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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta name="generator" content="HTML Tidy, see www.w3.org" /><title>Network File System (NFS)</title><meta name="GENERATOR" content="Modular DocBook HTML Stylesheet Version 1.7" /><link rel="HOME" title="FreeBSD Handbook" href="index.html" /><link rel="UP" title="Network Servers" href="network-servers.html" /><link rel="PREVIOUS" title="The inetd Super-Server" href="network-inetd.html" /><link rel="NEXT" title="Network Information System (NIS/YP)" href="network-nis.html" /><link rel="STYLESHEET" type="text/css" href="docbook.css" /></head><body class="SECT1" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#840084"alink="#0000FF"><div class="NAVHEADER"><table summary="Header navigation table" width="100%" border="0" cellpadding="0"cellspacing="0"><tr><th colspan="3" align="center">FreeBSD Handbook</th></tr><tr><td width="10%" align="left" valign="bottom"><a href="network-inetd.html"accesskey="P">Prev</a></td><td width="80%" align="center" valign="bottom">Chapter 23 Network Servers</td><td width="10%" align="right" valign="bottom"><a href="network-nis.html"accesskey="N">Next</a></td></tr></table><hr align="LEFT" width="100%" /></div><div class="SECT1"><h1 class="SECT1"><a id="NETWORK-NFS" name="NETWORK-NFS">23.3 Network File System(NFS)</a></h1><i class="AUTHORGROUP"><span class="CONTRIB">Reorganized and enhanced by</span> TomRhodes.</i> <i class="AUTHORGROUP"><span class="CONTRIB">Written by</span> BillSwingle.</i> <p>Among the many different filesystems that FreeBSD supports is the Network File System,also known as <acronym title="Network File System" class="ACRONYM">NFS</acronym>.<acronym title="Network File System" class="ACRONYM">NFS</acronym> allows a system toshare directories and files with others over a network. By using <acronymtitle="Network File System" class="ACRONYM">NFS</acronym>, users and programs can accessfiles on remote systems almost as if they were local files.</p><p>Some of the most notable benefits that <acronym class="ACRONYM">NFS</acronym> canprovide are:</p><ul><li><p>Local workstations use less disk space because commonly used data can be stored on asingle machine and still remain accessible to others over the network.</p></li><li><p>There is no need for users to have separate home directories on every network machine.Home directories could be set up on the <acronym class="ACRONYM">NFS</acronym> server andmade available throughout the network.</p></li><li><p>Storage devices such as floppy disks, CDROM drives, and <spanclass="TRADEMARK">Zip</span>® drives can be used by other machines on the network.This may reduce the number of removable media drives throughout the network.</p></li></ul><div class="SECT2"><h2 class="SECT2"><a id="AEN33453" name="AEN33453">23.3.1 How <acronymclass="ACRONYM">NFS</acronym> Works</a></h2><p><acronym class="ACRONYM">NFS</acronym> consists of at least two main parts: a serverand one or more clients. The client remotely accesses the data that is stored on theserver machine. In order for this to function properly a few processes have to beconfigured and running.</p><div class="NOTE"><blockquote class="NOTE"><p><b>Note:</b> In FreeBSD 5.X, the <b class="APPLICATION">portmap</b> utility has beenreplaced with the <b class="APPLICATION">rpcbind</b> utility. Thus, in FreeBSD 5.X theuser is required to replace every instance of <b class="APPLICATION">portmap</b> with <bclass="APPLICATION">rpcbind</b> in the forthcoming examples.</p></blockquote></div><p>The server has to be running the following daemons:</p><div class="INFORMALTABLE"><a id="AEN33480" name="AEN33480"></a><table border="0" frame="void" width="100%" class="CALSTABLE"><col width="25%" /><col width="75%" /><thead><tr><th>Daemon</th><th>Description</th></tr></thead><tbody><tr><td><b class="APPLICATION">nfsd</b></td><td>The <acronym class="ACRONYM">NFS</acronym> daemon which services requests from the<acronym class="ACRONYM">NFS</acronym> clients.</td></tr><tr><td><b class="APPLICATION">mountd</b></td><td>The <acronym class="ACRONYM">NFS</acronym> mount daemon which carries out therequests that <a href="http://www.FreeBSD.org/cgi/man.cgi?query=nfsd&sektion=8"><spanclass="CITEREFENTRY"><span class="REFENTRYTITLE">nfsd</span>(8)</span></a> passes on toit.</td></tr><tr><td><b class="APPLICATION">portmap</b></td><td>The portmapper daemon allows <acronym class="ACRONYM">NFS</acronym> clients todiscover which port the <acronym class="ACRONYM">NFS</acronym> server is using.</td></tr></tbody></table></div><p>The client can also run a daemon, known as <b class="APPLICATION">nfsiod</b>. The <bclass="APPLICATION">nfsiod</b> daemon services the requests from the <acronymclass="ACRONYM">NFS</acronym> server. This is optional, and improves performance, but isnot required for normal and correct operation. See the <ahref="http://www.FreeBSD.org/cgi/man.cgi?query=nfsiod&sektion=8"><spanclass="CITEREFENTRY"><span class="REFENTRYTITLE">nfsiod</span>(8)</span></a> manual pagefor more information.</p></div><div class="SECT2"><h2 class="SECT2"><a id="NETWORK-CONFIGURING-NFS" name="NETWORK-CONFIGURING-NFS">23.3.2Configuring <acronym class="ACRONYM">NFS</acronym></a></h2><p><acronym class="ACRONYM">NFS</acronym> configuration is a relatively straightforwardprocess. The processes that need to be running can all start at boot time with a fewmodifications to your <tt class="FILENAME">/etc/rc.conf</tt> file.</p><p>On the <acronym class="ACRONYM">NFS</acronym> server, make sure that the followingoptions are configured in the <tt class="FILENAME">/etc/rc.conf</tt> file:</p><pre class="PROGRAMLISTING">portmap_enable="YES"nfs_server_enable="YES"mountd_flags="-r"</pre><p><b class="APPLICATION">mountd</b> runs automatically whenever the <acronymclass="ACRONYM">NFS</acronym> server is enabled.</p><p>On the client, make sure this option is present in <ttclass="FILENAME">/etc/rc.conf</tt>:</p><pre class="PROGRAMLISTING">nfs_client_enable="YES"</pre><p>The <tt class="FILENAME">/etc/exports</tt> file specifies which filesystems <acronymclass="ACRONYM">NFS</acronym> should export (sometimes referred to as ``share''). Eachline in <tt class="FILENAME">/etc/exports</tt> specifies a filesystem to be exported andwhich machines have access to that filesystem. Along with what machines have access tothat filesystem, access options may also be specified. There are many such options thatcan be used in this file but only a few will be mentioned here. You can easily discoverother options by reading over the <ahref="http://www.FreeBSD.org/cgi/man.cgi?query=exports&sektion=5"><spanclass="CITEREFENTRY"><span class="REFENTRYTITLE">exports</span>(5)</span></a> manualpage.</p><p>Here are a few example <tt class="FILENAME">/etc/exports</tt> entries:</p><p>The following examples give an idea of how to export filesystems, although thesettings may be different depending on your environment and network configuration. Forinstance, to export the <tt class="FILENAME">/cdrom</tt> directory to three examplemachines that have the same domain name as the server (hence the lack of a domain namefor each) or have entries in your <tt class="FILENAME">/etc/hosts</tt> file. The <varclass="OPTION">-ro</var> flag makes the exported filesystem read-only. With this flag,the remote system will not be able to write any changes to the exported filesystem.</p><pre class="PROGRAMLISTING">/cdrom -ro host1 host2 host3</pre><p>The following line exports <tt class="FILENAME">/home</tt> to three hosts by IPaddress. This is a useful setup if you have a private network without a <acronymclass="ACRONYM">DNS</acronym> server configured. Optionally the <ttclass="FILENAME">/etc/hosts</tt> file could be configured for internal hostnames; pleasereview <a href="http://www.FreeBSD.org/cgi/man.cgi?query=hosts&sektion=5"><spanclass="CITEREFENTRY"><span class="REFENTRYTITLE">hosts</span>(5)</span></a> for moreinformation. The <var class="OPTION">-alldirs</var> flag allows the subdirectories to bemount points. In other words, it will not mount the subdirectories but permit the clientto mount only the directories that are required or needed.</p><pre class="PROGRAMLISTING">/home -alldirs 10.0.0.2 10.0.0.3 10.0.0.4</pre><p>The following line exports <tt class="FILENAME">/a</tt> so that two clients fromdifferent domains may access the filesystem. The <var class="OPTION">-maproot=root</var>flag allows the <tt class="USERNAME">root</tt> user on the remote system to write data onthe exported filesystem as <tt class="USERNAME">root</tt>. If the <varclass="LITERAL">-maproot=root</var> flag is not specified, then even if a user has <ttclass="USERNAME">root</tt> access on the remote system, he will not be able to modifyfiles on the exported filesystem.</p><pre class="PROGRAMLISTING">/a -maproot=root host.example.com box.example.org</pre><p>In order for a client to access an exported filesystem, the client must havepermission to do so. Make sure the client is listed in your <ttclass="FILENAME">/etc/exports</tt> file.</p><p>In <tt class="FILENAME">/etc/exports</tt>, each line represents the export informationfor one filesystem to one host. A remote host can only be specified once per filesystem,and may only have one default entry. For example, assume that <ttclass="FILENAME">/usr</tt> is a single filesystem. The following <ttclass="FILENAME">/etc/exports</tt> would be invalid:</p><pre class="PROGRAMLISTING">/usr/src client/usr/ports client</pre><p>One filesystem, <tt class="FILENAME">/usr</tt>, has two lines specifying exports tothe same host, <tt class="HOSTID">client</tt>. The correct format for this situationis:</p><pre class="PROGRAMLISTING">/usr/src /usr/ports client</pre><p>The properties of one filesystem exported to a given host must all occur on one line.Lines without a client specified are treated as a single host. This limits how you canexport filesystems, but for most people this is not an issue.</p><p>The following is an example of a valid export list, where <ttclass="FILENAME">/usr</tt> and <tt class="FILENAME">/exports</tt> are localfilesystems:</p><pre class="PROGRAMLISTING"># Export src and ports to client01 and client02, but only# client01 has root privileges on it/usr/src /usr/ports -maproot=root client01/usr/src /usr/ports client02# The client machines have root and can mount anywhere# on /exports. Anyone in the world can mount /exports/obj read-only/exports -alldirs -maproot=root client01 client02/exports/obj -ro</pre><p>You must restart <b class="APPLICATION">mountd</b> whenever you modify <ttclass="FILENAME">/etc/exports</tt> so the changes can take effect. This can beaccomplished by sending the HUP signal to the <tt class="COMMAND">mountd</tt>process:</p><pre class="SCREEN"><samp class="PROMPT">#</samp> <kbdclass="USERINPUT">kill -HUP `cat /var/run/mountd.pid`</kbd></pre><p>Alternatively, a reboot will make FreeBSD set everything up properly. A reboot is notnecessary though. Executing the following commands as <tt class="USERNAME">root</tt>should start everything up.</p><p>On the <acronym class="ACRONYM">NFS</acronym> server:</p><pre class="SCREEN"><samp class="PROMPT">#</samp> <kbd class="USERINPUT">portmap</kbd><samp class="PROMPT">#</samp> <kbd class="USERINPUT">nfsd -u -t -n 4</kbd><samp class="PROMPT">#</samp> <kbd class="USERINPUT">mountd -r</kbd></pre>⌨️ 快捷键说明
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