Tenable has produced a set of plugins for our Passive Vulnerability Scanner (PVS) based on the publicly available SCADA IDS signatures from Digital Bond. This allows the PVS to discover which devices speak SCADA protocols in addition to more than 3000 other server and client vulnerabilities. This monitoring is done in real time and without any network impact. Along with Tenable's Security Center, Nessus scanner and Log Correlation Engine, this can become a very powerful tool for security monitoring of SCADA networks.
The Department of Energy recommends 21 separate activities for monitoring and securing SCADA networks. All of Tenable's products can be used together for a comprehensive analysis of SCADA network devices, protocols and traffic. Tenable also has published a paper (free for download) about how each of the DOE's 21 recommendations can be accomplished with Tenable active, passive and log analysis solutions.