San Mateo-based Untangle, a venture-backed provider of networking software, said today that the firm has launched its Re-Router Technology. The firm said its technology allows Windows desktops to perform tasks like blocking spam, spyware, and viruses from corporate networks. The software--which is available for free through open source--is targeted at helping small businesses manage their network security without requiring external hardware. Untangle is venture backed by CMEA Ventures and Rustic Canyon Partners, and was formerly known as Metavize.