Security considerations for FAN-Internet connections

The interconnection between field area networks and IP-based LANs as well as the Intemet as a whole is becoming more and more popular. Emerging security issues have been neglected or underrated in the past. However, traditional security concepts that work well for LANs and the Intemet are hardly applicable to fieldbus systems. Based on an example from home automation, we review the problem and consider ways to prevent attacks both from the outside world and from within the fieldbus. Particular emphasis is given to firewalls, which are found to be of only limited value for securingfield-bus-Internet gateways. To tackle the security problem both on fieldbus level and in the Intemet, we propose the use of smart cards for authentication and encryption. We discuss modifications that are necessary to make field-bus nodes secure, why smart cards are “different ” and strategies to implement access control on the gateway. 1.