Datamonitor has predicted enterprise spending on firewalls and VPNs will approach $6 billion in 2007, doubling last year's figures.

Analyst Helen Toft said the largest growth is expected to be in the public sector, utilities and pharmaceutical sectors, driven by a demand for home working and mobile access, the report says, with particular emphasis on SSL VPN technology.

The US market is expected to drive the bulk of the growth, with spending of $2.6b. The fastest growth rate is expected in Latin America and Asia Pacific.