Cisco (CSCO) - Get Report continued its security push Monday, acquiring closely held Protego Networks for $65 million in cash.

The deal for the Sunnyvale, Calif., Internet security management system developer effectively rehires some of Cisco's former engineers. Protego founders Imin Lee and Partha Bhattacharya worked in security development at Cisco before starting Protego in 2002.

Cisco has acquired 11 companies this year. That's more deals than the San Jose, Calif.-based tech giant made the prior two years combined. Protego is Cisco's fifth security-related acquisition, and the deal comes as the top Internet gearmaker hopes to add more network defense software and devices to its hardware lineup.

With 38 employees at Protego, Cisco will pay about $1.7 million per worker. Cisco has increased its per-employee acquisition rates this year. In August, Cisco agreed to pay $200 million, or

$1.7 million per worker, for

P-Cube

, a network management shop.

Cisco shares were up 30 cents, or 1%, to $19.29 in early trading Monday.