A VPN (Virtual Private Network) is established to connect two local networks (intranets) securely over the Internet securely. The VPN routers manage authentication between servers and clients and handle data encryption for the connection. Only authorized users may access the network and the data exchange cannot be intercepted. A VPN includes authentication and encryption to protect data integrity and confidentiality. VPNs are "virtual" in the sense that individuals can use the public Internet as a means of securely accessing another private network. Once the VPN connection is established, users have access to the same network resources, addresses, and so forth as if they were connected locally. VPNs are "private" because the data is encrypted between two VPN gateways. Encryption makes it very difficult for anyone to intercept data and capture sensitive information such as passwords.
Establishing a VPN requires the functionality of a VPN gateway on each side of the communication line. An intelligent Internet access router, e.g. Quadro, delivers this function, but also PCs or workstations can be equipped with VPN gateway functionality.
VPN connections are - like every Internet connection - based on IP addresses, what means, that the concerned VPN gateways will have to authenticate the IP address of their respective partner VPN gateways. And each time a specified VPN shall be opened, the same IP addresses are expected normally. That fact won't cause any problems, if both VPN partners have fixed WAN IP addresses at their disposal. But there may be good reasons to prefer dynamically allocated IP addresses. To enable devices that use a variable IP address to become part of a VPN, they are turned into so-called Road Warriors. Then they are able to reach e.g. their corporate network via authentication at the company's VPN gateway device. This VPN gateway device has to have a fixed IP address for Internet access, because every VPN needs at least one VPN gateway device with a fixed IP address.
The partner devices of a VPN must have different WAN IP addresses - and, if they are connected to local area networks, these LANs have to have different IP addresses. As all Quadro devices in delivery status have the same default IP addresses, at least one of them has to be configured in order to set new IP addresses.