forked from extern/shorewall_code
695 lines
28 KiB
XML
695 lines
28 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
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"http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd">
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<article>
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<!--$Id$-->
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<articleinfo>
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<title>Packet Marking using /etc/shorewall/tcrules</title>
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<authorgroup>
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<author>
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<firstname>Tom</firstname>
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<surname>Eastep</surname>
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</author>
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</authorgroup>
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<pubdate><?dbtimestamp format="Y/m/d"?></pubdate>
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<copyright>
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<year>2006</year>
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<year>2013</year>
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<holder>Thomas M. Eastep</holder>
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</copyright>
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<legalnotice>
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<para>Permission is granted to copy, distribute and/or modify this
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document under the terms of the GNU Free Documentation License, Version
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1.2 or any later version published by the Free Software Foundation; with
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no Invariant Sections, with no Front-Cover, and with no Back-Cover
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Texts. A copy of the license is included in the section entitled
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<quote><ulink url="GnuCopyright.htm">GNU Free Documentation
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License</ulink></quote>.</para>
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</legalnotice>
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</articleinfo>
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<caution>
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<para>This article includes information that applies to Shorewall version
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3.2.5 and later. Not all features described here will be available in
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earlier releases.</para>
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</caution>
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<section id="Marks">
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<title>Packet and Connection Marks</title>
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<para>Perhaps no aspect of Shorewall causes more confusion than packet
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marking. This article will attempt to clear up some of that
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confusion.</para>
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<para>Each packet has a mark whose value is initially 0. Mark values are
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stored in the <emphasis>skb</emphasis> (socket buffer) structure used by
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the Linux kernel to track packets; the mark value is not part of the
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packet itself and cannot be seen with <command>tcpdump</command>,
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<command>ethereal</command> or any other packet sniffing program. They can
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be seen in an iptables/ip6tables trace -- see the
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<command>iptrace</command> command in <ulink
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url="manpages/shorewall.html">shorewall</ulink>(8) and <ulink
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url="manpages6/shorewall6.html">shorewall6</ulink>(8).</para>
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<para>Example (output has been folded for display ):</para>
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<programlisting>[11692.096077] TRACE: mangle:tcout:return:3 IN= OUT=eth0 SRC=172.20.1.130
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DST=206.124.146.254 LEN=84 TOS=0x00 PREC=0x00 TTL=64
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ID=0 DF PROTO=ICMP TYPE=8 CODE=0 ID=7212 SEQ=3 UID=0
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GID=1000 <emphasis role="bold">MARK=0x10082</emphasis></programlisting>
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<para>Each active connection (even those that are not yet in ESTABLISHED
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state) has a mark value that is distinct from the packet marks. Connection
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mark values can be seen using the <command>shorewall show
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connections</command> command. The default connection mark value is
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0.</para>
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<para>Example (output has been folded for display ):</para>
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<programlisting><command>shorewall show connections</command>
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Shorewall 3.3.2 Connections at gateway - Mon Oct 2 09:08:18 PDT 2006
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tcp 6 19 TIME_WAIT src=206.124.146.176 dst=192.136.34.98 sport=58597 dport=80
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packets=23 bytes=4623 src=192.136.34.98 dst=206.124.146.176 sport=80 dport=58597
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packets=23 bytes=22532 [ASSURED] <emphasis role="bold">mark=256</emphasis> use=1
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…</programlisting>
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<para>Packet marks are valid only while the packet is being processed by
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the firewall. Once the packet has been given to a local process or sent on
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to another system, the packet's mark value is no longer available.
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Connection mark values, on the other hand, persist for the life of the
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connection.</para>
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<important>
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<para>Other parts of the system such as <ulink
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url="traffic_shaping.htm">Traffic Shaping</ulink> and <ulink
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url="MultiISP.html">Policy Routing</ulink> cannot use connection marks —
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they can only use packet marks.</para>
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</important>
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</section>
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<section id="Programs">
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<title>Packet Marking "Programs"</title>
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<para>Packet marking occurs in Netfilter's <emphasis>mangle</emphasis>
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table. See the <ulink url="NetfilterOverview.html">Netfilter
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Overview</ulink> article.</para>
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<para>You can think of entries in the tcrules file like instructions in a
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program coded in a crude assembly language. The program gets executed for
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each packet.</para>
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<para>That is another way of saying that <emphasis role="bold">if you
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don't program, you may have difficulty making full use of
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Netfilter/Shorewall's Packet Marking</emphasis>.</para>
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<para>Actually, the tcrules define several programs. Each program
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corresponds to one of the built-in chains in the mangle table.</para>
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<itemizedlist>
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<listitem>
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<para>PREROUTING program — If MARK_IN_FORWARD_CHAIN=No in
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<filename>shorewall.conf</filename>, then by default entries in
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<filename>/etc/shorewall/tcrules</filename> are part of the PREROUTING
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program. Entries specifying the ":P" suffix in the ACTION column are
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also part of the PREROUTING program. The PREROUTING program gets
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executed for each packet entering the firewall.</para>
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</listitem>
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<listitem>
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<para>FORWARD program — If MARK_IN_FORWARD_CHAIN=Yes in
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<filename>shorewall.conf</filename>, then by default entries in
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<filename>/etc/shorewall/tcrules</filename> are part of the FORWARD
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program. Entries specifying the ":F" suffix in the ACTION column are
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also part of the FORWARD program. The FORWARD program gets executed
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for each packet forwarded by the firewall.</para>
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</listitem>
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<listitem>
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<para>OUTPUT program — Entries with $FW in the SOURCE column are part
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of the OUTPUT program. The OUTPUT program is executed for each packet
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originating on the firewall itself.</para>
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</listitem>
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<listitem>
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<para>POSTROUTING program — Entries with a class-id in the ACTION
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column (and that don't specify $FW in the SOURCE column) are part of
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the POSTROUTING program. These rules are executed for each packet
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leaving the firewall. Entries specifying the ":T" suffix in the ACTION
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column are also part of the POSTROUTING program (Shorewall version
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3.4.0 and later).</para>
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</listitem>
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<listitem>
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<para>INPUT program — No entries in tcrules will add entries to this
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program. It is executed for each packet that is targeted to the
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firewall itself.</para>
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</listitem>
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</itemizedlist>
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<para>Note that a packet being forwarded by your firewall actually gets
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processed by three different programs: PREROUTING, FORWARD and
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POSTROUTING. Similarly, packets addressed to the firewall itself are
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processed by two programs (PREROUTING and INPUT) while packets originating
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on the firewall are likewise processed by two programs (OUTPUT and
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POSTROUTING).</para>
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<para>Rules in each program are <emphasis>executed</emphasis> as
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follows:</para>
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<itemizedlist>
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<listitem>
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<para>Rules are conditionally executed based on whether the current
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packet matches the contents of the SOURCE, DEST, PROTO, PORT(S),
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CLIENT PORT(S_, USER, TEST, LENGTH and TOS columns.</para>
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</listitem>
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<listitem>
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<para>When a rule is executed, either:</para>
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<orderedlist>
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<listitem>
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<para>the current packet receives a new mark value; or</para>
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</listitem>
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<listitem>
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<para>the connection to which the current packet belongs receives
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a new mark value (":C", ":CF" or ":CP" suffix in the ACTION
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column); or</para>
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</listitem>
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<listitem>
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<para>the packet is classified for traffic shaping (class-id in
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the ACTION column); or</para>
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</listitem>
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<listitem>
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<para>the packet mark in the current packet is moved to the
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connection mark for the connection that the current packet is part
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of ("SAVE" in the ACTION column); or</para>
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</listitem>
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<listitem>
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<para>the connection mark value for the connection that the
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current packet is part of is moved to the current packet's mark
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("RESTORE" in the ACTION column); or</para>
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</listitem>
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<listitem>
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<para>jump to a subroutine (another chain in the mangle table).
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These jumps are generated by Shorewall; or</para>
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</listitem>
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<listitem>
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<para>exit the current subroutine ("CONTINUE" in the ACTION
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column).</para>
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</listitem>
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</orderedlist>
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</listitem>
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<listitem>
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<para>Unless the subroutine is exited using CONTINUE, <emphasis
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role="bold">the current packet is always passed to the next tcrule in
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the subroutine</emphasis>.</para>
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</listitem>
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</itemizedlist>
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</section>
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<section id="Values">
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<title>Mark and Mask Values</title>
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<para>The mark value is held in a 32-bit field. Because packet marking is
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the Netfilter <emphasis>kludge of last resort</emphasis> for solving many
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hard technical problems, Shorewall originally reserved half of this field
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(16 bits) for future use. The remainder was split into two 8-bit
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values:</para>
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<itemizedlist>
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<listitem>
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<para>The low-order eight bits are used for traffic shaping marks.
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These eight bits were also used for selecting among multiple providers
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when HIGH_ROUTE_MARKS=No in <filename>shorewall.conf</filename>. Some
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rules that deal with only these bits used a mask value of 0xff.</para>
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</listitem>
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<listitem>
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<para>The next 8 bits were used for selecting among multiple providers
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when HIGH_ROUTE_MARKS=Yes in <filename>shorewall.conf</filename>.
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These bits are manipulated using a mask value of 0xff00.</para>
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</listitem>
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</itemizedlist>
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<para>As hinted above, marking rules can specify both a mark value and a
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mask. The mask determines the subset of the 32 bits in the mark to be used
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in the operation — only those bits that are on in the mask are manipulated
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when the rule is executed. For entries in tcrules, Shorewall-generated
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rules use a mask value that depends on which program the rule is part of,
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what the rule does, and the setting of HIGH_ROUTE_MARKS.</para>
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<para>For entries in tcrules, the default mask value is 0xffff except in
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these cases:</para>
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<itemizedlist>
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<listitem>
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<para>RESTORE rules use a default mask value of 0xff.</para>
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</listitem>
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<listitem>
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<para>SAVE rules use a default mask value of 0xff.</para>
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</listitem>
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<listitem>
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<para>Connection marking rules use a mask value of 0xff.</para>
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</listitem>
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</itemizedlist>
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<para>When WIDE_TC_MARKS was added, the number of bits reserved for TC
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marks was increased to 14 when WIDE_TC_MARKS=Yes and the provider mark
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field (when HIGH_ROUTE_MARKS=Yes) was offset 16 bits. Also, when
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HIGH_ROUTE_MARKS=Yes, the mask used for setting/testing TC marks was
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0xffff (16 bits).</para>
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<para>Shorewall actually allows you to have complete control over the
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layout of the 32-bit mark using the following options in <ulink
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url="manpages/shorewall.conf.html">shorewall.conf</ulink> (5) (these
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options were documented in the <ulink
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url="manpages/shorewall.conf.html">shorewall.conf</ulink>(5) manpage in
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Shorewall 4.4.26):</para>
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<variablelist>
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<varlistentry>
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<term>TC_BITS</term>
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<listitem>
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<para>The number of bits at the low end of the mark to be used for
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traffic shaping marking. May be zero.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>PROVIDER_BITS</term>
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<listitem>
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<para>The number of bits in the mark to be used for provider
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numbers. May be zero.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>PROVIDER_OFFSET</term>
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<listitem>
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<para>The offset from the right (low-order end) of the provider
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number field. If non-zero, must be >= TC_BITS (Shorewall
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automatically adjusts PROVIDER_OFFSET's value). PROVIDER_OFFSET +
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PROVIDER_BITS must be <= 32.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>MASK_BITS</term>
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<listitem>
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<para>Number of bits on the right of the mark to be masked when
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clearing the traffic shaping mark. Must be >= TC_BITS and <=
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PROVIDER_OFFSET (if PROVIDER_OFFSET > 0)</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>In Shorewall 4.4.26, a new option was added:</para>
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<variablelist>
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<varlistentry>
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<term>ZONE_BITS</term>
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<listitem>
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<para>Number of bits in the mark to use for automatic zone marking
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(see the <ulink url="bridge-Shorewall-perl.html">Shorewall
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Bridge/Firewall HOWTO</ulink>).</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>The relationship between these options is shown in this
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diagram.</para>
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<graphic align="left" fileref="images/MarkGeometry.png" valign="top" />
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<para>The default values of these options are determined by the settings
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of other options as follows:</para>
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<table>
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<title>Default Values</title>
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<tgroup cols="2">
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<tbody>
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<row>
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<entry>WIDE_TC_MARKS=No, HIGH_ROUTE_MARKS=No</entry>
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<entry>TC_BITS=8, PROVIDER_BITS=8, PROVIDER_OFFSET=0,
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MASK_BITS=8</entry>
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</row>
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<row>
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<entry>WIDE_TC_MARKS=No, HIGH_ROUTE_MARKS=Yes</entry>
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<entry>TC_BITS=8, PROVIDER_BITS=8, PROVIDER_OFFSET=8,
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MASK_BITS=8</entry>
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</row>
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<row>
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<entry>WIDE_TC_MARKS=Yes, HIGH_ROUTE_MARKS=No</entry>
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<entry>TC_BITS=14, PROVIDER_BITS=8, PROVIDER_OFFSET=0,
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MASK_BITS=16</entry>
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</row>
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<row>
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<entry>WIDE_TC_MARKS=Yes, HIGH_ROUTE_MARKS=Yes</entry>
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<entry>TC_BITS=14, PROVIDER_BITS=8, PROVIDER_OFFSET=16,
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MASK_BITS=16</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<para>The existence of both TC_BITS and MASK_BITS is owed to the way that
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WIDE_TC_MARKS was originally implemented. Note that TC_BITS is 14 rather
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than 16 when WIDE_TC_MARKS=Yes.</para>
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<para>Beginning with Shorewall 4.4.12, the field between MASK_BITS and
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PROVIDER_OFFSET can be used for any purpose you want.</para>
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<para>Beginning with Shorewall 4.4.13, the first unused bit on the left is
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used by Shorewall as an <firstterm>exclusion mark</firstterm>, allowing
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exclusion in CONTINUE, NONAT and ACCEPT+ rules.</para>
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<para>Beginning with Shorewall 4.4.26, WIDE_TC_MARKS and HIGH_ROUTE_MARKS
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are deprecated in favor of the options described above. The
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<command>shorewall update</command> (<command>shorewall6 update</command>)
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command will set the above options based on the settings of WIDE_TC_MARKS
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and HIGH_ROUTE_MARKS.</para>
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<para>In Shorewall 4.5.4, a <firstterm>TPROXY mark</firstterm> was added
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for TPROXY support. It is a single bit wide and is to the immediate left
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of the exclusion mark.</para>
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<para>The <firstterm>Event Mark</firstterm> bit was added in Shorewall
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4.5.19. It is to the immediate left of the TPROXY mark, and it need not
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fall within the 32-bit mark unless the <emphasis
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role="bold">reset</emphasis> command is used in the <emphasis
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role="bold">IfEvent</emphasis> action.</para>
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</section>
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<section id="Shorewall">
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<title>Shorewall-defined Chains in the Mangle Table</title>
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<para>Shorewall creates a set of chains in the mangle table to hold rules
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defined in your <firstterm>/etc/shorewall/tcrules</firstterm> file. As
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mentioned above, chains are like subroutines in the packet marking
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programming language. By placing all of your rules in subroutines,
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CONTINUE (which generates a Netfilter RETURN rule) can be used to stop
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processing your rules while still allowing following Shorewall-generated
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rules to be executed.</para>
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<variablelist>
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<varlistentry>
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<term>tcpre</term>
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<listitem>
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<para>PREROUTING rules.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>tcfor</term>
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<listitem>
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<para>FORWARD rules.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>tcout</term>
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<listitem>
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<para>OUTPUT rules.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>tcpost</term>
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<listitem>
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<para>POSTROUTING rules.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>Shorewall generates jumps to these chains from the built-in chains
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(PREROUTING, FORWARD, etc.).</para>
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</section>
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<section id="Examples">
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<title>An Example</title>
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<para>Here's the example (slightly expanded) from the comments at the top
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of the <filename>/etc/shorewall/tcrules</filename> file.</para>
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<programlisting>#ACTION SOURCE DEST PROTO PORT(S) CLIENT USER TEST LENGTH TOS
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# PORT(S)
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1 0.0.0.0/0 0.0.0.0/0 icmp echo-request #Rule 1
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1 0.0.0.0/0 0.0.0.0/0 icmp echo-reply #Rule 2
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1 $FW 0.0.0.0/0 icmp echo-request #Rule 3
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1 $FW 0.0.0.0/0 icmp echo-reply #Rule 4
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RESTORE 0.0.0.0/0 0.0.0.0/0 all - - - 0 #Rule 5
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CONTINUE 0.0.0.0/0 0.0.0.0/0 all - - - !0 #Rule 6
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4 0.0.0.0/0 0.0.0.0/0 ipp2p:all #Rule 7
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SAVE 0.0.0.0/0 0.0.0.0/0 all - - - !0 #Rule 8
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##LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE</programlisting>
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<para>Let's take a look at each rule:</para>
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<orderedlist>
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<listitem>
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<para>This straight-forward rule simply marks all 'ping' requests
|
|
passing through the firewall with mark value 1. Note that it does not
|
|
mark pings that originate on the firewall itself.</para>
|
|
</listitem>
|
|
|
|
<listitem>
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|
<para>Similarly, this rule marks 'ping' replies.</para>
|
|
</listitem>
|
|
|
|
<listitem>
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|
<para>This rule marks 'ping' requests that originate on the firewall.
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|
This rule and the next ones are part of the OUTPUT program.</para>
|
|
</listitem>
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|
|
|
<listitem>
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|
<para>Similarly, this rule marks 'ping' replies from the firewall
|
|
itself.</para>
|
|
</listitem>
|
|
|
|
<listitem>
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|
<para>Remember that even though 'ping' packets were marked in one of
|
|
the first two rules, they are still passed on to rule 5 (note that
|
|
packets marked by rules 3 and 4 are not processed by this rule since
|
|
it is in a different program). That rule moves the connection mark to
|
|
the packet mark, <emphasis>if the packet mark is still zero</emphasis>
|
|
(note the '0' in the TEST column). Without the '0' in the TEST column,
|
|
this rule would overwrite the marks assigned in the first two
|
|
rules.</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>If the packet mark is non-zero (note the '!0' in the TEST
|
|
column), then exit — The remaining rules will not be executed in this
|
|
case. The packet mark will be non-zero if this is a 'ping' packet, or
|
|
if the connection mark restored in rule 5 was non-zero.</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>The packet mark is still zero. This rule checks to see if this
|
|
is a P2P packet and if it is, the packet mark is set to 4.</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>If the packet mark is non-zero (meaning that it was set to 4 in
|
|
rule 7), then save the value (4) in the connection. The next time that
|
|
a packet from this same connection comes through this program, rule 6
|
|
will be executed and the P2P check will be avoided.</para>
|
|
</listitem>
|
|
</orderedlist>
|
|
</section>
|
|
|
|
<section id="Show">
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|
<title>Examining the Marking Programs on a Running System</title>
|
|
|
|
<para>You can see the tcrules in action using the <command>shorewall show
|
|
mangle</command> command.</para>
|
|
|
|
<para>The sample output from that command shown below has the following in
|
|
<filename>/etc/shorewall/providers</filename>:</para>
|
|
|
|
<programlisting>#NAME NUMBER MARK DUPLICATE INTERFACE GATEWAY OPTIONS COPY
|
|
Blarg 1 0x100 main eth3 206.124.146.254 track,balance br0,eth1
|
|
#LAST LINE -- ADD YOUR ENTRIES ABOVE THIS LINE -- DO NOT REMOVE
|
|
</programlisting>
|
|
|
|
<para>Here is <filename>/etc/shorewall/tcrules</filename>:</para>
|
|
|
|
<programlisting>#ACTION SOURCE DEST PROTO PORT(S) CLIENT USER TEST
|
|
# PORT(S)
|
|
1:110 192.168.0.0/22 eth3 #Our internal nets get priority
|
|
#over the server
|
|
1:130 206.124.146.177 eth3 tcp - 873
|
|
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
|
|
</programlisting>
|
|
|
|
<para>And here is <filename>/etc/shorewall/tcdevices</filename> and
|
|
<filename>/etc/shorewall/tcclasses</filename>:</para>
|
|
|
|
<programlisting>#INTERFACE IN-BANDWITH OUT-BANDWIDTH
|
|
eth3 1.3mbit 384kbit
|
|
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
|
|
|
|
#INTERFACE MARK RATE CEIL PRIORITY OPTIONS
|
|
eth3 10 full full 1 tcp-ack,tos-minimize-delay
|
|
eth3 20 9*full/10 9*full/10 2 default
|
|
eth3 30 6*full/10 6*full/10 3
|
|
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
|
|
</programlisting>
|
|
|
|
<para>I've annotated the following output with comments beginning with
|
|
"<<<<" and ending with ">>>>". This example uses
|
|
HIGH_ROUTE_MARKS=Yes and TC_EXPERT=No in
|
|
<filename>shorewall.conf</filename>.</para>
|
|
|
|
<programlisting>gateway:~ # <command>shorewall show mangle</command>
|
|
Shorewall 3.3.2 Mangle Table at gateway - Mon Oct 2 15:07:32 PDT 2006
|
|
|
|
Counters reset Mon Oct 2 07:49:52 PDT 2006
|
|
|
|
<<<< The PREROUTING Program >>>>
|
|
|
|
Chain PREROUTING (policy ACCEPT 409K packets, 122M bytes)
|
|
pkts bytes target prot opt in out source destination
|
|
|
|
<<<< Restore the provider mark from the connection, if any >>>>
|
|
|
|
185K 77M CONNMARK all -- * * 0.0.0.0/0 0.0.0.0/0 CONNMARK match !0x0/0xff00 CONNMARK restore mask 0xff00
|
|
|
|
<<<< If there is no mark in the connection and the packet came in on eth3, then jump to the <emphasis
|
|
role="bold">routemark</emphasis> chain
|
|
This rule is generated as a result of 'track' being specified in the providers file entry for eth3 >>>>
|
|
|
|
8804 1396K routemark all -- eth3 * 0.0.0.0/0 0.0.0.0/0 MARK match 0x0/0xff00
|
|
|
|
<<<< If the packet came in on eth3, jump the the <emphasis
|
|
role="bold">tcpre</emphasis> chain -- packets entering on a 'track'ed interface can have their mark set to zero there >>>>
|
|
|
|
102K 52M tcpre all -- eth3 * 0.0.0.0/0 0.0.0.0/0
|
|
|
|
<<<< Otherwise, jump to the tcpre chain if there is no current provider mark --
|
|
if we would have had TC_EXPERT=Yes, this jump would have been unconditional>>>>
|
|
|
|
215K 44M tcpre all -- * * 0.0.0.0/0 0.0.0.0/0 MARK match 0x0/0xff00
|
|
|
|
<<<< End of PREROUTING program >>>>
|
|
|
|
<<<< INPUT Program -- Shorewall generates the single rule here which turns off the provider mark in the packet after routing
|
|
The rule does that by logically ANDing the mark value with 0xff which will turn off all but the low-order 8 bits >>>>
|
|
|
|
Chain INPUT (policy ACCEPT 98238 packets, 16M bytes)
|
|
pkts bytes target prot opt in out source destination
|
|
98234 16M MARK all -- * * 0.0.0.0/0 0.0.0.0/0 MARK and 0xff
|
|
|
|
<<<< End of INPUT program >>>>
|
|
|
|
<<<< FORWARD Program -- Shorewall generates the first rule here which turns off the provider mark in the packet after routing >>>>
|
|
|
|
Chain FORWARD (policy ACCEPT 312K packets, 106M bytes)
|
|
pkts bytes target prot opt in out source destination
|
|
312K 106M MARK all -- * * 0.0.0.0/0 0.0.0.0/0 MARK and 0xff
|
|
|
|
<<<< Jump unconditionally to the <emphasis role="bold">tcfor</emphasis> chain >>>>
|
|
|
|
312K 106M tcfor all -- * * 0.0.0.0/0 0.0.0.0/0
|
|
|
|
<<<< End of FORWARD program >>>>
|
|
|
|
<<<< OUTPUT Program >>>>
|
|
|
|
Chain OUTPUT (policy ACCEPT 1462K packets, 396M bytes)
|
|
pkts bytes target prot opt in out source destination
|
|
|
|
<<<< Restore the provider mark from the connection -- this rule was generated by Shorewall because of the 'track' option >>>>
|
|
|
|
3339 615K CONNMARK all -- * * 0.0.0.0/0 0.0.0.0/0 CONNMARK match !0x0/0xff00 CONNMARK restore mask 0xff00
|
|
|
|
<<<< If there is no provider mark, then jump to the <emphasis
|
|
role="bold">tcout</emphasis> chain --
|
|
if we would have had TC_EXPERT=Yes, this jump would have been unconditional >>>>
|
|
|
|
92747 28M tcout all -- * * 0.0.0.0/0 0.0.0.0/0 MARK match 0x0/0xff00
|
|
|
|
<<<< End of FORWARD program >>>>
|
|
|
|
<<<< POSTROUTING Program -- Unconditionally jump to the <emphasis
|
|
role="bold">tcpost</emphasis> chain >>>>
|
|
|
|
Chain POSTROUTING (policy ACCEPT 407K packets, 135M bytes)
|
|
pkts bytes target prot opt in out source destination
|
|
407K 135M tcpost all -- * * 0.0.0.0/0 0.0.0.0/0
|
|
|
|
<<<< End of FORWARD program >>>>
|
|
|
|
Chain <emphasis role="bold">routemark</emphasis> (1 references)
|
|
pkts bytes target prot opt in out source destination
|
|
|
|
<<<< Set connection 'track' mark for packets coming in on eth3 >>>>
|
|
|
|
8804 1396K MARK all -- eth3 * 0.0.0.0/0 0.0.0.0/0 MARK or 0x100
|
|
|
|
<<<< Save any mark added above in the connection mark >>>>
|
|
|
|
8804 1396K CONNMARK all -- * * 0.0.0.0/0 0.0.0.0/0 MARK match !0x0/0xff00 CONNMARK save mask 0xff00
|
|
|
|
Chain <emphasis role="bold">tcfor</emphasis> (1 references)
|
|
pkts bytes target prot opt in out source destination
|
|
|
|
Chain <emphasis role="bold">tcout</emphasis> (1 references)
|
|
pkts bytes target prot opt in out source destination
|
|
|
|
Chain <emphasis role="bold">tcpost</emphasis> (1 references)
|
|
pkts bytes target prot opt in out source destination
|
|
|
|
<<<< The next two rules are the entries in the /etc/shorewall/tcrules file >>>>
|
|
|
|
65061 11M CLASSIFY all -- * eth3 192.168.0.0/22 0.0.0.0/0 CLASSIFY set 1:110
|
|
2224 2272K CLASSIFY tcp -- * eth3 206.124.146.177 0.0.0.0/0 tcp spt:873 CLASSIFY set 1:130
|
|
|
|
<<<< The following rules are generated by Shorewall and classify the traffic according to the marks in /etc/shorewall/classes >>>>
|
|
|
|
0 0 CLASSIFY all -- * eth3 0.0.0.0/0 0.0.0.0/0 MARK match 0xa/0xff CLASSIFY set 1:110
|
|
0 0 CLASSIFY all -- * eth3 0.0.0.0/0 0.0.0.0/0 MARK match 0x14/0xff CLASSIFY set 1:120
|
|
0 0 CLASSIFY all -- * eth3 0.0.0.0/0 0.0.0.0/0 MARK match 0x1e/0xff CLASSIFY set 1:130
|
|
|
|
Chain <emphasis role="bold">tcpre</emphasis> (2 references)
|
|
pkts bytes target prot opt in out source destination
|
|
gateway:~ #</programlisting>
|
|
</section>
|
|
</article>
|