<sect1 id="server-usage-connections">

    <title>Administering Dial-Up Connections</title>

    <para>

        The lifetime of dial-up connections must be limitted based on

        the number of users you expect to establish connection and the

        kind of services you plan to provide. The mail service

        provided by the server computer is conceived as a public

        service so anyone with a modem attached to a computer would be

        able to have access to it.  However, due to hardware

        limitations, only 100 users will be allowed to be registered

        in the public mail service. Based on this information, the

        lifetime of established connections will be of 15 minutes from

        the established moment on. Once the connection has been

        established, if the link is idle for 1 minute, the server

        computer will close the established connection to free the

        telephone line.  This control can be implemented through the

        <option>maxconnect</option> and <option>idle</option> options

        inside the <application>pppd</application>'s configuration

        file.

    </para>

    <para>

        Only registered user profiles will be able to establish connections

        to the server computer.  This control can be implemented using

        the <option>allow-number</option> option in the

        <application>pppd</application>'s configuration file to define a

        list of all telephone numbers that are allowed to establish

        connection with the server computer, based on the list of

        registered user profiles.  By default, all telephone numbers

        are denied from establishing access with the server computer,

        except those ones explicitly set by

        <option>allow-number</option> option.  If the

        <option>allow-number</option> option is not present in

        <application>pppd</application>'s configuration file, all

        telephone numbers are allowed to establish connection with the

        server computer, so be sure to include the

        <option>allow-number</option> option in

        <application>pppd</application>'s configuration file if you

        want to control who can/cannot establish connection with the

        server computer.

    </para>

<screen>

##### centos-pppd-config will overwrite this part!!! (begin) #####

allow-number 12345

allow-number 21345

allow-number 34567

##### centos-pppd-config will overwrite this part!!! (end) #####

</screen>

    <para>

        The <application>centos-pppd-admin</application> application

        must be considered part of user profile registration process

        inside the server computer. The

        <application>centos-pppd-admin</application> application would

        be used to control the list of allowed telephone numbers

        inside the <application>pppd</application>'s configuration

        file, based on the list of user profiles. The

        <application>centos-pppd-admin</application> application

        should be executed after any registration/deletion action

        against the list of user profiles with 

        class="username">root</systemitem> privilages in order to be

        able of writing the settings on

        <application>pppd</application>'s configuration file.

    </para>

    <para>

        Redialing consecutive connections from the same telephone

        number without any dealy between call retries must be avoided

        from client computers. This would reduce the possibilities for

        other client computers to establish connection with the server

        computer. To prevent this issue from happening, it would be

        necessary to provide more telephone lines than users

        authorized to establish connection with the server computer.

        Nevertheless, there is only one telephone line available for

        the server computer to use.

    </para>

</sect1>