source: basicnet/netprogs/tcpwrappers.xml@ b1623c2

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
   "http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd" [
  <!ENTITY % general-entities SYSTEM "../../general.ent">
  %general-entities;

  <!ENTITY tcpwrappers-download-http "http://files.ichilton.co.uk/nfs/tcp_wrappers_&tcpwrappers-version;.tar.gz">
  <!ENTITY tcpwrappers-download-ftp  "ftp://ftp.porcupine.org/pub/security/tcp_wrappers_7.6.tar.gz">
  <!ENTITY tcpwrappers-size          "100 KB">
  <!ENTITY tcpwrappers-buildsize     "720 KB">
  <!ENTITY tcpwrappers-time          "0.16 SBU">
]>

<sect1 id="tcpwrappers" xreflabel="tcpwrappers-&tcpwrappers-version;">
<?dbhtml filename="tcpwrappers.html"?>
<title>tcpwrappers-&tcpwrappers-version;</title>

<sect2>
<title>Introduction to <application>tcpwrappers</application></title>

<para>The <application>tcpwrappers</application> package provides daemon 
wrapper programs that report the name of the client requesting network 
services and the requested service.</para> 

<sect3><title>Package information</title>
<itemizedlist spacing='compact'>
<listitem><para>Download (HTTP): <ulink
url="&tcpwrappers-download-http;"/></para></listitem>
<listitem><para>Download (FTP): <ulink
url="&tcpwrappers-download-ftp;"/></para></listitem>
<listitem><para>Download size: &tcpwrappers-size;</para></listitem>
<listitem><para>Estimated Disk space required:
&tcpwrappers-buildsize;</para></listitem>
<listitem><para>Estimated build time:
&tcpwrappers-time;</para></listitem></itemizedlist>
</sect3>

<sect3><title>Additional downloads</title>
<itemizedlist spacing='compact'>
<listitem><para>Required patch (Fixes some build issues and adds building of a shared library):
<ulink url="&patch-root;/tcp_wrappers-7.6-shared_lib_plus_plus-1.patch"/></para></listitem>
</itemizedlist>
</sect3>

</sect2>

<sect2>
<title>Installation of <application>tcpwrappers</application></title>

<para>Install <application>tcpwrappers</application> with the following 
commands:</para>

<screen><userinput><command>patch -Np1 -i ../tcp_wrappers-7.6-shared_lib_plus_plus-1.patch &amp;&amp;
make REAL_DAEMON_DIR=/usr/sbin STYLE=-DPROCESS_OPTIONS linux &amp;&amp;
make install</command></userinput></screen>

</sect2>

<sect2>
<title>Configuring <application>tcpwrappers</application></title>

<sect3><title>Config files</title>
<para><filename>/etc/hosts.allow</filename>,
<filename>/etc/hosts.deny</filename></para>

<para>File protections: the wrapper, all files used by the wrapper,
and all directories in the path leading to those files, should be
accessible but not writable for unprivileged users (mode 755 or mode
555). Do not install the wrapper set-uid.</para>

<para>Then perform the following edits on the
<filename>/etc/inetd.conf</filename> configuration file:</para>
<screen><userinput>finger stream tcp nowait nobody /usr/sbin/in.fingerd in.fingerd</userinput></screen>
<para>becomes:</para>
<screen><userinput>finger stream tcp nowait nobody /usr/sbin/tcpd in.fingerd</userinput></screen>

<note><para>The finger server is used as an example here.</para></note>

<para>Similar changes must be made if xinetd is used, with the emphasis being 
on calling <command>/usr/sbin/tcpd</command> instead of calling the service 
daemon directly, and passing the name of the service daemon to tcpd.</para>
</sect3>

</sect2>

<sect2>
<title>Contents</title>

<para>The <application>tcpwrappers</application> package contains <command>
tcpd</command>, <command>tcpdchk</command>, <command>tcpdmatch</command>,
<command>try-from</command> and <command>safe_finger</command>.</para>
</sect2>

<sect2><title>Description</title>

<sect3><title>tcpd</title>
<para><command>tcpd</command> is the main access control daemon for all 
Internet services, which <command>inetd</command> or
<command>xinetd</command> will run instead of running the
requested service daemon.</para></sect3>

<sect3><title>tcpdchk</title>
<para><command>tcpdchk</command> is a tool to examine a tcpd wrapper 
configuration and report problems with it.</para></sect3>

<sect3><title>tcpdmatch</title>
<para><command>tcpdmatch</command> is used to predict how the tcp wrapper 
would handle a specific request for a service.</para></sect3>

<sect3><title>try-from</title>
<para><command>try-from</command> can be called via a remote shell command to 
find out if the host name and address are properly recognized.</para></sect3>

<sect3><title>safe_finger</title>
<para><command>safe_finger</command> is a wrapper for the <command>finger
</command> utility, to provide automatic reverse name lookups.</para></sect3>

</sect2>

</sect1>