Cisco’s appetite needed feeding again so it’s buying ScanSafe Inc, the 10-year-old software-as-a-service (SaaS) web security house, for $183 million in cash and retention-based incentives.

It’s already got on-premise content security provider IronPort and is supposed to bring together IronPort’s high-performance web security appliance and ScanSafe’s widgetry, which blocks malware and secures the use of the web and messaging.

ScanSafe’s stuff is supposed to be fit for everyone from the global enterprise to small businesses.

Cisco said ScanSafe’s service will be integrated into its AnyConnect VPN Client, its newest virtual private network (VPN) product, to concoct a secure mobility solution. And ScanSafe’s global network of carrier-grade data centers and multi-tenant architecture is supposed to enhance Cisco’s ability to provide cloud security.

Web security is expected to grow to $2.3 billion by 2012 and IDC reckons ScanSafe has upwards of 30% of the worldwide SaaS Web Security market, more than any other vendor in the sector.

Once the acquisition closes, which is expected to happen by January, ScanSafe will become part of Cisco’s Security Technology Business Unit (STBU) run by general manager Tom Gillis, who has a vision of a “borderless network security architecture that combines network and cloud-based services.”

ScanSafe was backed by Montagu Newhall Associates, Balderton Capital and Scale Venture Partners to the tune of $43.5 million. It just picked up its $13.5 million C round in March.

The company just discontinued Scandoo, a free service that provided advanced warning for security risks and offensive content in search engine results.

Cisco has spent over $6 billion buying this and that the last month.