ZyXEL Communications PLA-470 V2 - V3.0.5 Instalační příručka stáhnout pdf (Strana 279)

According to the manufacturers of PLC devices and to the PLC technologies, it is

more or less possible to configure advanced security functionalities. Table 11.5 sum-

marizes the main security functionalities of the various PLC technologies.

VLAN (Virtual LAN)

As its name indicates, a VLAN (virtual LAN) is used for defining virtual local area

networks. This technology, which has appeared for several years in Ethernet net-

works under the IEEE 802.1Q standard, enables the coexistence of several virtual

local area networks over the same Ethernet connection.

Most corporate switches propose this solution, which is to graft a PLC network

onto an existing Ethernet network. By creating two virtual local area networks, one

for the Ethernet network and the other specifically dedicated to PLC, this solution

results in the topology illustrated in Figure 11.8, in which both networks are sepa-

rated by a firewall.

The PLC VLAN is based on the use of multiple network keys (NEK in the case of

HomePlug) or of networks from various technologies (a HomePlug network and a

DS2 network, for example). HomePlug supports the propagation of VLAN labels

that can be configured on the switches of the company Ethernet network.

Virtual Private Networks (VPN)

As we have seen for PLC home networks, the VPN (virtual private networks) repre-

sent the most reliable way to make a PLC corporate network secure. For this pur-

pose, they are based on a client-server architecture in which the client is the station

connected to the PLC device and the server a dedicated computer.

Since this solution is detailed in Chapter 10, we do not go back to it here.

Although the project is now fixed, FreeSWAN is the reference VPN open source

solution. It is available at the following address: http://www.freeswan.org.

Installing and Configuring a PLC Repeater (Bridge)

As indicated before, the PLC signal propagates over the electrical wirings and is sub-

jected to a significant attenuation due to the cable resistance and to the electromag-

netic disturbances caused by the electrical devices connected to the electrical

260 PLC for Businesses

Table 11.5 Security Functionalities of PLC Technologies

PLC TECHNOLOGY SECURITY FUNCTIONALITY

HomePlug

1.0, Turbo NEK (DES 56 bits)

NEK, NMK, DAK (AES-128 bits + key rotation)

AsokaUSA

NEK, filtering by MAC address and IP address of the devices

connected to the PLC network, password on the HTTPS

configuration interface

DS2

Exchange of master-slave keys, filtering of MAC and IP addresses,

password on the HTTP configuration interface

Spidcom Exchange of master-slave keys

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ZyXEL Communications PLA-470 V2 - V3.0.5 Instalační příručka Strana 279