ZyXEL Communications PLA-470 V2 - V3.0.5 Guía de instalación descargar pdf (Pagina 251)

Hardware firewalls must be installed on the computer connected to the Internet.

This is ideally a dedicated computer, such as the access gateway defined above (see

Figure 10.17).

VPN and PPPoE

The only way of guaranteeing the total security of a PLC network consists of using a

VPN (virtual private network) as explained in Chapter 4.

The use of an authentication server is only necessary if the network requires a

high level of protection. The authentication scheme is used, as its name implies, for

reliably authenticating any user who wants to connect to the network. RADIUS

(remote authentication dial-in user server of which a free version called

“Freeradius,” is available at the following address: http://www.freeradius.org, is the

most widespread authentication protocol).

To protect a network on an even higher reliability level, a VPN is essential.

VPNs are used for fully protecting PLC network links by means of authentication

and encryption mechanisms. At present, IPsec is the most widespread protocol in

VPN. However, the use of an IPsec VPN requires rather powerful computers. It also

requires the client computers to have the configuration required by their VPN client.

Using authentication servers or VPN servers requires the adding of the corre-

sponding functionalities coinciding with the level of a specific gateway in case the

gateway for accessing the Internet already incorporates a DHCP server and an NAT

router, as illustrated in Figure 10.18.

232 PLC in the Home

Figure 10.14 Windows XP network connection window

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ZyXEL Communications PLA-470 V2 - V3.0.5 Guía de instalación Pagina 251