IT staffs under financial pressure to implement virtual servers may be overworked and lose the diligence to properly plan secure deployments, Corman says. "Virtualization requires more discipline and enforcement of policies than before," he says.

Virtual technology itself presents weak spots for attackers to take advantage of, he says. In particular, virtual environments are a "management nightmare" where each virtual machine may spawn another that could appear virtually anywhere. This makes instances of servers hard to find let alone protect, he says, and this "server sprawl" can lead to catastrophic failures, he said.

Individual virtual machines, called guests, can fall into vulnerable configuration due to a feature of virtualization that suspends them when they are not used, he says. When the applications these guests host are needed, they are brought back online, but in the meantime may have missed critical security updates and are left open to exploits.

Hypervisors that oversee virtual servers are designed to be small and simple to make them more difficult to attack. But they can be exploited according to publicly announced research, and that allows unlimited access to all the virtual machines they control, Corman says. "If they get into the hypervisor, the game is over," he says.

While grappling with the rigors of virtual security, show-goers were encouraged to embrace green networking principles, if not for actual costs savings then for the goal of reducing corporate carbon footprints.

"It's about efficiency as much as it is about anything else," said Johna Till Johnson, president and senior founding partner of Nemertes Research, of the dual-pronged impetus for green initiatives.

The drivers are there: Most servers use 50 percent of their rated power even when idle, so they're using 50 percent of electricity but doing 5 percent of the work, Johnson said.

That means that for every 100 servers only five are in use. Turning off the other 95 would result in 47.5 percent efficiency, she said. In addition, for every productive dollar gained from servers, almost two dollars are wasted in UPS, AC/DC conversions and fans, Johnson said.

Even so, 80 percent of companies recently surveyed by Nemertes have no corporate green policies; only 13 percent knew data center energy costs; only 3 percent turn off their servers when not in use; and desktops are left on 50 percent of the time.

Miami-Dade's public schools started a green initiative as a cost-saving measure. But it required the cooperation and support of the faculty and students at each school, said Paul Dunn, senior network analyst for the schools, said.