svn commit: r44132 - head/en_US.ISO8859-1/books/handbook/advanced-networking
Dru Lavigne
dru at FreeBSD.org
Wed Mar 5 17:26:02 UTC 2014
Author: dru
Date: Wed Mar 5 17:26:02 2014
New Revision: 44132
URL: http://svnweb.freebsd.org/changeset/doc/44132
Log:
Clarify introduction.
Sponsored by: iXsystems
Modified:
head/en_US.ISO8859-1/books/handbook/advanced-networking/chapter.xml
Modified: head/en_US.ISO8859-1/books/handbook/advanced-networking/chapter.xml
==============================================================================
--- head/en_US.ISO8859-1/books/handbook/advanced-networking/chapter.xml Wed Mar 5 16:29:37 2014 (r44131)
+++ head/en_US.ISO8859-1/books/handbook/advanced-networking/chapter.xml Wed Mar 5 17:26:02 2014 (r44132)
@@ -3855,146 +3855,62 @@ ifconfig_<literal>lagg0</literal>="laggp
<primary>diskless operation</primary>
</indexterm>
- <para>A &os; machine can boot over the network and operate
- without a local disk, using file systems mounted from an
- <acronym>NFS</acronym> server. No system modification is
- necessary, beyond standard configuration files. Such a system
- is relatively easy to set up because all the necessary elements
- are readily available:</para>
-
- <itemizedlist>
- <listitem>
<para>The &intel; Preboot eXecution Environment
- (<acronym>PXE</acronym>) can be used to load the kernel over
- the network. It provides a form of smart boot
- <acronym>ROM</acronym> built into some networking cards or
- motherboards. See &man.pxeboot.8; for more details.</para>
- </listitem>
-
- <listitem>
- <para>A sample script
- (<filename>/usr/share/examples/diskless/clone_root</filename>)
- eases the creation and maintenance of the workstation's root
- file system on the server. The script will probably require
- a little customization.</para>
- </listitem>
-
- <listitem>
- <para>Standard system startup files exist in
- <filename>/etc</filename> to detect and support a diskless
- system startup.</para>
- </listitem>
-
- <listitem>
- <para>Swapping, if needed, can be done either to an
- <acronym>NFS</acronym> file or to a local disk.</para>
- </listitem>
-</itemizedlist>
-
- <para>To use <acronym>PXE</acronym> when the machine starts,
- select the <literal>Boot from network</literal> option in
- the <acronym>BIOS</acronym> setup or type a function key
- during system initialization.</para>
-
- <para>There are many ways to set up diskless workstations. Many
- elements are involved, and most can be customized to suit local
- taste. The following will describe variations on the setup of a
- complete system, emphasizing simplicity and compatibility with
- the standard &os; startup scripts. The system described has
- the following characteristics:</para>
-
- <itemizedlist>
- <listitem>
- <para>The diskless workstations use a shared, read-only
- <filename>/</filename> and
- <filename>/usr</filename>.</para>
- </listitem>
-
- <listitem>
- <para>The root file system is a copy of a standard &os; root,
- with some configuration files overridden by ones specific to
- diskless operation or, possibly, to the workstation they
- belong to.</para>
- </listitem>
-
- <listitem>
- <para>The parts of the root which have to be writable are
- overlaid with &man.md.4; file systems. Any changes will be
- lost when the system reboots.</para>
- </listitem>
- </itemizedlist>
-
- <caution>
- <para>As described, this system is insecure. It should live in
- a protected area of a network and be untrusted by other
- hosts.</para>
- </caution>
-
- <sect2>
- <title>Background Information</title>
+ (<acronym>PXE</acronym>) allows an operating system to boot
+ over the network. For example, a &os; system can boot over the network and operate
+ without a local disk, using file systems mounted from an
+ <acronym>NFS</acronym> server. <acronym>PXE</acronym> support is usually
+ available in the <acronym>BIOS</acronym>. To use
+ <acronym>PXE</acronym> when the machine starts,
+ select the <literal>Boot from network</literal> option in
+ the <acronym>BIOS</acronym> setup or type a function key
+ during system initialization.</para>
- <para>When setting up diskless workstations, several operations
- need to be performed for a successful
- bootstrap:</para>
+ <para>In order to provide the files needed for an operating system
+ to boot over the network, a
+ <acronym>PXE</acronym> setup also requires properly configured
+ <acronym>DHCP</acronym>, <acronym>TFTP</acronym>, and <acronym>NFS</acronym>
+ servers, where:</para>
<itemizedlist>
<listitem>
- <para>The machine needs to obtain initial parameters such as
- its <acronym>IP</acronym> address, executable filename,
- server name, and root path. This is done using the
- <acronym>DHCP</acronym> or <acronym>BOOTP</acronym>
- protocols. <acronym>DHCP</acronym> is a compatible
- extension of <acronym>BOOTP</acronym>, and uses the same
- port numbers and basic packet format. It is possible to
- configure a system to use only <acronym>BOOTP</acronym>
- and &man.bootpd.8; is included in the base &os;
- system.</para>
-
- <para><acronym>DHCP</acronym> has a number of advantages
- over <acronym>BOOTP</acronym> such as nicer configuration
- files and support for <acronym>PXE</acronym>. This
- section describes mainly a <acronym>DHCP</acronym>
- configuration, with equivalent examples using
- &man.bootpd.8; when possible. The sample configuration
- uses <application>ISC DHCP</application> which is
- available in the Ports Collection.</para>
- </listitem>
+ <para>Initial parameters, such as an
+ <acronym>IP</acronym> address, executable boot filename and location,
+ server name, and root path are obtained from the
+ <acronym>DHCP</acronym> server.</para>
+ </listitem>
<listitem>
- <para>The machine needs to boot the loader using
+ <para>The operating system loader file is booted using
<acronym>TFTP</acronym>.</para>
</listitem>
<listitem>
- <para>The root filesystem needs to be loaded using
+ <para>The file systems are loaded using
<acronym>NFS</acronym>.</para>
</listitem>
-
- <listitem>
- <para>The possible intermediate bootstrap programs and the
- kernel need to be initialized and executed.
- <acronym>PXE</acronym> loads &man.pxeboot.8;, which is
- a modified version of the &os; third stage loader,
- &man.loader.8;. The third stage loader will obtain most
- parameters necessary to system startup and leave them
- in the kernel environment before transferring control.
- It is possible to use a <filename>GENERIC</filename>
- kernel in this case.</para>
- </listitem>
-
- <listitem>
- <para>Finally, the machine needs to access its file systems
- using <acronym>NFS</acronym>.</para>
- </listitem>
</itemizedlist>
- <para>Place <filename>tftpboot</filename>
- anywhere on the server. Make sure that the location is
- set in both <filename>/etc/inetd.conf</filename> and
- <filename>/usr/local/etc/dhcpd.conf</filename>.</para>
+ <para>When a computer <acronym>PXE</acronym> boots, it receives information over
+ <acronym>DHCP</acronym> about where to obtain the initial boot
+ loader file. After the host computer
+ receives this information, it downloads the boot loader via
+ <acronym>TFTP</acronym> and then executes the boot loader.
+ In &os;, the boot loader file is
+ <filename>/boot/pxeboot</filename>. After
+ <filename>/boot/pxeboot</filename> executes, the &os; kernel is
+ loaded and the rest of the &os; bootup sequence proceeds, as described in
+ <xref linkend="boot"/>.</para>
- <para>Refer to &man.diskless.8; for more information.</para>
- </sect2>
+ <para>This section describes how to configure these services
+ on a &os; system so that other systems can
+ <acronym>PXE</acronym> boot into &os;. Refer to &man.diskless.8; for more information.</para>
+
+ <caution>
+ <para>As described, the system providing these services is insecure. It should live in
+ a protected area of a network and be untrusted by other
+ hosts.</para>
+ </caution>
<sect2 xml:id="network-pxe-nfs">
<info>
@@ -4015,32 +3931,6 @@ ifconfig_<literal>lagg0</literal>="laggp
</authorgroup>
</info>
- <para>The &intel; Preboot eXecution Environment
- (<acronym>PXE</acronym>) allows booting the operating system
- over the network. <acronym>PXE</acronym> support is usually
- provided in the <acronym>BIOS</acronym> where it can be enabled
- in the <acronym>BIOS</acronym> settings which enable booting
- from the network. A fully functioning
- <acronym>PXE</acronym> setup also requires properly configured
- <acronym>DHCP</acronym> and <acronym>TFTP</acronym>
- servers.</para>
-
- <para>When the host computer boots, it receives information over
- <acronym>DHCP</acronym> about where to obtain the initial boot
- loader via <acronym>TFTP</acronym>. After the host computer
- receives this information, it downloads the boot loader via
- <acronym>TFTP</acronym> and then executes the boot loader.
- This is documented in section 2.2.1 of the <link
- xlink:href="http://download.intel.com/design/archives/wfm/downloads/pxespec.pdf">Preboot
- Execution Environment (<acronym>PXE</acronym>)
- Specification</link>. In &os;, the boot loader retrieved
- during the <acronym>PXE</acronym> process is
- <filename>/boot/pxeboot</filename>. After
- <filename>/boot/pxeboot</filename> executes, the &os; kernel is
- loaded and the rest of the &os; bootup sequence proceeds.
- Refer to <xref linkend="boot"/> for more information about the
- &os; booting process.</para>
-
<procedure>
<step>
<para>Choose a directory which will have a &os;
@@ -4051,6 +3941,11 @@ ifconfig_<literal>lagg0</literal>="laggp
<screen>&prompt.root; <userinput>export NFSROOTDIR=/b/tftpboot/FreeBSD/install</userinput>
&prompt.root; <userinput>mkdir -p ${NFSROOTDIR}</userinput></screen>
+
+ <para>Place <filename>tftpboot</filename>
+ anywhere on the server. Make sure that the location is
+ set in both <filename>/etc/inetd.conf</filename> and
+ <filename>/usr/local/etc/dhcpd.conf</filename>.</para>
</step>
<step>
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