. ZyXEL USG 20 Unified Security Gateway Appliance for 1-5 users - 5 Gigabit Ethernet ports USB2.0 port Stateful Firewall 2 IPSec VPN tunnels SSL VPN Anti-Spam and Optional ConteThe ZyWALL USG (Unified Security Gateway) 20 is the third generation ZyWALL featuring an all-new platform. It provides greater performance protection as well as a deep packet inspection security solution for small businesses to enterprises alike. It embodies a Stateful Packet Inspection (SPI) firewall Content Filtering Anti-Spam and VPN (IPSec/SSL) in one box. This multilayered security safeguards your organisation\'s customer and company records intellectual property and critical resources from external and internal threats..