56. Chapter - Solving IP Address Conflicts in VPNs Through NAT

56.1. The Problem

All IP communication is based on the assumption that IP addresses are uniquely assigned and that no two clients or networks use the same IPs. However, since IPv4 addresses are scarce, addresses from the 192.168.0.0/16,172.16.0.0/12 and 10.0.0.0/8 ranges are normally used in local networks for this purpose. Since everyone can freely choose their addresses from these areas, conflicts can easily occur.

If two networks with the same or overlapping IPs are to be connected via VPN, the IPs are no longer unique and the VPN will not function.

To solve this problem, the Intra2net system offers the facility to rewrite IPs at input and output from the VPN (Network Address Translation, NAT). This means that the peer can always be reached via a different network range. The addressing is once again unique and the conflict is resolved.