The SCALANCE Security System provides protection for automation networks and security during data transfers between controllers on the factory floor through the use of hardware and software based technologies. The significance of information data and communication has increased rapidly over the past few years. Assaults on the integrity and availability of this data including sabotage on systems frequently results in enormous financial losses. Security in industrial communication network is different. The automation network could be connected to other networks within the Intranet or even with networks such as Internet or Wireless LAN. In addition to the general security of an office network, the following criteria correspond specifically to the industrial communication environment

• Protection of automation cells against interference
• Protection of network segments
• Protection against wrong access
• Scalability of security functionality
• No influence of network structure

Solutions: An approved method to secure networks is the use of a Firewall. A Firewall can be used also to protect the automation network from trespassing. It can be particularly recommended with relatively large networks, since the risk of trespassing rises sharply with an increase in the number of users. Another alternative and very secure way to protect the automation network is to use a VPN (virtual private network). An IPSec VPN, for example, offers authentication of communication partners, encryption of the messages and checking of data integrity