Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. VPN-1 is a firewall and VPN product developed by Check Point Software Technologies Ltd. VPN-1 is a stateful firewall which also filters traffic by inspecting the application layer. It was the first commercially available software firewall to use stateful inspection. Later, Check Point registered U.S. Patent # 5,606,668 on their security technology that, among other features, included stateful inspection. VPN-1 functionality is currently bundled within all the Check Point's perimeter security products. The product, previously known as FireWall-1, is now sold as an integrated firewall and VPN solution. VPN-1 is one of the few firewall products that is still owned by its creators. By contrast, most other commercial firewalls such as Cisco PIX and Juniper NetScreen were acquired by their present owners.