<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 &TC;;, bootup the

        operating system, and login as root user. Later, install the

        <quote>Dialup Networking Support</quote> group of packages

        available in the [base] repository of &TC;;. 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

        &TC;; 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>