glfs/postlfs/security/iptables.xml

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
   "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
  <!ENTITY % general-entities SYSTEM "../../general.ent">
  %general-entities;

  <!ENTITY iptables-download-http "http://www.iptables.org/files/iptables-&iptables-version;.tar.bz2">
  <!ENTITY iptables-download-ftp  "ftp://ftp.netfilter.org/pub/iptables/iptables-&iptables-version;.tar.bz2">
  <!ENTITY iptables-md5sum        "c3358a3bd0d7755df0b64a5063db296b">
  <!ENTITY iptables-size          "177 KB">
  <!ENTITY iptables-buildsize     "3.8 MB">
  <!ENTITY iptables-time          "0.14 SBU">
]>

<sect1 id="iptables" xreflabel="iptables-&iptables-version;">
<sect1info>
<othername>$LastChangedBy$</othername>
<date>$Date$</date>
</sect1info>
<?dbhtml filename="iptables.html"?>
<title>iptables-&iptables-version;</title>

<indexterm zone="iptables">
  <primary sortas="a-Iptables">Iptables</primary>
</indexterm>

<para>The next part of this chapter deals with firewalls.  The principal
firewall tool for Linux, as of the 2.4 kernel series, is
<application>iptables</application>.  It replaces
<application>ipchains</application> from the 2.2 series and
<application>ipfwadm</application> from the 2.0 series. You will need to
install <application>iptables</application> if you intend on using any form of
a firewall.</para>

<sect2 id='iptables-kernel'>
<title>Introduction to <application>iptables</application></title>

<para>A firewall in Linux is accomplished through a portion of the kernel
called netfilter.  The interface to netfilter is <application>iptables</application>.
To use it, the appropriate kernel configuration parameters are found in 
Device Drivers -&gt; Networking Support -&gt; Networking Options -&gt; 
Network Packet Filtering -&gt; IP: Netfilter Configuration.

<indexterm zone="iptables iptables-kernel"> 
  <primary sortas="d-iptables">Iptables</primary>
</indexterm>

</para>

<sect3>
<title>Package information</title>
<itemizedlist spacing='compact'>
  <listitem><para>Download (HTTP): <ulink url="&iptables-download-http;"/></para></listitem>
  <listitem><para>Download (FTP): <ulink url="&iptables-download-ftp;"/></para></listitem>
  <listitem><para>Download MD5 sum: &iptables-md5sum;</para></listitem>
  <listitem><para>Download size: &iptables-size;</para></listitem>
  <listitem><para>Estimated disk space required: &iptables-buildsize;</para></listitem>
  <listitem><para>Estimated build time: &iptables-time;</para></listitem>
</itemizedlist>
</sect3>

</sect2>

<sect2>
<title>Installation of <application>iptables</application></title>

<note>
  <para>Installation of <application>iptables</application> will fail if raw
  kernel headers are found in <filename class='directory'>/usr/src/linux</filename> 
  either as actual files or a symlink.  As of the Linux 2.6 kernel series, 
  this directory should no longer exist because appropriate headers were installed 
  in the linux-libc-headers package during the base <acronym>LFS</acronym> installation.  
  </para>

  <para>For some non-x86 architectures, the raw kernel headers may be required.
  In that case, add the environment variable KERNEL_DIR=/usr/src/linux to the
  make commands below.</para>
</note>

<para>Install <application>iptables</application> by running the following 
commands:</para>

<screen><userinput><command>make PREFIX=/usr LIBDIR=/lib BINDIR=/sbin</command></userinput></screen>

<para>Now, as the root user:</para>

<screen><userinput role='root'><command>make PREFIX=/usr LIBDIR=/lib BINDIR=/sbin install</command></userinput></screen>

</sect2>

<sect2>
<title>Command explanations</title>

<para><parameter>PREFIX=/usr LIBDIR=/lib BINDIR=/sbin</parameter>: Compiles 
and installs <application>iptables</application> libraries into 
<filename class="directory">/lib</filename>, binaries into 
<filename class="directory">/sbin</filename> and the remainder into the 
<filename class="directory">/usr</filename> hierarchy instead of 
<filename class="directory">/usr/local</filename>. Firewalls are
generally activated during the boot process and 
<filename class="directory">/usr</filename> may not be mounted at that 
time.</para>

</sect2>

<sect2>
<title>Installing the iptables bootscript</title>

<para id="iptables-init">To set up the iptables firewall at boot, install the
<filename>/etc/rc.d/init.d/iptables</filename> init script included in the
<xref linkend="intro-important-bootscripts"/> package.</para>

<indexterm zone="iptables iptables-init">
  <primary sortas="f-iptables">iptables</primary>
</indexterm>
 
<screen><userinput role='root'><command>make install-iptables</command></userinput></screen>
  
<para>Introductory instructions for configuring your firewall are presented
in the next section: <xref linkend='fw-firewall'/> </para> 

</sect2>


<sect2>
<title>Contents</title>

<segmentedlist>
<segtitle>Installed Programs</segtitle>
<segtitle>Installed Libraries</segtitle>
<segtitle>Installed Directory</segtitle>

<seglistitem>
<seg>iptables, iptables-restore, iptables-save and ip6tables</seg>
<seg>libip6t_*.so and libipt_*.so</seg>
<seg>/lib/iptables</seg>
</seglistitem>
</segmentedlist>

<variablelist>
<bridgehead renderas="sect3">Short Descriptions</bridgehead>
<?dbfo list-presentation="list"?>

<varlistentry id="iptables-prog">
  <term><command>iptables</command></term>
  <listitem><para>is used to set up, maintain, and inspect the tables of 
    <acronym>IP</acronym> packet filter rules in the Linux kernel.</para>
    <indexterm zone="iptables iptables-prog">
      <primary sortas="b-iptables">iptables</primary>
    </indexterm>
  </listitem>
</varlistentry>

<varlistentry id="iptables-restore">
  <term><command>iptables-restore</command></term>
  <listitem><para>is used to restore <acronym>IP</acronym> Tables from data 
    specified on <acronym>STDIN</acronym>. Use I/O redirection provided by your 
    shell to read from a file.</para>
    <indexterm zone="iptables iptables-restore">
      <primary sortas="b-iptables-restore">iptables-restore</primary>
    </indexterm>
  </listitem>
</varlistentry>

<varlistentry id="iptables-save">
  <term><command>iptables-save</command></term>
  <listitem><para>is used to dump the contents of an <acronym>IP</acronym> Table 
    in easily parseable format to <acronym>STDOUT</acronym>. Use I/O-redirection 
    provided by your shell to write to a file.</para>
    <indexterm zone="iptables iptables-save">
      <primary sortas="b-iptables-save">iptables-save</primary>
    </indexterm>
  </listitem>
</varlistentry>

<varlistentry id="ip6tables">
  <term><command>ip6tables</command></term>
  <listitem><para>is used to set up, maintain, and inspect the tables of 
    <acronym>IP</acronym>v6 packet filter rules in the Linux kernel. Several 
    different tables may be defined. Each table contains a number of built-in 
    chains and may also contain user-defined chains.</para>
    <indexterm zone="iptables ip6tables">
      <primary sortas="b-ip6tables">ip6tables</primary>
    </indexterm>
  </listitem>
</varlistentry>

<varlistentry id="libip-iptables">
  <term><filename class='libraryfile'>libip*.so</filename></term>
  <listitem><para>library modules are various modules (implemented as dynamic 
    libraries) which extend the core functionality of 
    <command>iptables</command>.</para>
    <indexterm zone="iptables libip-iptables">
      <primary sortas="c-libip-iptables">libip*.so</primary>
    </indexterm>
  </listitem>
</varlistentry>

</variablelist>
</sect2>
</sect1>