mirror of
https://gitlab.com/shorewall/code.git
synced 2024-11-27 01:53:27 +01:00
afee989ee5
git-svn-id: https://shorewall.svn.sourceforge.net/svnroot/shorewall/trunk@1099 fbd18981-670d-0410-9b5c-8dc0c1a9a2bb
194 lines
9.2 KiB
XML
194 lines
9.2 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="usefull_links">
|
|
<!--$Id$-->
|
|
|
|
<articleinfo>
|
|
<title>Introduction</title>
|
|
|
|
<author>
|
|
<firstname>Tom</firstname>
|
|
|
|
<surname>Eastep</surname>
|
|
</author>
|
|
|
|
<pubdate>2004-01-26</pubdate>
|
|
|
|
<copyright>
|
|
<year>2003-2004</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 type="" url="Copyright.htm">GNU Free Documentation License</ulink></quote>.</para>
|
|
</legalnotice>
|
|
</articleinfo>
|
|
|
|
<section>
|
|
<title>Introduction</title>
|
|
|
|
<para>The information in this document applies only to 1.4.x releases of
|
|
Shorewall.</para>
|
|
|
|
<section>
|
|
<title>Glossary</title>
|
|
|
|
<itemizedlist>
|
|
<listitem>
|
|
<para><ulink url="http://www.netfilter.org">Netfilter</ulink> - the
|
|
packet filter facility built into the 2.4 and later Linux kernels.</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>ipchains - the packet filter facility built into the 2.2 Linux
|
|
kernels. Also the name of the utility program used to configure and
|
|
control that facility. Netfilter can be used in ipchains
|
|
compatibility mode.</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>iptables - the utility program used to configure and control
|
|
Netfilter. The term <quote>iptables</quote> is often used to refer
|
|
to the combination of iptables+Netfilter (with Netfilter not in
|
|
ipchains compatibility mode).</para>
|
|
</listitem>
|
|
</itemizedlist>
|
|
</section>
|
|
|
|
<section>
|
|
<title>What is Shorewall?</title>
|
|
|
|
<para>The Shoreline Firewall, more commonly known as <quote>Shorewall</quote>,
|
|
is high-level tool for configuring Netfilter. You describe your
|
|
firewall/gateway requirements using entries in a set of configuration
|
|
files. Shorewall reads those configuration files and with the help of
|
|
the iptables utility, Shorewall configures Netfilter to match your
|
|
requirements. Shorewall can be used on a dedicated firewall system, a
|
|
multi-function gateway/router/server or on a standalone GNU/Linux
|
|
system. Shorewall does not use Netfilter's ipchains compatibility
|
|
mode and can thus take advantage of Netfilter's connection state
|
|
tracking capabilities.</para>
|
|
|
|
<para>Shorewall is not a daemon. Once Shorewall has configured
|
|
Netfilter, it's job is complete although the <ulink
|
|
url="starting_and_stopping_shorewall.htm">/sbin/shorewall program can be
|
|
used at any time to monitor the Netfilter firewall</ulink>.</para>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Getting Started with Shorewall</title>
|
|
|
|
<para>New to Shorewall? Start by selecting the <ulink
|
|
url="shorewall_quickstart_guide.htm">QuickStart Guide</ulink> that most
|
|
closely match your environment and follow the step by step instructions.</para>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Looking for Information?</title>
|
|
|
|
<para>The <ulink url="Documentation_Index.html">Documentation Index</ulink>
|
|
is a good place to start.</para>
|
|
</section>
|
|
</section>
|
|
|
|
<section>
|
|
<title>Shorewall Concepts</title>
|
|
|
|
<para>The configuration files for Shorewall are contained in the directory
|
|
<filename class="directory">/etc/shorewall</filename> -- for simple
|
|
setups, you will only need to deal with a few of them.</para>
|
|
|
|
<para>Shorewall views the network where it is running as being composed of
|
|
a set of zones. In the <ulink url="three-interface.htm">three-interface
|
|
sample configuration</ulink> for example, the following zone names are
|
|
used: <informaltable frame="all" pgwide="0"><tgroup align="left" cols="2"><thead
|
|
valign="middle"><row valign="middle"><entry align="left">Name</entry><entry
|
|
align="left">Description</entry></row></thead><tbody valign="middle"><row
|
|
valign="middle"><entry align="left"><varname>net</varname></entry><entry
|
|
align="left">The Internet</entry></row><row valign="middle"><entry
|
|
align="left"><varname>loc</varname></entry><entry align="left">Your Local
|
|
Network</entry></row><row valign="middle"><entry align="left"><varname>dmz</varname></entry><entry
|
|
align="left">Demilitarized Zone</entry></row></tbody></tgroup></informaltable>Zones
|
|
are defined in the <ulink url="Documentation.htm#Zones"><filename
|
|
class="directory">/etc/shorewall/</filename><filename>zones</filename></ulink>
|
|
file.</para>
|
|
|
|
<para>Shorewall also recognizes the firewall system as its own zone - by
|
|
default, the firewall itself is known as <emphasis role="bold"><varname>fw</varname></emphasis>.</para>
|
|
|
|
<para>Rules about what traffic to allow and what traffic to deny are
|
|
expressed in terms of zones. <itemizedlist spacing="compact"><listitem><para>You
|
|
express your default policy for connections from one zone to another zone
|
|
in the <ulink url="Documentation.htm#Policy"><filename class="directory">/etc/shorewall/</filename><filename>policy</filename></ulink>
|
|
file.</para></listitem><listitem><para>You define exceptions to those
|
|
default policies in the <ulink url="Documentation.htm#Rules"><filename
|
|
class="directory">/etc/shorewall/</filename><filename>rules</filename></ulink>
|
|
file.</para></listitem></itemizedlist>For each connection request entering
|
|
the firewall, the request is first checked against the <filename
|
|
class="directory">/etc/shorewall/</filename><filename>rules</filename>
|
|
file. If no rule in that file matches the connection request then the
|
|
first policy in <filename class="directory">/etc/shorewall/</filename><filename>policy</filename>
|
|
that matches the request is applied. If that policy is <varname>REJECT</varname>
|
|
or <varname>DROP</varname> the request is first checked against the rules
|
|
in <filename class="directory">/etc/shorewall/</filename><filename>common</filename>
|
|
if that file exists; otherwise the rules in <filename class="directory">/etc/shorewall/</filename><filename>common.def</filename>
|
|
are checked.</para>
|
|
|
|
<para>The <filename class="directory">/etc/shorewall/</filename><filename>policy</filename>
|
|
file included with the three-interface sample has the following policies:
|
|
<programlisting>#SOURCE DEST POLICY LOG LEVEL LIMIT:BURST
|
|
loc net ACCEPT
|
|
net all DROP info
|
|
all all REJECT info</programlisting>In the three-interface
|
|
sample, the line below is included but commented out. If you want your
|
|
firewall system to have full access to servers on the internet, uncomment
|
|
that line. <programlisting>#SOURCE DEST POLICY LOG LEVEL LIMIT:BURST
|
|
fw net ACCEPT</programlisting> The above policy will:
|
|
<itemizedlist><listitem><para>Allow all connection requests from your
|
|
local network to the internet</para></listitem><listitem><para>Drop
|
|
(ignore) all connection requests from the internet to your firewall or
|
|
local network</para></listitem><listitem><para>Optionally accept all
|
|
connection requests from the firewall to the internet (if you uncomment
|
|
the additional policy)</para></listitem><listitem><para>reject all other
|
|
connection requests.</para></listitem></itemizedlist></para>
|
|
|
|
<para>The simplest way to define 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>
|
|
</section>
|
|
|
|
<section>
|
|
<title>License</title>
|
|
|
|
<para>This program is free software; you can redistribute it and/or modify
|
|
it under the terms of <ulink url="http://www.gnu.org/licenses/gpl.html">Version
|
|
2 of the GNU General Public License</ulink> as published by the Free
|
|
Software Foundation.</para>
|
|
|
|
<para>This program is distributed in the hope that it will be useful, but
|
|
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
|
|
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
|
|
for more detail.</para>
|
|
|
|
<para>You should have received a copy of the GNU General Public License
|
|
along with this program; if not, write to the Free Software Foundation,
|
|
Inc., 675 Mass Ave, Cambridge, MA 02139, USA</para>
|
|
</section>
|
|
</article> |