source: postlfs/security/stunnel.xml@ 80d619f0

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   "http://www.oasis-open.org/docbook/xml/4.5/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://stunnel.mirt.net/stunnel/stunnel-&stunnel-version;.tar.gz">
  <!ENTITY stunnel-md5sum        "1eaec5228979beca4d548f453304e311">
  <!ENTITY stunnel-size          "528 KB">
  <!ENTITY stunnel-buildsize     "5 MB">
  <!ENTITY stunnel-time          "0.1 SBU">
]>

<sect1 id="stunnel" xreflabel="Stunnel-&stunnel-version;">
  <?dbhtml filename="stunnel.html"?>

  <sect1info>
    <othername>$LastChangedBy$</othername>
    <date>$Date$</date>
  </sect1info>

  <title>Stunnel-&stunnel-version;</title>

  <indexterm zone="stunnel">
    <primary sortas="a-Stunnel">Stunnel</primary>
  </indexterm>

  <sect2 role="package">
    <title>Introduction to Stunnel</title>

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

    <bridgehead renderas="sect3">Package Information</bridgehead>
    <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 MD5 sum: &stunnel-md5sum;</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>

    <bridgehead renderas="sect3">Additional Downloads</bridgehead>
    <itemizedlist spacing="compact">
      <listitem>
        <para>Required patch: <ulink
        url="&patch-root;/stunnel-&stunnel-version;-setuid-1.patch"/></para>
      </listitem>
    </itemizedlist>

    <bridgehead renderas="sect3">Stunnel Dependencies</bridgehead>

    <bridgehead renderas="sect4">Required</bridgehead>
    <para role="required"><xref linkend="openssl"/></para>

    <bridgehead renderas="sect4">Optional</bridgehead>
    <para role="optional"><xref linkend="tcpwrappers"/></para>

    <para condition="html" role="usernotes">User Notes:
    <ulink url="&blfs-wiki;/stunnel"/></para>

  </sect2>

  <sect2 role="installation">
    <title>Installation of Stunnel</title>

    <para>The <command>stunnel</command> daemon will be run in a
    <command>chroot</command> jail by an unprivileged user. Create the
    new user and group using the following commands as the
    <systemitem class="username">root</systemitem> user:</para>

<screen role="root"><userinput>groupadd -g 51 stunnel &amp;&amp;
useradd -c "Stunnel Daemon" -d /var/lib/stunnel \
        -g stunnel -s /bin/false -u 51 stunnel</userinput></screen>

    <note>
      <para>A signed SSL Certificate and a Private Key is necessary to run
      the <command>stunnel</command> daemon. If you own, or have already
      created a signed SSL Certificate you wish to use, copy it to
      <filename>/etc/stunnel/stunnel.pem</filename> before starting the build
      (ensure only <systemitem class='username'>root</systemitem> has read and
      write access), otherwise you will be
      prompted to create one during the installation process. The
      <filename class='extension'>.pem</filename> file must be formatted as
      shown below:</para>

<screen><literal>-----BEGIN RSA PRIVATE KEY-----
<replaceable>&lt;many encrypted lines of unencrypted key&gt;</replaceable>
-----END RSA PRIVATE KEY-----
-----BEGIN CERTIFICATE-----
<replaceable>&lt;many encrypted lines of certificate&gt;</replaceable>
-----END CERTIFICATE-----</literal></screen>
    </note>

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

<screen><userinput>patch -Np1 -i ../stunnel-&stunnel-version;-setuid-1.patch &amp;&amp;

sed -i 's|nogroup|stunnel|g' configure &amp;&amp;
sed -i 's|$(prefix)/var/lib|$(localstatedir)|' tools/Makefile.in &amp;&amp;

./configure --prefix=/usr \
            --sysconfdir=/etc \
            --localstatedir=/var/lib \
            --disable-libwrap &amp;&amp;
make</userinput></screen>

    <para>This package does not come with a test suite.</para>

    <para>Now, as the <systemitem class="username">root</systemitem> user:</para>

<screen role="root"><userinput>make docdir=/usr/share/doc/stunnel-&stunnel-version; install</userinput></screen>

  </sect2>

  <sect2 role="commands">
    <title>Command Explanations</title>

    <para><command>sed -i 's|nogroup|stunnel|g' configure</command>: This
    command is used to change the default group for the installed files in
    <filename class='directory'>/var/lib/stunnel</filename> from
    <systemitem class="groupname">nogroup</systemitem> to
    <systemitem class="groupname">stunnel</systemitem>.</para>

    <para><command>sed -i '...' tools/Makefile.in</command>: This command
    ensures that the chroot jail will be located in
    <filename class='directory'>/var/lib/stunnel</filename> instead of
    <filename class='directory'>/usr/var/lib/stunnel</filename>.</para>

    <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><parameter>--localstatedir=/var/lib</parameter>: This parameter
    sets the installation to use
    <filename class='directory'>/var/lib/stunnel</filename> instead of
    creating and using
    <filename class='directory'>/usr/var/stunnel</filename>.</para>

    <para><parameter>--disable-libwrap</parameter>: This parameter is required
    if you don't have <application>tcpwrappers</application> installed. Remove
    the parameter if <application>tcpwrappers</application> is installed.</para>

    <para><command>make docdir=... install</command>: This command installs the
    package, changes the documentation installation directory to standard
    naming conventions and, if you did not copy an
    <filename>stunnel.pem</filename> file to the
    <filename class='directory'>/etc/stunnel</filename> directory, prompts you
    for the necessary information to create one. Ensure you reply to the</para>

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

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

  </sect2>

  <sect2 role="configuration">
    <title>Configuring Stunnel</title>

    <sect3 id="stunnel-config">
      <title>Config Files</title>

      <para><filename>/etc/stunnel/stunnel.conf</filename></para>

      <indexterm zone="stunnel stunnel-config">
        <primary sortas="e-etc-stunnel-stunnel.conf">/etc/stunnel/stunnel.conf</primary>
      </indexterm>

    </sect3>

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

      <para>As the <systemitem class="username">root</systemitem> user,
      create the directory used for the
      <filename class='extension'>.pid</filename> file that is created
      when the <application>Stunnel</application> daemon starts:</para>

<screen role="root"><userinput>install -v -m750 -o stunnel -g stunnel -d /var/lib/stunnel/run</userinput></screen>

      <para>Next, create a basic <filename>/etc/stunnel/stunnel.conf</filename>
      configuration file using the following commands as the
      <systemitem class="username">root</systemitem> user:</para>

<screen role="root"><userinput>cat &gt;/etc/stunnel/stunnel.conf &lt;&lt; "EOF" &amp;&amp;
<literal>; File: /etc/stunnel/stunnel.conf

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

EOF
chmod -v 644 /etc/stunnel/stunnel.conf</userinput></screen>

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

<screen><literal>[<replaceable>&lt;service&gt;</replaceable>]
accept  = <replaceable>&lt;hostname:portnumber&gt;</replaceable>
connect = <replaceable>&lt;hostname:portnumber&gt;</replaceable></literal></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>&lt;service&gt;</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
      BLFS example of an actual setup of an <command>stunnel</command> encrypted
      service, read the <xref linkend="samba3-swat-config"/> in the
      <application>Samba</application> instructions.</para>

    </sect3>

    <sect3  id="stunnel-init">
      <title>Boot Script</title>

      <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="bootscripts"/> package.</para>

      <indexterm zone="stunnel stunnel-init">
        <primary sortas="f-stunnel">stunnel</primary>
      </indexterm>

<screen role="root"><userinput>make install-stunnel</userinput></screen>

    </sect3>

  </sect2>

  <sect2 role="content">
    <title>Contents</title>

    <segmentedlist>
      <segtitle>Installed Programs</segtitle>
      <segtitle>Installed Library</segtitle>
      <segtitle>Installed Directories</segtitle>

      <seglistitem>
        <seg>stunnel and stunnel3</seg>
        <seg>libstunnel.so</seg>
        <seg>/etc/stunnel, /usr/lib/stunnel,
        /usr/share/doc/stunnel-&stunnel-version; and
        /var/lib/stunnel</seg>
      </seglistitem>
    </segmentedlist>

    <variablelist>
      <bridgehead renderas="sect3">Short Descriptions</bridgehead>
      <?dbfo list-presentation="list"?>
      <?dbhtml list-presentation="table"?>

      <varlistentry id="stunnel-prog">
        <term><command>stunnel</command></term>
        <listitem>
          <para> is a program designed to work as an SSL
          encryption wrapper between remote clients and local
          (<command>{x}inetd</command>-startable) or remote servers.</para>
          <indexterm zone="stunnel stunnel-prog">
            <primary sortas="b-stunnel">stunnel</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="stunnel3">
        <term><command>stunnel3</command></term>
        <listitem>
          <para>is a <application>Perl</application> wrapper script to use
          <command>stunnel</command> 3.x syntax with <command>stunnel</command>
          >=4.05.</para>
          <indexterm zone="stunnel stunnel3">
            <primary sortas="b-stunnel3">stunnel3</primary>
          </indexterm>
        </listitem>
      </varlistentry>

      <varlistentry id="libstunnel">
        <term><filename class='libraryfile'>libstunnel.so</filename></term>
        <listitem>
          <para> contains the API functions required by
          <application>Stunnel</application>.</para>
          <indexterm zone="stunnel libstunnel">
            <primary sortas="c-libstunnel">libstunnel.so</primary>
          </indexterm>
        </listitem>
      </varlistentry>

    </variablelist>

  </sect2>

</sect1>