Virtual Private Networks (VPNs) are used to interconnect local networks over the Internet. This involves the routing of the private LAN IP addresses via an Internet connection between two gateways with public IP addresses.
For the secure routing of private IP addresses over the Internet, a VPN connection, also known as a VPN tunnel, is established between the two LANs.
The VPN tunnel has two important tasks:
- To shield the transported data from unauthorized access
- To route private IP addresses via an Internet connection that can normally only be used to route public IP addresses.
The VPN connection between the two gateways is defined by the following parameters:
- The end-points of the tunnel, the VPN gateways, each of which are accessible via public IP addresses (static or dynamic)
- The IP connection between the two gateways
- The private IP address range that are to be routed between the VPN gateways
- Setting relevant to security, such as passwords, IPSec keys etc. to shield the VPN tunnel
This information is contained in the so-called VPN rules.
