<sect1 id="configurations-ppp-server">

    <title>The Server Computer</title>

    <sect2 id="configurations-ppp-server-install">
    <title>Installation</title>

    <para>
        Start with a minimal installation of &TCD;, bootup the
        operating system, and login as root user. Later, install the
        <quote>Dialup Networking Support</quote> group of packages
        available in the <code>[base]</code> repository of &TCD;. The
        installation of this group of packages is required both in
        server and client computers. If you don't have this group of
        packages installed in your computer, then you can do it as the
        following command describes:
    </para>

    <screen>yum groupinstall "Dialup Networking Support"</screen>

    <para>
        Other packages might be required based on whether you are
        configuring the computer to be a server or a client.  The
        implementation described in this chapter considers both a
        server and client configuration so you can pick up the one
        fitting your case.
    </para>

    <sect3 id="configurations-ppp-server-dns">
    <title>Name Server</title>
    <para>
        The name server provides the software required to translate
        domain names into IP address and IP addresses into domain
        names. With this software you can rembember addresses like
        <ulink url="https://projects.centos.org/" /> instead of addresses like
        <ulink url="https://192.168.0.1/" />.  There are other
        feautres (e.g., mail exchanger resolution, zone delegation,
        etc.) provided by this software that aren't used in the
        point-to-point configuration we describe in this chapter.
    </para>
    <para>
        To install this software, run the following command:
    </para>
    <screen>yum install bind</screen>
    <note>
    <para>
        There is a <package>bind-chroot</package> packages, however,
        we aren't using it because SELinux is already enforced on the
        &TCD; filesystem and it provides far more security than the
        idea of <package>bind-chroot</package> package itself does.
    </para>
    </note>
    </sect3>

    <sect3 id="configurations-ppp-server-mail">
    <title>Mail Server</title>
    <para>
        The mail server provides the software required to let you
        send/receive e-mail messages to/from others. The mail server
        is splitted in three basic components: The Mail Transfer Agent
        (<package>postfix</package>), The Mail Delivery Agent
        (<package>Cyrus-Imapd</package>) and an intermediary daemon
        named <systemitem class="daemon">saslauthd</systemitem> to
        handle users' authentication. The mail transfer agent is the
        program your e-mail client sends e-mail messages to. The mail
        delivery agent, on the other hand, is the program your e-mail
        client reads e-mail message from (i.e., this is the place
        where your mailbox is stored in).  The authentication daemon
        is used by the mail delivery agent to authenticate user's
        credentials (e.g., the information that let you access an
        specific mailbox). 
    </para>

    <para>
        To install this software, run the following command:
    </para>

    <screen>yum install postfix cyrus-imapd cyrus-sasl</screen>

    <para>
        By default, the <application>sendmail</application>
        program is used as mail transfer agent, not postfix. For the
        sake of that point-to-point configuration we are implementing,
        I decided to use postfix instead as default mail transfer
        agent, not sendmail.  To effectively achieve this decition, it
        is required to use the <command>alternatives</command>
        command, as it shown below:
    </para>

    <screen>alternatives --config mta</screen>

    <para>
        This command will present you a menu to chose between
        available mail transfer agents, so it is there where you
        choose to use posfix as default option. Now that you've
        changed postfix the default mail transfer agent, you can
        saftly remove the sendmail package to avoid unused software
        to remain inside the computer. To do this, you can run the
        following command:
    </para>

    <screen>yum remove sendmail</screen>

    <para>
       In addition to mail server specific packages, we also provide
       mailing list support. Mailing lists provide e-mail addresses
       that users registered inside the ISP can write to. When you
       sed an e-mail to a mailing list, your message is distributed to
       all members of that list. In order for this to happen, people
       registered inside ISP need to subscribe themselves into that
       mailing list they want to receive messages from.  The
       subscription of mailinglist will be available through a secured
       web application in the following url:
    </para>

    <itemizedlist>
    <listitem>
    <para>
        <ulink url="https://projects.centos.org/lists/" />
    </para>
    </listitem>
    </itemizedlist>
    
    <para>
        To install the mailing list software, run the following
        command:
    </para>

    <screen>yum install mailman</screen>
    </sect3>

    <sect3 id="configurations-ppp-server-web">
    <title>Web Server</title>
    <para>
        The web server provides the software required to support web
        interfaces like those one previously mention to register new
        users inside the ISP and subscribe mailing lists. The web
        server provided in this configuration will accept requests
        both unencrypted and encrypted.
    </para>

    <screen>yum install httpd mod_ssl crypto-utils</screen>

    <para>
        In addition to mailing lists support, the web server will
        provide access to Subversion.  Subvesion provides a way to
        manage files through version control. The main purpose of
        providing Subversion support here is sharing the version of
        &TCAR; I've been working on. To install Subversion software,
        run the following command: </para>

    <screen>yum install subversion mod_dav_svn</screen>

    </sect3>

    <sect3 id="configurations-ppp-server-ldap">
    <title>Directory Server</title>
    <para>
        The directory server provides the software required to unify
        user information. This server is access by other server
        whenever user information is required. You, as end user, can
        also use this server from your workstation to retrive a list
        of all users registered in the ISP. This list can be retrived
        by the web interface the ISP provides, or any application your
        workstation provide (e.g., most e-mail clients provide a way
        to configure LDAP servers to build address book from it.).
    </para>

    <para>
        To install the directory server sofware, run the following
        command:
    </para>

    <screen>yum openldap-servers python-ldap</screen>

    </sect3>
    </sect2>

</sect1>