This paper addresses design principles and best practices regarding the secure implementation and operation of Wireless LAN (WLAN) communication networks based on the IEEE 802.11 protocol. First, a general overview of WLAN technology and the 802.11 standard is provided. The subsequent sections describe the various initial and interim IEEE security standards leading to the 802.11i standard. An explanation of the 802.11i standard for securing WLAN networks is then presented, followed by principles for designing secure WLAN networks, and a list of specific security best practices that can be used as a guideline for organizations considering the deployment of a WLAN. Finally, a section on technical issues and special considerations for installations of WLAN networks in industrial environments is presented. A concluding section summarizes key points and is followed by a list of online technical references related to the topics presented.

The Supervisory Control and Data Acquisition (SCADA) system of a natural gas utility was compromised resulting in a reduction of operation. The breach was discovered when operator interfaces became unresponsive and the system was no longer acquiring data. As a result, the system was disconnected from the network and a combination of manual operation overrides and limited fail-over to a backup server went into effect until the environment could be restored. Technicians troubleshooting the incident identified the deletion of several core application files on the primary control server as the source of the problem.