source: postlfs/security/iptables.xml@ 8008a55

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
  <!ENTITY % general-entities SYSTEM "../../general.ent">
  %general-entities;

  <!ENTITY iptables-download-http "http://www.netfilter.org/projects/iptables/files/iptables-&iptables-version;.tar.bz2">
  <!ENTITY iptables-download-ftp  "ftp://ftp.netfilter.org/pub/iptables/iptables-&iptables-version;.tar.bz2">
  <!ENTITY iptables-md5sum        "0a9209f928002e5eee9cdff8fef4d4b3">
  <!ENTITY iptables-size          "169 KB">
  <!ENTITY iptables-buildsize     "4.0 MB">
  <!ENTITY iptables-time          "0.1 SBU">
]>

<sect1 id="iptables" xreflabel="iptables-&iptables-version;">
  <?dbhtml filename="iptables.html"?>

  <sect1info>
    <othername>$LastChangedBy$</othername>
    <date>$Date$</date>
  </sect1info>

  <title>Iptables-&iptables-version;</title>

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

  <sect2 role="package">
    <title>Introduction to Iptables</title>

  <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>

    <bridgehead renderas="sect3">Package Information</bridgehead>
    <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>

    <para condition="html" role="usernotes">User Notes:
    <ulink url="&blfs-wiki;/iptables"/></para>

  </sect2>

  <sect2 role="kernel" id='iptables-kernel'>
    <title>Kernel Configuration</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 Networking &rArr;
    Networking Options &rArr; Network Packet Filtering &rArr;
    Core Netfilter Configuration (and) IP: Netfilter Configuration.</para>

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

  </sect2>

    <sect2 role="installation">
      <title>Installation of Iptables</title>

    <note>
      <para>The installation below does not include building some specialized
      extension libraries which require the raw headers in the
      <application>Linux</application> source code. If you wish to build the
      additional extensions (if you aren't sure, then you probably don't), you
      can look at the <filename>INSTALL</filename> file to see an example of
      how to change the <parameter>KERNEL_DIR=</parameter> parameter to point
      at the <application>Linux</application> source code. Note that if you
      upgrade the kernel version, you may also need to recompile
      <application>iptables</application> and that the BLFS team has not tested
      using the raw kernel headers.</para>

      <!-- <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
      from the <application>Linux-Libc-Headers</application> package during
      the base LFS installation.</para> -->
  
      <para>For some non-x86 architectures, the raw kernel headers may be
      required. In that case, modify the <parameter>KERNEL_DIR=</parameter>
      parameter to point at the <application>Linux</application> source
      code.</para>
    </note>

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

<screen><userinput>sed -i 's/name="$node/name="node/' iptables.xslt &amp;&amp;
make LIBDIR=/lib KERNEL_DIR=/usr</userinput></screen>

    <para>This package does not come with a test suite.</para>

    <para>Now, as the <systemitem class="username">root</systemitem> user:</para>

<screen role="root"><userinput>make PREFIX=/usr LIBDIR=/lib BINDIR=/sbin \
    MANDIR=/usr/share/man install &amp;&amp;
install -v -m644 iptables.xslt /lib/iptables</userinput></screen>

  </sect2>

  <sect2 role="commands">
    <title>Command Explanations</title>

    <para><command>sed -i 's/name="$node/name="node/' iptables.xslt</command>:
    This corrects a syntax error in the XSLT stylesheet for use with
    <command>iptables-xml</command>.</para>

    <para><parameter>PREFIX=/usr LIBDIR=/lib BINDIR=/sbin</parameter>:
    Compiles and installs <application>iptables</application> modules
    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>

    <para><parameter>KERNEL_DIR=/usr</parameter>: This parameter is used to
    point at the sanitized kernel headers in
    <filename class='directory'>/usr</filename> and not use the raw kernel
    headers in <filename class='directory'>/usr/src/linux</filename>.</para>

  </sect2>

  <sect2 role="configuration">
    <title>Configuring Iptables</title>

    <para>Introductory instructions for configuring your firewall are
    presented in the next section: <xref linkend='fw-firewall'/></para>

    <sect3  id="iptables-init">
      <title>Boot Script</title>

      <para>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="bootscripts"/> package.</para>

      <indexterm zone="iptables iptables-init">
        <primary sortas="f-iptables">iptables</primary>
      </indexterm>

<screen role="root"><userinput>make install-iptables</userinput></screen>

    </sect3>

  </sect2>

  <sect2 role="content">
    <title>Contents</title>

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

      <seglistitem>
        <seg>iptables, iptables-restore, iptables-save, iptables-xml 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"?>
      <?dbhtml list-presentation="table"?>

      <varlistentry id="iptables-prog">
        <term><command>iptables</command></term>
        <listitem>
          <para>is used to set up, maintain, and inspect the tables of
          IP 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 IP Tables from data
          specified on STDIN. 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 IP Table
          in easily parseable format to STDOUT. 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="iptables-xml">
        <term><command>iptables-xml</command></term>
        <listitem>
          <para>is used to convert the output of
          <command>iptables-save</command> to an XML format. Using the
          <filename>iptables.xslt</filename> stylesheet converts the XML
          bask to the format of <command>iptables-restore</command>.</para>
          <indexterm zone="iptables iptables-xml">
            <primary sortas="b-iptables-xml">iptables-xml</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
          IPv6 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>