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341 lines
14 KiB
XML
341 lines
14 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<article>
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<!--$Id$-->
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<articleinfo>
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<title>Traffic Shaping/Control</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>2004-07-14</pubdate>
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<copyright>
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<year>2001-2004</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 License</ulink></quote>.</para>
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</legalnotice>
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</articleinfo>
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<section>
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<title>Introduction</title>
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<para>Shorewall does not do any type of Traffic Shaping/Bandwidth
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management itself but it does contain some facilities to intergrate with
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traffic shaping/control solutions. In order to use traffic shaping with
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Shorewall, it is essential that you get a copy of the <ulink
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url="http://ds9a.nl/lartc">Linux Advanced Routing and Shaping HOWTO</ulink>,
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version 0.3.0 or later or <ulink
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url="http://www.tldp.org/HOWTO/Traffic-Control-HOWTO/">The Traffic Control
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HOWTO</ulink>. It is also necessary to be running Linux Kernel 2.4.18 or
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later. Shorewall traffic shaping support consists of the following:</para>
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<itemizedlist>
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<listitem>
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<para>A new <emphasis role="bold">TC_ENABLED</emphasis> parameter in
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/etc/shorewall.conf.</para>
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</listitem>
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<listitem>
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<para>A new <emphasis role="bold">CLEAR_TC</emphasis> parameter in
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/etc/shorewall.conf (Added in Shorewall 1.3.13). When Traffic Shaping
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is enabled (TC_ENABLED=Yes), the setting of this variable determines
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whether Shorewall clears the traffic shaping configuration during
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Shorewall [re]start and Shorewall stop.</para>
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</listitem>
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<listitem>
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<para><emphasis role="bold">/etc/shorewall/tcrules</emphasis> - A file
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where you can specify firewall marking of packets. The firewall mark
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value may be used to classify packets for traffic shaping/control.</para>
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</listitem>
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<listitem>
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<para><emphasis role="bold">/etc/shorewall/tcstart </emphasis>- A
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user-supplied file that is sourced by Shorewall during <quote>shorewall
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start</quote> and which you can use to define your traffic shaping
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disciplines and classes. I have provided a <ulink
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url="ftp://ftp.shorewall.net/pub/shorewall/cbq">sample</ulink> that
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does table-driven CBQ shaping but if you read the traffic shaping
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sections of the HOWTO mentioned above, you can probably code your own
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faster than you can learn how to use my sample. I personally use
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<ulink url="http://luxik.cdi.cz/%7Edevik/qos/htb/">HTB</ulink> (see
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below). HTB support may eventually become an integral part of
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Shorewall since HTB is a lot simpler and better-documented than CBQ.
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As of 2.4.20, HTB is a standard part of the kernel but iproute2 must
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be patched in order to use it.</para>
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<para>In tcstart, when you want to run the <quote>tc</quote> utility,
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use the run_tc function supplied by shorewall if you want tc errors to
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stop the firewall.</para>
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<para>You can generally use off-the-shelf traffic shaping scripts by
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simply copying them to /etc/shorewall/tcstart. I use <ulink
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url="http://lartc.org/wondershaper/">The Wonder Shaper </ulink>(HTB
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version) that way (i.e., I just copied wshaper.htb to
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/etc/shorewall/tcstart and modified it according to the Wonder Shaper
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README). <emphasis role="bold">WARNING</emphasis>: If you use use
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Masquerading or SNAT (i.e., you only have one external IP address)
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then listing internal hosts in the NOPRIOHOSTSRC variable in the
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wshaper[.htb] script won't work. Traffic shaping occurs after SNAT
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has already been applied so when traffic shaping happens, all outbound
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traffic will have as a source address the IP addresss of your
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firewall's external interface.</para>
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</listitem>
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<listitem>
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<para><emphasis role="bold">/etc/shorewall/tcclear</emphasis> - A
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user-supplied file that is sourced by Shorewall when it is clearing
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traffic shaping. This file is normally not required as Shorewall's
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method of clearing qdisc and filter definitions is pretty general.</para>
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</listitem>
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</itemizedlist>
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<para>Shorewall allows you to start traffic shaping when Shorewall itself
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starts or it allows you to bring up traffic shaping when you bring up your
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interfaces.</para>
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<para>To start traffic shaping when Shorewall starts:</para>
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<orderedlist>
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<listitem>
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<para>Set TC_ENABLED=Yes and CLEAR_TC=Yes</para>
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</listitem>
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<listitem>
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<para>Supply an /etc/shorewall/tcstart script to configure your
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traffic shaping rules.</para>
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</listitem>
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<listitem>
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<para>Optionally supply an /etc/shorewall/tcclear script to stop
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traffic shaping. That is usually unnecessary.</para>
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</listitem>
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<listitem>
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<para>If your tcstart script uses the <quote>fwmark</quote>
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classifier, you can mark packets using entries in
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/etc/shorewall/tcrules.</para>
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</listitem>
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</orderedlist>
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<para>To start traffic shaping when you bring up your network interfaces,
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you will have to arrange for your traffic shaping configuration script to
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be run at that time. How you do that is distribution dependent and will
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not be covered here. You then should:</para>
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<orderedlist>
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<listitem>
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<para>Set TC_ENABLED=Yes and CLEAR_TC=No</para>
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</listitem>
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<listitem>
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<para>Do not supply /etc/shorewall/tcstart or /etc/shorewall/tcclear
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scripts.</para>
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</listitem>
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<listitem>
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<para>If your tcstart script uses the <quote>fwmark</quote>
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classifier, you can mark packets using entries in
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/etc/shorewall/tcrules.</para>
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</listitem>
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</orderedlist>
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</section>
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<section>
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<title>Kernel Configuration</title>
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<para>This screen shot show how I've configured QoS in my Kernel:<graphic
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align="center" fileref="images/QoS.png" /></para>
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</section>
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<section>
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<title>/etc/shorewall/tcrules</title>
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<para>The fwmark classifier provides a convenient way to classify packets
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for traffic shaping. The /etc/shorewall/tcrules file provides a means for
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specifying these marks in a tabular fashion.</para>
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<para>Normally, packet marking occurs in the PREROUTING chain before any
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address rewriting takes place. This makes it impossible to mark inbound
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packets based on their destination address when SNAT or Masquerading are
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being used. Beginning with Shorewall 1.3.12, you can cause packet marking
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to occur in the FORWARD chain by using the MARK_IN_FORWARD_CHAIN option in
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shorewall.conf.</para>
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<para>Columns in the file are as follows:</para>
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<itemizedlist>
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<listitem>
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<para>MARK - Specifies the mark value is to be assigned in case of a
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match. This is an integer in the range 1-255. Beginning with Shorewall
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version 1.3.14, this value may be optionally followed by
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<quote>:</quote> and either <quote>F</quote> or <quote>P</quote> to
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designate that the marking will occur in the FORWARD or PREROUTING
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chains respectively. If this additional specification is omitted, the
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chain used to mark packets will be determined by the setting of the
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MARK_IN_FORWARD_CHAIN option in shorewall.conf.</para>
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</listitem>
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<listitem>
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<para>SOURCE - The source of the packet. If the packet originates on
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the firewall, place <quote>fw</quote> in this column. Otherwise, this
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is a comma-separated list of interface names, IP addresses, MAC
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addresses in Shorewall Format and/or Subnets.</para>
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<para>Examples <programlisting> eth0
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192.168.2.4,192.168.1.0/24</programlisting></para>
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</listitem>
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<listitem>
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<para>DEST -- Destination of the packet. Comma-separated list of IP
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addresses and/or subnets.</para>
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</listitem>
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<listitem>
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<para>PROTO - Protocol - Must be the name of a protocol from
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/etc/protocol, a number or <quote>all</quote></para>
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</listitem>
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<listitem>
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<para>PORT(S) - Destination Ports. A comma-separated list of Port
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names (from /etc/services), port numbers or port ranges (e.g., 21:22);
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if the protocol is <quote>icmp</quote>, this column is interpreted as
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the destination icmp type(s).</para>
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</listitem>
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<listitem>
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<para>CLIENT PORT(S) - (Optional) Port(s) used by the client. If
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omitted, any source port is acceptable. Specified as a comma-separate
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list of port names, port numbers or port ranges.</para>
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</listitem>
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<listitem>
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<para>USER (Added in Shorewall version 1.4.10) - (Optional) This
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column may only be non-empty if the SOURCE is the firewall itself.
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When this column is non-empty, the rule applies only if the program
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generating the output is running under the effective user and/or
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group. It may contain :</para>
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<para>[<user name or number>]:[<group name or number>]</para>
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<para>The colon is optionnal when specifying only a user.</para>
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<para>Examples : john: / john / :users / john:users</para>
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</listitem>
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</itemizedlist>
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<example>
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<title></title>
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<para>All packets arriving on eth1 should be marked with 1. All packets
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arriving on eth2 and eth3 should be marked with 2. All packets
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originating on the firewall itself should be marked with 3.</para>
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<programlisting>#MARK SOURCE DESTINATION PROTOCOL USER/GROUP
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1 eth1 0.0.0.0/0 all
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2 eth2 0.0.0.0/0 all
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2 eth3 0.0.0.0/0 all
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3 fw 0.0.0.0/0 all</programlisting>
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</example>
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<example>
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<title></title>
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<para>All GRE (protocol 47) packets not originating on the firewall and
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destined for 155.186.235.151 should be marked with 12.</para>
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<programlisting>#MARK SOURCE DESTINATION PROTOCOL USER/GROUP
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12 0.0.0.0/0 155.182.235.151 47</programlisting>
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</example>
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<example>
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<title></title>
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<para>All SSH packets originating in 192.168.1.0/24 and destined for
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155.186.235.151 should be marked with 22.</para>
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<programlisting>#MARK SOURCE DESTINATION PROTOCOL USER/GROUP
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22 192.168.1.0/24 155.182.235.151 tcp 22</programlisting>
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</example>
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</section>
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<section>
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<title>My Current Setup</title>
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<para>I am currently using the HTB version of <ulink
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url="http://lartc.org/wondershaper/">The Wonder Shaper </ulink>(I just
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copied wshaper.htb to /etc/shorewall/tcstart and modified it as shown in
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the Wondershaper README). WonderShaper DOES NOT USE THE
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/etc/shorewall/tcrules file.</para>
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</section>
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<section>
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<title>My Old Setup</title>
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<para>I have also run with the following set of hand-crafted rules in my
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<emphasis role="bold">/etc/shorewall/tcstart</emphasis> file.</para>
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<blockquote>
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<programlisting>run_tc qdisc add dev eth0 root handle 1: htb default 30
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run_tc class add dev eth0 parent 1: classid 1:1 htb rate 384kbit burst 15k
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echo <quote> Added Top Level Class -- rate 384kbit</quote>
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run_tc class add dev eth0 parent 1:1 classid 1:10 htb rate 140kbit ceil 384kbit burst 15k prio 1
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run_tc class add dev eth0 parent 1:1 classid 1:20 htb rate 224kbit ceil 384kbit burst 15k prio 0
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run_tc class add dev eth0 parent 1:1 classid 1:30 htb rate 20kbit ceil 384kbit burst 15k quantum 1500 prio 1
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echo <quote> Added Second Level Classes -- rates 140kbit, 224kbit, 20kbit</quote>
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run_tc qdisc add dev eth0 parent 1:10 pfifo limit 5run_tc qdisc add dev eth0 parent 1:20 pfifo limit 10
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run_tc qdisc add dev eth0 parent 1:30 pfifo limit 5
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echo <quote> Enabled PFIFO on Second Level Classes</quote>
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run_tc filter add dev eth0 protocol ip parent 1:0 prio 1 handle 1 fw classid 1:10
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run_tc filter add dev eth0 protocol ip parent 1:0 prio 0 handle 2 fw classid 1:20
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run_tc filter add dev eth0 protocol ip parent 1:0 prio 1 handle 3 fw classid 1:30
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echo <quote> Defined fwmark filters</quote>
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</programlisting>
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</blockquote>
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<para>My tcrules file that went with this tcstart file is shown in Example
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1 above. When I was using these rules:</para>
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<orderedlist>
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<listitem>
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<para>I wanted to allow up to 140kbits/second for traffic outbound
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from my DMZ (eth1 -- note that the ceiling is set to 384kbit so
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outbound DMZ traffic can use all available bandwidth if there is no
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traffic from the local systems or from my laptop or firewall).</para>
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</listitem>
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<listitem>
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<para>My laptop (which at that time connected via eth3) and local
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systems (eth2) could use up to 224kbits/second.</para>
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</listitem>
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<listitem>
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<para>My firewall could use up to 20kbits/second.</para>
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</listitem>
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</orderedlist>
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<para>Once www.shorewall.net was moved off-site, I no longer needed these
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shaping rules and The Wonder Shaper does all that I now require.</para>
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</section>
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</article> |