mirror of
https://gitlab.com/shorewall/code.git
synced 2024-11-24 16:43:21 +01:00
92 lines
3.1 KiB
XML
92 lines
3.1 KiB
XML
|
<?xml version="1.0" encoding="UTF-8"?>
|
||
|
|
<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
|
||
|
|
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
|
||
|
|
<article id="ECN">
|
||
|
|
<!--$Id$-->
|
||
|
|
|
||
|
|
<articleinfo>
|
||
|
|
<title>ECN</title>
|
||
|
|
|
||
|
|
<authorgroup>
|
||
|
|
<author>
|
||
|
|
<firstname>Tom</firstname>
|
||
|
|
|
||
|
|
<surname>Eastep</surname>
|
||
|
|
</author>
|
||
|
|
</authorgroup>
|
||
|
|
|
||
|
|
<pubdate>2003-03-28</pubdate>
|
||
|
|
|
||
|
|
<copyright>
|
||
|
|
<year>2001</year>
|
||
|
|
|
||
|
|
<year>2002</year>
|
||
|
|
|
||
|
|
<year>2003</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>Explicit Congestion Notification (ECN)</title>
|
||
|
|
|
||
|
|
<para>Explicit Congestion Notification (ECN) is described in RFC 3168 and
|
||
|
|
is a proposed internet standard. Unfortunately, not all sites support ECN
|
||
|
|
and when a TCP connection offering ECN is sent to sites that don't
|
||
|
|
support it, the result is often that the connection request is ignored.</para>
|
||
|
|
|
||
|
|
<para>To allow ECN to be used, Shorewall allows you to enable ECN on your
|
||
|
|
Linux systems then disable it in your firewall when the destination
|
||
|
|
matches a list that you create (the /etc/shorewall/ecn file).</para>
|
||
|
|
|
||
|
|
<para>You enable ECN by</para>
|
||
|
|
|
||
|
|
<programlisting>echo 1 > /proc/sys/net/ipv4/tcp_ecn</programlisting>
|
||
|
|
|
||
|
|
<para>You must arrange for that command to be executed at system boot.
|
||
|
|
Most distributions have a method for doing that -- on RedHat, you make an
|
||
|
|
entry in /etc/sysctl.conf.</para>
|
||
|
|
|
||
|
|
<programlisting>net.ipv4.tcp_ecn = 1</programlisting>
|
||
|
|
|
||
|
|
<para>Entries in /etc/shorewall/ecn have two columns as follows:</para>
|
||
|
|
|
||
|
|
<variablelist>
|
||
|
|
<varlistentry>
|
||
|
|
<term>INTERFACE</term>
|
||
|
|
|
||
|
|
<listitem>
|
||
|
|
<para>The name of an interface on your system</para>
|
||
|
|
</listitem>
|
||
|
|
</varlistentry>
|
||
|
|
|
||
|
|
<varlistentry>
|
||
|
|
<term>HOST(S)</term>
|
||
|
|
|
||
|
|
<listitem>
|
||
|
|
<para>An address (host or subnet) of a system or group of systems
|
||
|
|
accessed through the interface in the first column. You may include
|
||
|
|
a comma-separated list of such addresses in this column.</para>
|
||
|
|
</listitem>
|
||
|
|
</varlistentry>
|
||
|
|
</variablelist>
|
||
|
|
|
||
|
|
<example>
|
||
|
|
<title>Your external interface is eth0 and you want to disable ECN for
|
||
|
|
tcp connections to 192.0.2.0/24:</title>
|
||
|
|
|
||
|
|
<para><table><title>/etc/shorewall/ecn</title><tgroup cols="2"><thead><row><entry
|
||
|
|
align="center">INTERFACE</entry><entry align="center">HOST(S)</entry></row></thead><tbody><row><entry>eth0</entry><entry>192.0.2.0/24</entry></row></tbody></tgroup></table></para>
|
||
|
|
</example>
|
||
|
|
</section>
|
||
|
|
</article>
|