Try to make zone definition clearer in the Introduction

git-svn-id: https://shorewall.svn.sourceforge.net/svnroot/shorewall/trunk@3915 fbd18981-670d-0410-9b5c-8dc0c1a9a2bb
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teastep 2006-05-16 14:00:10 +00:00
parent 82413defc5
commit 317e5e74ca

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@ -130,12 +130,47 @@ dmz Demilitarized Zone</programlisting>
<para>Zones are declared and given a type in the <ulink
url="Documentation.htm#Zones"><filename
class="directory">/etc/shorewall/</filename><filename>zones</filename></ulink>
file.</para>
file.Here is the <ulink url="Documentation.htm#Zones"><filename
class="directory">/etc/shorewall/</filename><filename>zones</filename></ulink>
file from the three-interface sample:</para>
<programlisting>#ZONE TYPE OPTIONS IN OUT
# OPTIONS OPTIONS
fw firewall
net ipv4
loc ipv4
dmz ipv4
#LAST LINE - ADD YOUR ENTRIES ABOVE THIS ONE - DO NOT REMOVE</programlisting>
<para>Note that Shorewall recognizes the firewall system as its own zone.
The name of the zone designating the firewall itself is stored in the
shell variable $<firstterm>FW</firstterm> which may be used throughout the
Shorewall configuration to refer to the firewall zone.</para>
The name of the zone designating the firewall itself (usually 'fw' as
shown in the above file) is stored in the shell variable
$<firstterm>FW</firstterm> which may be used throughout the Shorewall
configuration to refer to the firewall zone.</para>
<para>The simplest way to define the hosts in a zone is to associate the
zone with a network interface using the <ulink
url="Documentation.htm#Interfaces"><filename>/etc/shorewall/interfaces</filename></ulink>
file. In the three-interface sample, the three zones are defined using
that file as follows:</para>
<programlisting>#ZONE INTERFACE BROADCAST OPTIONS
net eth0 detect dhcp,routefilter,norfc1918
loc eth1 detect
dmz eth2 detect</programlisting>
<para>The above file defines the net zone as all IPv4 hosts interfacing to
the firewall through eth0, the loc zone as all IPv4 hosts interfacing
through eth1 and the dmz as all IPv4 hosts interfacing through eth2. It is
important to note that the composition of a zone is defined in terms of a
combination of addresses <emphasis role="bold">and</emphasis> interfaces.
When using the <ulink
url="Documentation.htm#Interfaces"><filename>/etc/shorewall/interfaces</filename></ulink>
file to define a zone, all addresses are included; when you want to define
a zone that contains a limited subset of the IPv4 address space, you use
the <ulink
url="Documentation.htm#Hosts"><filename>/etc/shorewall/hosts</filename></ulink>
file.</para>
<para>Rules about what traffic to allow and what traffic to deny are
expressed in terms of zones. <itemizedlist spacing="compact">
@ -232,21 +267,6 @@ $FW net ACCEPT</programlisting> The above policy will:
</listitem>
</itemizedlist></para>
<para>The simplest way to define the hosts in a zone is to associate the
zone with a network interface using the <ulink
url="Documentation.htm#Interfaces"><filename>/etc/shorewall/interfaces</filename></ulink>
file. In the three-interface sample, the three zones are defined using
that file as follows:</para>
<programlisting>#ZONE INTERFACE BROADCAST OPTIONS
net eth0 detect dhcp,routefilter,norfc1918
loc eth1 detect
dmz eth2 detect</programlisting>
<para>The above file defines the net zone as all hosts interfacing to the
firewall through eth0, the loc zone as all hosts interfacing through eth1
and the dmz as all hosts interfacing through eth2.</para>
<para>To illustrate how rules provide exceptions to policies, suppose that
you have the polcies listed above but you want to be able to connect to
your firewall from the internet using Secure Shell (SSH). Recall that SSH