source: postlfs/security/iptables.xml@ 8bc57f68

<?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        "212112389c7f10c72efb31a4ed193a4c">
  <!ENTITY iptables-size          "482 KB">
  <!ENTITY iptables-buildsize     "15 MB">
  <!ENTITY iptables-time          "0.2 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 is <application>iptables</application>.  You will
  need to install <application>iptables</application> if you intend on using
  any form of a firewall.</para>

  &lfs70_checked;

    <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 Support &rArr;
    Networking Options &rArr; Network Packet Filtering Framework.</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>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 '/if_packet/i#define __aligned_u64 __u64 __attribute__((aligned(8)))' \
   extensions/libxt_pkttype.c &amp;&amp;
./configure --prefix=/usr     \
            --exec-prefix=    \
            --bindir=/sbin    \
            --with-xtlibdir=/lib/xtables \
            --with-pkgconfigdir=/usr/lib/pkgconfig &amp;&amp;
make</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 install &amp;&amp;
ln -sfv xtables-multi /sbin/iptables-xml</userinput></screen>

  </sect2>

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

    <para><command>sed -i '/if_packet/i#define ...</command>: This sed fixes
    compiling <application>iptables</application> with the linux-3.2 kernel
    headers installed. It's not needed if you built LFS with an older
    kernel&apos;s headers, but in that case it does no harm.</para>

    <para><parameter>--exec-prefix=</parameter>: Ensure all binaries and
    libraries end up in <filename class="directory">/</filename> directory
    tree.</para>

    <para><parameter>--bindir=/sbin</parameter>: Ensure all the executables go
    in <filename class="directory">/sbin</filename>.</para>

    <para><parameter>--with-xtlibdir=/lib/xtables</parameter>: Ensure all 
    iptables modules are installed in the 
    <filename class="directory">/lib/xtables</filename> directory.</para>

    <para><parameter>--with-pkgconfigdir=/usr/lib/pkgconfig</parameter>:
    Ensure all the pkgconfig files are in the standard location.</para>

    <para><command>ln -sfv xtables-multi /sbin/iptables-xml</command>: Ensure
    the symbolic link for <command>iptables-xml</command> is relative.</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 Directories</segtitle>

      <seglistitem>
        <seg>iptables, iptables-restore, iptables-save, iptables-xml, 
        ip6tables, ip6tables-restore, ip6tables-save,
        and xtables-multi</seg>
        <seg>libip4tc.so, libip6tc.so, libiptc.so, libxtables.so,
        and numerous modules in /lib/xtables</seg>
        <seg>/lib/xtables, /usr/include/libiptc and /usr/share/xtables</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.  It is a
          symbolic link to xtables-multi.</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. It is a symbolic link to
          xtables-multi.</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. It is a symbolic link to
          xtables-multi.</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
          back to the format of <command>iptables-restore</command>.
          It is a symbolic link to xtables-multi.</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>are a set of commands for IPV6 that parallel the iptables
          commands above.  All of these commands are symbolic
          links to xtables-multi.</para>
          <indexterm zone="iptables ip6tables">
            <primary sortas="b-ip6tables">ip6tables</primary>
          </indexterm>
        </listitem>
      </varlistentry>

    </variablelist>

  </sect2>

</sect1>