>You may exclude certain hosts from the set already defined
          through use of an <emphasis>exclusion</emphasis> (see <ulink
          url="shorewall-exclusion.html">shorewall-exclusion</ulink>(5)).</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">DEST</emphasis> - {<emphasis
        role="bold">-</emphasis>|{<emphasis>interface</emphasis>|$FW}|[<emphasis>{interface</emphasis>|$FW}:]<emphasis>address-or-range</emphasis>[<emphasis
        role="bold">,</emphasis><emphasis>address-or-range</emphasis>]...}[<emphasis>exclusion</emphasis>]</term>

        <listitem>
          <para>May be:</para>

          <orderedlist>
            <listitem>
              <para>An interface name. May not be used in the PREROUTING chain
              (:P in the mark column or no chain qualifier and
              MARK_IN_FORWARD_CHAIN=No in <ulink
              url="manpages/shorewall.conf">shorewall.conf</ulink> (5)). The
              interface name may be optionally followed by a colon (":") and
              an IP address list.</para>
            </listitem>

            <listitem>
              <para>A comma-separated list of host or network IP addresses.
              The list may include ip address ranges if your kernel and
              iptables include iprange support.</para>
            </listitem>

            <listitem>
              <para>Beginning with Shorewall 4.4.13, $FW may be specified by
              itself or qualified by an address list. This causes marking to
              occur in the INPUT chain.</para>
            </listitem>
          </orderedlist>

          <para>You may exclude certain hosts from the set already defined
          through use of an <emphasis>exclusion</emphasis> (see <ulink
          url="shorewall-exclusion.html">shorewall-exclusion</ulink>(5)).</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">PROTO</emphasis> - {<emphasis
        role="bold">-</emphasis>|<emphasis
        role="bold">{tcp:syn</emphasis>|<emphasis
        role="bold">ipp2p</emphasis>|<emphasis
        role="bold">ipp2p:udp</emphasis>|<emphasis
        role="bold">ipp2p:all</emphasis>|<emphasis>protocol-number</emphasis>|<emphasis>protocol-name</emphasis>|<emphasis
        role="bold">all}[,...]}</emphasis></term>

        <listitem>
          <para>Protocol - <emphasis role="bold">ipp2p</emphasis> requires
          ipp2p match support in your kernel and iptables.</para>

          <para>Beginning with Shorewall 4.5.12, this column can accept a
          comma-separated list of protocols.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">PORT(S)</emphasis> (dport) - [<emphasis
        role="bold">-</emphasis>|<emphasis>port-name-number-or-range</emphasis>[<emphasis
        role="bold">,</emphasis><emphasis>port-name-number-or-range</emphasis>]...]</term>

        <listitem>
          <para>Optional destination Ports. A comma-separated list of Port
          names (from services(5)), <emphasis>port number</emphasis>s or
          <emphasis>port range</emphasis>s; if the protocol is <emphasis
          role="bold">icmp</emphasis>, this column is interpreted as the
          destination icmp-type(s). ICMP types may be specified as a numeric
          type, a numeric type and code separated by a slash (e.g., 3/4), or a
          typename. See <ulink
          url="http://www.shorewall.net/configuration_file_basics.htm#ICMP">http://www.shorewall.net/configuration_file_basics.htm#ICMP</ulink>.</para>

          <para>If the protocol is <emphasis role="bold">ipp2p</emphasis>,
          this column is interpreted as an ipp2p option without the leading
          "--" (example <emphasis role="bold">bit</emphasis> for bit-torrent).
          If no PORT is given, <emphasis role="bold">ipp2p</emphasis> is
          assumed.</para>

          <para>An entry in this field requires that the PROTO column specify
          icmp (1), tcp (6), udp (17), sctp (132) or udplite (136). Use '-' if
          any of the following field is supplied.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">SOURCE PORT(S)</emphasis> (sport) -
        [<emphasis
        role="bold">-</emphasis>|<emphasis>port-name-number-or-range</emphasis>[<emphasis
        role="bold">,</emphasis><emphasis>port-name-number-or-range</emphasis>]...]</term>

        <listitem>
          <para>Optional source port(s). If omitted, any source port is
          acceptable. Specified as a comma-separated list of port names, port
          numbers or port ranges.</para>

          <para>An entry in this field requires that the PROTO column specify
          tcp (6), udp (17), sctp (132) or udplite (136). Use '-' if any of
          the following fields is supplied.</para>

          <para>Beginning with Shorewall 4.5.15, you may place '=' in this
          column, provided that the DEST PORT(S) 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
          DEST PORTS(S). Use of '=' requires multi-port match in your iptables
          and kernel.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">USER</emphasis> - [<emphasis
        role="bold">!</emphasis>][<emphasis>user-name-or-number</emphasis>][<emphasis
        role="bold">:</emphasis><emphasis>group-name-or-number</emphasis>][<emphasis
        role="bold">+</emphasis><emphasis>program-name</emphasis>]</term>

        <listitem>
          <para>This optional column may only be non-empty if the SOURCE is
          the firewall itself.</para>

          <para>When this column is non-empty, the rule applies only if the
          program generating the output is running under the effective
          <emphasis>user</emphasis> and/or <emphasis>group</emphasis>
          specified (or is NOT running under that id if "!" is given).</para>

          <para>Examples:</para>

          <variablelist>
            <varlistentry>
              <term>joe</term>

              <listitem>
                <para>program must be run by joe</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term>:kids</term>

              <listitem>
                <para>program must be run by a member of the 'kids'
                group</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term>!:kids</term>

              <listitem>
                <para>program must not be run by a member of the 'kids'
                group</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term>+upnpd</term>

              <listitem>
                <para>#program named upnpd</para>

                <important>
                  <para>The ability to specify a program name was removed from
                  Netfilter in kernel version 2.6.14.</para>
                </important>
              </listitem>
            </varlistentry>
          </variablelist>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">TEST</emphasis> - [<emphasis
        role="bold">!</emphasis>]<emphasis>value</emphasis>[/<emphasis>mask</emphasis>][<emphasis
        role="bold">:C</emphasis>]</term>

        <listitem>
          <para>Optional - Defines a test on the existing packet or connection
          mark. The rule will match only if the test returns true.</para>

          <para>If you don't want to define a test but need to specify
          anything in the following columns, place a "-" in this field.</para>

          <variablelist>
            <varlistentry>
              <term>!</term>

              <listitem>
                <para>Inverts the test (not equal)</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis>value</emphasis></term>

              <listitem>
                <para>Value of the packet or connection mark.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis>mask</emphasis></term>

              <listitem>
                <para>A mask to be applied to the mark before testing.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis role="bold">:C</emphasis></term>

              <listitem>
                <para>Designates a connection mark. If omitted, the packet
                mark's value is tested.</para>
              </listitem>
            </varlistentry>
          </variablelist>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">LENGTH</emphasis> -
        [<emphasis>length</emphasis>|[<emphasis>min</emphasis>]<emphasis
        role="bold">:</emphasis>[<emphasis>max</emphasis>]]</term>

        <listitem>
          <para>Optional - packet payload length. This field, if present allow
          you to match the length of a packet payload (Layer 4 data ) against
          a specific value or range of values. You must have iptables length
          support for this to work. A range is specified in the form
          <emphasis>min</emphasis>:<emphasis>max</emphasis> where either
          <emphasis>min</emphasis> or <emphasis>max</emphasis> (but not both)
          may be omitted. If <emphasis>min</emphasis> is omitted, then 0 is
          assumed; if <emphasis>max</emphasis> is omitted, than any packet
          that is <emphasis>min</emphasis> or longer will match.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">TOS</emphasis> -
        <emphasis>tos</emphasis></term>

        <listitem>
          <para>Type of service. Either a standard name, or a numeric value to
          match.</para>

          <programlisting>         <emphasis role="bold">Minimize-Delay</emphasis> (16)
         <emphasis role="bold">Maximize-Throughput</emphasis> (8)
         <emphasis role="bold">Maximize-Reliability</emphasis> (4)
         <emphasis role="bold">Minimize-Cost</emphasis> (2)
         <emphasis role="bold">Normal-Service</emphasis> (0)</programlisting>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">CONNBYTES</emphasis> -
        [!]<emphasis>min</emphasis>:[<emphasis>max</emphasis>[:{<emphasis
        role="bold">O</emphasis>|<emphasis role="bold">R</emphasis>|<emphasis
        role="bold">B</emphasis>}[:{<emphasis
        role="bold">B</emphasis>|<emphasis role="bold">P</emphasis>|<emphasis
        role="bold">A</emphasis>}]]]</term>

        <listitem>
          <para>Optional connection Bytes; defines a byte or packet range that
          the connection must fall within in order for the rule to
          match.</para>

          <para>A packet matches if the the packet/byte count is within the
          range defined by <emphasis>min</emphasis> and
          <emphasis>max</emphasis> (unless ! is given in which case, a packet
          matches if the packet/byte count is not within the range).
          <emphasis>min</emphasis> is an integer which defines the beginning
          of the byte/packet range. <emphasis>max</emphasis> is an integer
          which defines the end of the byte/packet range; if omitted, only the
          beginning of the range is checked. The first letter gives the
          direction which the range refers to:<blockquote>
              <para><emphasis role="bold">O</emphasis> - The original
              direction of the connection.</para>

              <para>- The opposite direction from the original
              connection.</para>

              <para><emphasis role="bold">B</emphasis> - The total of both
              directions.</para>
            </blockquote></para>

          <para>If omitted, <emphasis role="bold">B</emphasis> is
          assumed.</para>

          <para>The second letter determines what the range refers
          to.<blockquote>
              <para><emphasis role="bold">B</emphasis> - Bytes</para>

              <para><emphasis role="bold">P</emphasis> - Packets</para>

              <para><emphasis role="bold">A</emphasis> - Average packet
              size.</para>
            </blockquote>If omitted, <emphasis role="bold">B</emphasis> is
          assumed.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">HELPER -
        </emphasis><emphasis>helper</emphasis></term>

        <listitem>
          <para>Names a Netfilter protocol <firstterm>helper</firstterm>
          module such as <option>ftp</option>, <option>sip</option>,
          <option>amanda</option>, etc. A packet will match if it was accepted
          by the named helper module.</para>

          <para>Example: Mark all FTP data connections with mark
          4:<programlisting>#ACTION   SOURCE    DEST      PROTO   PORT(S)    SOURCE  USER TEST LENGTH TOS CONNBYTES HELPER
#                                                PORT(S)
4:T       0.0.0.0/0 0.0.0.0/0 TCP     -          -       -    -    -      -   -         ftp</programlisting></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">PROBABILITY</emphasis> -
        [<replaceable>probability</replaceable>]</term>

        <listitem>
          <para>Added in Shorewall 4.5.0. When non-empty, requires the
          <firstterm>Statistics Match</firstterm> capability in your kernel
          and ip6tables and causes the rule to match randomly but with the
          given <replaceable>probability</replaceable>. The
          <replaceable>probability</replaceable> is a number 0 &lt;
          <replaceable>probability</replaceable> &lt;= 1 and may be expressed
          at up to 8 decimal points of precision.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">DSCP -</emphasis>
        [[!]<replaceable>dscp</replaceable>]</term>

        <listitem>
          <para>Added in Shorewall 4.5.1. When non-empty, match packets whose
          <firstterm>Differentiated Service Code Point</firstterm> field
          matches the supplied value (when '!' is given, the rule matches
          packets whose DSCP field does not match the supplied value). The
          <replaceable>dscp</replaceable> value may be given as an even number
          (hex or decimal) or as the name of a DSCP class. Valid class names
          and their associated hex numeric values are:</para>

          <programlisting>    CS0  =&gt; 0x00
    CS1  =&gt; 0x08
    CS2  =&gt; 0x10
    CS3  =&gt; 0x18
    CS4  =&gt; 0x20
    CS5  =&gt; 0x28
    CS6  =&gt; 0x30
    CS7  =&gt; 0x38
    BE   =&gt; 0x00
    AF11 =&gt; 0x0a
    AF12 =&gt; 0x0c
    AF13 =&gt; 0x0e
    AF21 =&gt; 0x12
    AF22 =&gt; 0x14
    AF23 =&gt; 0x16
    AF31 =&gt; 0x1a
    AF32 =&gt; 0x1c
    AF33 =&gt; 0x1e
    AF41 =&gt; 0x22
    AF42 =&gt; 0x24
    AF43 =&gt; 0x26
    EF   =&gt; 0x2e</programlisting>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Example</title>

    <variablelist>
      <varlistentry>
        <term>Example 1:</term>

        <listitem>
          <para>Mark all ICMP echo traffic with packet mark 1. Mark all peer
          to peer traffic with packet mark 4.</para>

          <para>This is a little more complex than otherwise expected. Since
          the ipp2p module is unable to determine all packets in a connection
          are P2P packets, we mark the entire connection as P2P if any of the
          packets are determined to match.</para>

          <para>We assume packet/connection mark 0 means unclassified.</para>

          <programlisting>       #ACTION    SOURCE    DEST         PROTO   PORT(S)       SOURCE  USER    TEST
       #                                                       PORT(S)
       1:T        0.0.0.0/0 0.0.0.0/0    icmp    echo-request
       1:T        0.0.0.0/0 0.0.0.0/0    icmp    echo-reply
       RESTORE:T  0.0.0.0/0 0.0.0.0/0    all     -             -       -       0
       CONTINUE:T 0.0.0.0/0 0.0.0.0/0    all     -             -       -       !0
       4:T         0.0.0.0/0 0.0.0.0/0   ipp2p:all
       SAVE:T      0.0.0.0/0 0.0.0.0/0   all     -             -       -       !0</programlisting>

          <para>If a packet hasn't been classified (packet mark is 0), copy
          the connection mark to the packet mark. If the packet mark is set,
          we're done. If the packet is P2P, set the packet mark to 4. If the
          packet mark has been set, save it to the connection mark.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>Example 2:</term>

        <listitem>
          <para>SNAT outgoing connections on eth0 from 192.168.1.0/24 in
          round-robin fashion between addresses 1.1.1.1, 1.1.1.3, and 1.1.1.9
          (Shorewall 4.5.9 and later).</para>

          <programlisting>/etc/shorewall/tcrules:

       #ACTION   SOURCE         DEST         PROTO   PORT(S)       SOURCE  USER    TEST
       #                                                           PORT(S)
       1-3:CF    192.168.1.0/24 eth0 ; state=NEW

/etc/shorewall/masq:

       #INTERFACE SOURCE         ADDRESS     ...
       eth0       192.168.1.0/24 1.1.1.1 ; mark=1:C
       eth0       192.168.1.0/24 1.1.1.3 ; mark=2:C
       eth0       192.168.1.0/24 1.1.1.4 ; mark=3:C</programlisting>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>FILES</title>

    <para>/etc/shorewall/tcrules</para>
  </refsect1>

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

    <para><ulink
    url="http://shorewall.net/traffic_shaping.htm">http://shorewall.net/traffic_shaping.htm</ulink></para>

    <para><ulink
    url="http://shorewall.net/MultiISP.html">http://shorewall.net/MultiISP.html</ulink></para>

    <para><ulink
    url="http://shorewall.net/PacketMarking.html">http://shorewall.net/PacketMarking.html</ulink></para>

    <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-ecn(5), shorewall-exclusion(5),
    shorewall-hosts(5), shorewall_interfaces(5), shorewall-ipsets(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-rtrules(5),
    shorewall-routestopped(5), shorewall-rules(5), shorewall.conf(5),
    shorewall-secmarks(5), shorewall-tcclasses(5), shorewall-tcdevices(5),
    shorewall-tos(5), shorewall-tunnels(5), shorewall-zones(5)</para>
  </refsect1>
</refentry>