mirror of
https://gitlab.com/shorewall/code.git
synced 2024-11-27 01:53:27 +01:00
228 lines
9.4 KiB
XML
228 lines
9.4 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
|
|
<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
|
|
"http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd">
|
|
<article>
|
|
<!--$Id$-->
|
|
|
|
<articleinfo>
|
|
<title>Simple Traffic Shaping/Control</title>
|
|
|
|
<authorgroup>
|
|
<author>
|
|
<firstname>Tom</firstname>
|
|
|
|
<surname>Eastep</surname>
|
|
</author>
|
|
</authorgroup>
|
|
|
|
<pubdate><?dbtimestamp format="Y/m/d"?></pubdate>
|
|
|
|
<copyright>
|
|
<year>2009</year>
|
|
|
|
<year>2010</year>
|
|
|
|
<holder>Thomas M. Eastep</holder>
|
|
</copyright>
|
|
|
|
<legalnotice>
|
|
<para>Permission is granted to copy, distribute and/or modify this
|
|
document under the terms of the GNU Free Documentation License, Version
|
|
1.2 or any later version published by the Free Software Foundation; with
|
|
no Invariant Sections, with no Front-Cover, and with no Back-Cover
|
|
Texts. A copy of the license is included in the section entitled
|
|
<quote><ulink url="GnuCopyright.htm">GNU Free Documentation
|
|
License</ulink></quote>.</para>
|
|
</legalnotice>
|
|
</articleinfo>
|
|
|
|
<section>
|
|
<title>Introduction</title>
|
|
|
|
<para>Traffic shaping and control was originally introduced into Shorewall
|
|
in version 2.2.5. That facility was based on Arne Bernin's
|
|
<firstterm>tc4shorewall</firstterm> and is generally felt to be complex
|
|
and difficult to use.</para>
|
|
|
|
<para>In Shorewall 4.4.6, a second traffic shaping facility that is simple
|
|
to understand and to configure was introduced. This newer facility is
|
|
described in this document while the original facility is documented in
|
|
<ulink url="traffic_shaping.htm">Complex Traffic
|
|
Shaping/Control</ulink>.</para>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Enabling Simple Traffic Shaping</title>
|
|
|
|
<para>Simple traffic shaping is enabled by setting TC_ENABLED=Simple in
|
|
<ulink url="manpages/shorewall.conf.html">shorewall.conf</ulink>(5). You
|
|
then add an entry for your external interface to <ulink
|
|
url="manpages/shorewall-tcinterfaces.html">shorewall-tcinterfaces</ulink>(5)
|
|
(<filename>/etc/shorewall/tcinterfaces</filename>).</para>
|
|
|
|
<para>Assuming that your external interface is eth0:</para>
|
|
|
|
<programlisting>#INTERFACE TYPE IN-BANDWIDTH
|
|
eth0 External</programlisting>
|
|
|
|
<para>With this simple configuration, packets to be sent through interface
|
|
eth0 will be assigned to a priority band based on the value of their TOS
|
|
field:</para>
|
|
|
|
<programlisting>TOS Bits Means Linux Priority BAND
|
|
------------------------------------------------------------
|
|
0x0 0 Normal Service 0 Best Effort 2
|
|
0x2 1 Minimize Monetary Cost 1 Filler 3
|
|
0x4 2 Maximize Reliability 0 Best Effort 2
|
|
0x6 3 mmc+mr 0 Best Effort 2
|
|
0x8 4 Maximize Throughput 2 Bulk 3
|
|
0xa 5 mmc+mt 2 Bulk 3
|
|
0xc 6 mr+mt 2 Bulk 3
|
|
0xe 7 mmc+mr+mt 2 Bulk 3
|
|
0x10 8 Minimize Delay 6 Interactive 1
|
|
0x12 9 mmc+md 6 Interactive 1
|
|
0x14 10 mr+md 6 Interactive 1
|
|
0x16 11 mmc+mr+md 6 Interactive 1
|
|
0x18 12 mt+md 4 Int. Bulk 2
|
|
0x1a 13 mmc+mt+md 4 Int. Bulk 2
|
|
0x1c 14 mr+mt+md 4 Int. Bulk 2
|
|
0x1e 15 mmc+mr+mt+md 4 Int. Bulk 2</programlisting>
|
|
|
|
<para>When dequeueing, band 1 is tried first and only if it did not
|
|
deliver a packet does the system try band 2, and so onwards. Maximum
|
|
reliability packets should therefore go to band 1, minimum delay to band 2
|
|
and the rest to band 3.</para>
|
|
|
|
<note>
|
|
<para>If you run both an IPv4 and an IPv6 firewall on your system, you
|
|
should define each interface in only one of the two
|
|
configurations.</para>
|
|
</note>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Customizing Simple Traffic Shaping</title>
|
|
|
|
<para>The default mapping of TOS to bands can be changed using the
|
|
TC_PRIOMAP setting in <ulink
|
|
url="manpages/shorewall.conf.html">shorewall.conf</ulink>(5). The default
|
|
setting of this option is:</para>
|
|
|
|
<programlisting>TC_PRIOMAP="2 3 3 3 2 3 1 1 2 2 2 2 2 2 2 2"</programlisting>
|
|
|
|
<para>These entries map Linux Priority to priority BAND. So only entries
|
|
0, 1, 2, 4 and 6 in the map are relevant to TOS->BAND mapping.</para>
|
|
|
|
<para>Further customizations can be defined in <ulink
|
|
url="manpages/shorewall-tcpri.html">shorewall-tcpri</ulink>(5)
|
|
(<filename>/etc/shorewall/tcpri</filename>). Using that file, you
|
|
can:</para>
|
|
|
|
<orderedlist>
|
|
<listitem>
|
|
<para>Assign traffic entering the firewall on a particular interface
|
|
to a specific priority band:</para>
|
|
|
|
<programlisting>#BAND PROTO PORT(S) ADDRESS INTERFACE HELPER
|
|
2 - - - eth1</programlisting>
|
|
|
|
<para>In this example, traffic from eth1 will be assigned to priority
|
|
band 2.</para>
|
|
|
|
<note>
|
|
<para>When an INTERFACE is specified, the PROTO, PORT(S) and ADDRESS
|
|
column must contain '-'.</para>
|
|
</note>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>Assign traffic from a particular IP address to a specific
|
|
priority band:</para>
|
|
|
|
<programlisting>#BAND PROTO PORT(S) ADDRESS INTERFACE HELPER
|
|
1 - - 192.168.1.44</programlisting>
|
|
|
|
<para>In this example, traffic from 192.168.1.44 will be assigned to
|
|
priority band 1.</para>
|
|
|
|
<note>
|
|
<para>When an ADDRESS is specified, the PROTO, PORT(S) and INTERFACE
|
|
columns must be empty.</para>
|
|
</note>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>Assign traffic to/from a particular application to a specific
|
|
priority band:</para>
|
|
|
|
<programlisting>#BAND PROTO PORT(S) ADDRESS INTERFACE HELPER
|
|
1 udp 1194</programlisting>
|
|
|
|
<para>In that example, OpenVPN traffic is assigned to priority band
|
|
1.</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>Assign traffic that uses a particular Netfilter helper to a
|
|
particular priority band:</para>
|
|
|
|
<programlisting>#BAND PROTO PORT(S) ADDRESS INTERFACE HELPER
|
|
1 - - - - sip</programlisting>
|
|
|
|
<para>In this example, SIP and associated RTP traffic will be assigned
|
|
to priority band 1 (assuming that the nf_conntrack_sip helper is
|
|
loaded).</para>
|
|
</listitem>
|
|
</orderedlist>
|
|
|
|
<para>It is suggested that entries specifying an INTERFACE be placed the
|
|
top of the file. That way, the band assigned to a particular packet will
|
|
be the <emphasis role="bold">last</emphasis> entry matched by the packet.
|
|
Packets which match no entry in <ulink
|
|
url="manpages/shorewall-tcpri.html">shorewall-tcpri</ulink>(5) are
|
|
assigned to priority bands using their TOS field as previously
|
|
described.</para>
|
|
|
|
<para>One cause of high latency on interactive traffic can be that queues
|
|
are building up at your ISP's gateway router. If you suspect that is
|
|
happening in your case, you can try to eliminate the problem by using the
|
|
IN-BANDWIDTH setting in <ulink
|
|
url="manpages/shorewall-tcinterfaces.html">shorewall-tcinterfaces</ulink>(5).
|
|
The contents of the column are a <replaceable>rate</replaceable>. For
|
|
defining the rate, use <emphasis role="bold">kbit</emphasis> or <emphasis
|
|
role="bold">kbps</emphasis> (for Kilobytes per second) and make sure there
|
|
is NO space between the number and the unit (it is 100kbit not 100 kbit).
|
|
<emphasis role="bold">mbit</emphasis>, <emphasis
|
|
role="bold">mbps</emphasis> or a raw number (which means bytes) can be
|
|
used, but note that only integer numbers are supported (0.5 is not valid).
|
|
To pick an appropriate setting, we recommend that you start by setting
|
|
IN-BANDWIDTH significantly below your measured download bandwidth (20% or
|
|
so). While downloading, measure the ping response time from the firewall
|
|
to the upstream router as you gradually increase the setting. The optimal
|
|
setting is at the point beyond which the ping time increases sharply as
|
|
you increase the setting.</para>
|
|
|
|
<para>Simple Traffic Shaping is only appropriate on interfaces where
|
|
output queuing occurs. As a consequence, you usually only use it on
|
|
extermal interfaces. There are cases where you may need to use it on an
|
|
internal interface (a VPN interface, for example). If so, just add an
|
|
entry to <ulink
|
|
url="manpages/shorewall-tcinterfaces.html">shorewall-tcinterfaces</ulink>(5):</para>
|
|
|
|
<programlisting>#INTERFACE TYPE IN-BANDWIDTH
|
|
tun0 Internal</programlisting>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Additional Reading</title>
|
|
|
|
<para>The PRIO(8) (tc-prio) manpage has additional information on the
|
|
facility that Shorewall Simple Traffic Shaping is based on.</para>
|
|
|
|
<caution>
|
|
<para>Please note that Shorewall numbers the bands 1-3 whereas PRIO(8)
|
|
refers to them as bands 0-2.</para>
|
|
</caution>
|
|
</section>
|
|
</article>
|