The StoneGate Firewall engine is based on Multi-Layer Inspection technology that combines both stateful and application-level inspection technology to control connectivity and information flow between internal and external networks. It provides Network Address Translation (NAT) to keep internal network addresses private. The VPN security services are based on the IPSec standard and allow users multiple cryptographic support options. As part of a firewall cluster, the StoneGate Firewall engine provides a high availability feature, so that component firewall failures degrade the cluster to a fully functional and secure state.