Date: Wed, 5 Mar 2014 17:26:02 +0000 (UTC) From: Dru Lavigne <dru@FreeBSD.org> To: doc-committers@freebsd.org, svn-doc-all@freebsd.org, svn-doc-head@freebsd.org Subject: svn commit: r44132 - head/en_US.ISO8859-1/books/handbook/advanced-networking Message-ID: <201403051726.s25HQ2nJ010890@svn.freebsd.org>
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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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