In a move further underlining the convergence of networking and security, Cisco said it will buy Perfigo for $74 million in cash.

Perfigo's network admission control products are designed to keep worms and viruses from wriggling into networks and wreaking havoc.

Its CleanMachines offering recognizes users and their devices and roles; evaluates the security posture of the endpoint and scans for vulnerabilities; and enforces policy in the network.

The San Francisco firm, which is privately held and venture-backed by Greylock, counts small and medium business, as well as colleges and universities, among its customers.

Elizabeth McNichols, a Cisco spokeswoman, said Perfigo is the company's third security acquisition in the past year.

The purchase is expected to close during the second quarter of Cisco's fiscal year 2005, which ends Jan. 29. Perfigo's 31 employees will become part of Palmer's security group, McNichols said.

In the interim, Cisco has licensed Perfigo's CleanMachines and will make it available to customers this month.

For Cisco, it's the latest buy aimed at strengthening network security, something customers of all sizes have identified as a priority. Last year, it paid $154 million in stock for intrusion detection software maker Okena.

Okena's technology helps identify security risks by analyzing operating systems, file systems, configuration and network requests.

Cisco's closest competitor, Juniper Networks , has not stood pat. It's biggest move was to acquire security and access technology specialist NetScreen for $4 billion in stock.

In other efforts on the security front, Cisco and Microsoft announced this week that they would integrate technologies and push for an industry standard to power network security and health policy compliance.