Virtual private networks (VPNs) create tunnels that allow users/systems to connect securely over a public network, as if they were connecting over a local area network (LAN). To set up a VPN tunnel, you need a pair of devices that can authenticate each other and encrypt the flow of information between them. The devices can be a pair of Palo Alto Networks firewalls, or a Palo Alto Networks firewall along with a VPN-capable device from another vendor.