source: postlfs/security/stunnel.xml@ 5cb3ea7

<?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 stunnel-download-http "http://www.stunnel.org/download/stunnel/src/stunnel-&stunnel-version;.tar.gz">
  <!ENTITY stunnel-download-ftp  "ftp://ftp.fu-berlin.de/unix/linux/mirrors/gentoo/distfiles/stunnel-&stunnel-version;.tar.gz">
  <!ENTITY stunnel-size          "341 KB">
  <!ENTITY stunnel-buildsize     "2.9 MB">
  <!ENTITY stunnel-time          "0.08 SBU">
]>

<sect1 id="stunnel" xreflabel="Stunnel-&stunnel-version;">
<sect1info>
<othername>$LastChangedBy$</othername>
<date>$Date$</date>
</sect1info>
<?dbhtml filename="stunnel.html"?>
<title>Stunnel-&stunnel-version;</title>

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

<para>The <application>Stunnel</application> package contains a program that 
allows you to encrypt arbitrary <acronym>TCP</acronym> connections inside 
<acronym>SSL</acronym> (Secure Sockets Layer) so you can easily communicate 
with clients over secure channels. <application>Stunnel</application> can be 
used to add <acronym>SSL</acronym> functionality to commonly used Inetd 
daemons like <acronym>POP</acronym>-2, <acronym>POP</acronym>-3, and 
<acronym>IMAP</acronym> servers, to standalone daemons like 
<acronym>NNTP</acronym>, <acronym>SMTP</acronym> and <acronym>HTTP</acronym>, 
and in tunneling <acronym>PPP</acronym> over network sockets without changes 
to the server package source code.</para>

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

<sect3><title><application>Stunnel</application> dependencies</title>
<sect4><title>Required</title>
<para><xref linkend="openssl"/></para>
</sect4>

<sect4><title>Optional</title>
<para><xref linkend="tcpwrappers"/></para>
</sect4>
</sect3>

</sect2>

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

<para>The <command>stunnel</command> daemon will be run in a 
<command>chroot</command> jail by an unprivileged user. Create the new user, 
group and <command>chroot</command> home directory structure using the 
following commands:</para>

<screen><userinput><command>groupadd stunnel &amp;&amp;
useradd -c "Stunnel Daemon" -d /var/lib/stunnel -g stunnel -s /bin/false stunnel &amp;&amp;
install -d -m 700 -o stunnel -g stunnel /var/lib/stunnel/run</command></userinput></screen>

<note><para>A signed <acronym>SSL</acronym> Certificate and a Private Key is 
necessary to run the <command>stunnel</command> daemon. If you own, or have 
already created a signed <acronym>SSL</acronym> Certificate you wish to use, 
copy it to <filename>tools/stunnel.pem</filename> in the source directory 
before starting the build, otherwise you will be prompted to create one. The 
<filename>.pem</filename> file must be formatted as shown below:</para>

<screen>-----BEGIN RSA PRIVATE KEY-----
<replaceable>[many encrypted lines of unencrypted key]</replaceable>
-----END RSA PRIVATE KEY-----
-----BEGIN CERTIFICATE-----
<replaceable>[many encrypted lines of certificate]</replaceable>
-----END CERTIFICATE-----</screen></note>

<para>Install <application>Stunnel</application> by running the following 
commands:</para>

<screen><userinput><command>./configure --prefix=/usr --sysconfdir=/etc &amp;&amp;
make &amp;&amp;
make install</command></userinput></screen>

</sect2>

<sect2>
<title>Command explanations</title>

<para><parameter>--sysconfdir=/etc</parameter>: This parameter forces the 
configuration directory to <filename class='directory'>/etc</filename> instead 
of <filename class='directory'>/usr/etc</filename>.</para>

<para><command>make</command>: This command builds the package and, if you
did not copy an <filename>stunnel.pem</filename> file to the source 
<filename class='directory'>tools/</filename> directory, prompts you for the
necessary information to create one. Ensure you reply to the</para>

<screen><computeroutput>Common Name (FQDN of your server) [localhost]:</computeroutput></screen>

<para>prompt with the name or <acronym>IP</acronym> address you will be using 
to access the service.</para>

</sect2>

<sect2>
<title>Configuring <application>Stunnel</application></title>

<sect3><title>Config files</title>
<para><filename>/etc/stunnel/stunnel.conf</filename></para>
</sect3>

<sect3><title>Configuration Information</title>

<para>Create a basic <filename>/etc/stunnel/stunnel.conf</filename> 
configuration file using the following commands:</para>

<screen><userinput><command>cat &gt;/etc/stunnel/stunnel.conf &lt;&lt; "EOF"</command>
# File: /etc/stunnel/stunnel.conf

pid = /run/stunnel.pid
chroot = /var/lib/stunnel
client = no
setuid = stunnel
setgid = stunnel

<command>EOF</command></userinput></screen>

<para>Next, you need to add the service you wish to encrypt to the 
configuration file. The format is as follows:</para> 

<screen><userinput>[<replaceable>[service]</replaceable>]
accept  = <replaceable>[hostname:portnumber]</replaceable>
connect = <replaceable>[hostname:portnumber]</replaceable></userinput></screen>

<para>If you use <application>Stunnel</application> to encrypt a daemon 
started from <command>[x]inetd</command>, you may need to disable that daemon 
in the <filename>/etc/[x]inetd.conf</filename> file and enable a corresponding 
<replaceable>[service]</replaceable>_stunnel service. You may have to add an 
appropriate entry in <filename>/etc/services</filename> as well.</para>

<para>For a full explanation of the commands and syntax used in the 
configuration file, run <command>man stunnel</command>. To see a 
<acronym>BLFS</acronym> example of an actual setup of an 
<command>stunnel</command> encrypted service, read the 
<acronym>SWAT</acronym> configuration section in the <xref linkend="samba3"/> 
instructions.</para>

<para>To automatically start the <command>stunnel</command> daemon when the system
is rebooted, install the <filename>/etc/rc.d/init.d/stunnel</filename> 
bootscript from the <xref linkend="intro-important-bootscripts"/> 
package.</para>

<screen><userinput><command>make install-stunnel</command></userinput></screen>
</sect3>

</sect2>

<sect2>
<title>Contents</title>

<para>The <application>Stunnel</application> package contains 
<command>stunnel</command> and 
<filename class='libraryfile'>libstunnel</filename>.</para>

</sect2>

<sect2><title>Description</title>

<sect3><title>stunnel</title>
<para><command>stunnel</command> is a program designed to work as an 
<acronym>SSL</acronym> encryption wrapper between remote clients and local 
(<command>[x]inetd</command>-startable) or remote servers.</para></sect3>

</sect2>

</sect1>