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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>The inetd Super-Server</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="Network Servers" href="network-servers.html" /><link rel="NEXT" title="Network File System (NFS)" href="network-nfs.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-servers.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-nfs.html"accesskey="N">Next</a></td></tr></table><hr align="LEFT" width="100%" /></div><div class="SECT1"><h1 class="SECT1"><a id="NETWORK-INETD" name="NETWORK-INETD">23.2 The <bclass="APPLICATION">inetd</b> ``Super-Server''</a></h1><i class="AUTHORGROUP"><span class="CONTRIB">Contributed by</span> Chern Lee.</i> <div class="SECT2"><h2 class="SECT2"><a id="NETWORK-INETD-OVERVIEW" name="NETWORK-INETD-OVERVIEW">23.2.1Overview</a></h2><p><a href="http://www.FreeBSD.org/cgi/man.cgi?query=inetd&sektion=8"><spanclass="CITEREFENTRY"><span class="REFENTRYTITLE">inetd</span>(8)</span></a> is referredto as the ``Internet Super-Server'' because it manages connections for several daemons.Programs that provide network service are commonly known as daemons. <bclass="APPLICATION">inetd</b> serves as a managing server for other daemons. When aconnection is received by <b class="APPLICATION">inetd</b>, it determines which daemonthe connection is destined for, spawns the particular daemon and delegates the socket toit. Running one instance of <b class="APPLICATION">inetd</b> reduces the overall systemload as compared to running each daemon individually in stand-alone mode.</p><p>Primarily, <b class="APPLICATION">inetd</b> is used to spawn other daemons, butseveral trivial protocols are handled directly, such as <bclass="APPLICATION">chargen</b>, <b class="APPLICATION">auth</b>, and <bclass="APPLICATION">daytime</b>.</p><p>This section will cover the basics in configuring <b class="APPLICATION">inetd</b>through its command-line options and its configuration file, <ttclass="FILENAME">/etc/inetd.conf</tt>.</p></div><div class="SECT2"><h2 class="SECT2"><a id="NETWORK-INETD-SETTINGS" name="NETWORK-INETD-SETTINGS">23.2.2Settings</a></h2><p><b class="APPLICATION">inetd</b> is initialized through the <ttclass="FILENAME">/etc/rc.conf</tt> system. The <var class="LITERAL">inetd_enable</var>option is set to <var class="LITERAL">NO</var> by default, but is often times turned onby <b class="APPLICATION">sysinstall</b> with the medium security profile. Placing:</p><pre class="PROGRAMLISTING">inetd_enable="YES"</pre>or <pre class="PROGRAMLISTING">inetd_enable="NO"</pre>into <tt class="FILENAME">/etc/rc.conf</tt> can enable or disable <bclass="APPLICATION">inetd</b> starting at boot time.<br /><br /><p>Additionally, different command-line options can be passed to <bclass="APPLICATION">inetd</b> via the <var class="LITERAL">inetd_flags</var> option.</p></div><div class="SECT2"><h2 class="SECT2"><a id="NETWORK-INETD-CMDLINE" name="NETWORK-INETD-CMDLINE">23.2.3Command-Line Options</a></h2><p><b class="APPLICATION">inetd</b> synopsis:</p><p><var class="OPTION">inetd [-d] [-l] [-w] [-W] [-c maximum] [-C rate] [-a address |hostname] [-p filename] [-R rate] [configuration file]</var></p><div class="VARIABLELIST"><dl><dt>-d</dt><dd><p>Turn on debugging.</p></dd><dt>-l</dt><dd><p>Turn on logging of successful connections.</p></dd><dt>-w</dt><dd><p>Turn on TCP Wrapping for external services (on by default).</p></dd><dt>-W</dt><dd><p>Turn on TCP Wrapping for internal services which are built into <bclass="APPLICATION">inetd</b> (on by default).</p></dd><dt>-c maximum</dt><dd><p>Specify the default maximum number of simultaneous invocations of each service; thedefault is unlimited. May be overridden on a per-service basis with the <varclass="OPTION">max-child</var> parameter.</p></dd><dt>-C rate</dt><dd><p>Specify the default maximum number of times a service can be invoked from a single IPaddress in one minute; the default is unlimited. May be overridden on a per-service basiswith the <var class="OPTION">max-connections-per-ip-per-minute</var> parameter.</p></dd><dt>-R rate</dt><dd><p>Specify the maximum number of times a service can be invoked in one minute; thedefault is 256. A rate of 0 allows an unlimited number of invocations.</p></dd><dt>-a</dt><dd><p>Specify one specific IP address to bind to. Alternatively, a hostname can bespecified, in which case the IPv4 or IPv6 address which corresponds to that hostname isused. Usually a hostname is specified when <b class="APPLICATION">inetd</b> is run insidea <a href="http://www.FreeBSD.org/cgi/man.cgi?query=jail&sektion=8"><spanclass="CITEREFENTRY"><span class="REFENTRYTITLE">jail</span>(8)</span></a>, in which casethe hostname corresponds to the <ahref="http://www.FreeBSD.org/cgi/man.cgi?query=jail&sektion=8"><spanclass="CITEREFENTRY"><span class="REFENTRYTITLE">jail</span>(8)</span></a>environment.</p><p>When hostname specification is used and both IPv4 and IPv6 bindings are desired, oneentry with the appropriate protocol type for each binding is required for each service in<tt class="FILENAME">/etc/inetd.conf</tt>. For example, a TCP-based service would needtwo entries, one using <var class="LITERAL">tcp4</var> for the protocol and the otherusing <var class="LITERAL">tcp6</var>.</p></dd><dt>-p</dt><dd><p>Specify an alternate file in which to store the process ID.</p></dd></dl></div><p>These options can be passed to <b class="APPLICATION">inetd</b> using the <varclass="LITERAL">inetd_flags</var> option in <tt class="FILENAME">/etc/rc.conf</tt>. Bydefault, <var class="LITERAL">inetd_flags</var> is set to <var class="LITERAL">-wW</var>,which turns on TCP wrapping for <b class="APPLICATION">inetd</b>'s internal and externalservices. For novice users, these parameters usually do not need to be modified or evenentered in <tt class="FILENAME">/etc/rc.conf</tt>.</p><div class="NOTE"><blockquote class="NOTE"><p><b>Note:</b> An external service is a daemon outside of <bclass="APPLICATION">inetd</b>, which is invoked when a connection is received for it. Onthe other hand, an internal service is one that <b class="APPLICATION">inetd</b> has thefacility of offering within itself.</p></blockquote></div></div><div class="SECT2"><h2 class="SECT2"><a id="NETWORK-INETD-CONF" name="NETWORK-INETD-CONF">23.2.4 <ttclass="FILENAME">inetd.conf</tt></a></h2><p>Configuration of <b class="APPLICATION">inetd</b> is controlled through the <ttclass="FILENAME">/etc/inetd.conf</tt> file.</p><p>When a modification is made to <tt class="FILENAME">/etc/inetd.conf</tt>, <bclass="APPLICATION">inetd</b> can be forced to re-read its configuration file by sendinga HangUP signal to the <b class="APPLICATION">inetd</b> process as shown:</p><div class="EXAMPLE"><a id="NETWORK-INETD-HANGUP" name="NETWORK-INETD-HANGUP"></a><p><b>Example 23-1. Sending inetd a HangUP Signal</b></p><pre class="SCREEN"><samp class="PROMPT">#</samp> <kbdclass="USERINPUT">kill -HUP `cat /var/run/inetd.pid`</kbd></pre></div><p>Each line of the configuration file specifies an individual daemon. Comments in thefile are preceded by a ``#''. The format of <tt class="FILENAME">/etc/inetd.conf</tt> isas follows:</p><pre class="PROGRAMLISTING">service-namesocket-typeprotocol{wait|nowait}[/max-child[/max-connections-per-ip-per-minute]]user[:group][/login-class]server-programserver-program-arguments</pre><p>An example entry for the <b class="APPLICATION">ftpd</b> daemon using IPv4:</p><pre class="PROGRAMLISTING">⌨️ 快捷键说明
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