Companies are also waking up to the fact that security appliances can be much easier to manage than software.

Some 20 percent of these appliances cost more than $25,000, compared with just 10 percent in the second quarter, according to IDC's figures.

"Until now, we have been saying (security appliances) are perfect for small enterprises and branch offices," said Carla Arend, research analyst for European security products and strategies at IDC. "But now for the first time, we are seeing them increasingly sold to large enterprises."

There are several reasons, Arend said: reduced complexity, lower installation costs, easier management, easier troubleshooting and lower cost of ownership, compared with buying software alone.

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