SonicWALL has updated its proprietary firmware with SonicOS 4.0 Enhanced. Designed to operate on all SonicWALL firewall appliances, including the System i-compatible Pro 4100 VPN appliance, SonicOS 4.0 offers unified threat-management protection based on reassembly-free deep-packet inspection capabilities. New features include an application firewall, failover with state synchronization, high availability, single sign-on, and inbound load balancing. Additional highlights include HTTPS content filtering, a services dashboard, and virtual access points.