Another advanced use case of a dedicated point-to-point VPN is to bridge two remote network segments together. OpenVPN allows you to bridge two network segments with the same IP address range together to form a single transparent network segment. It is generally not advisable to do this, as the performance of such a bridged network will not be optimal. In some cases, it is unavoidable. Normally, it would be better to assign different subnets to both ends, but sometimes special software is tied to a specific IP address and there is no alternative but to have the same subnet on both ends.
Consider the following network layout:
At the client-side, the network 192.168.4.0/24 is in use—with the OpenVPN client found at 192.168.4.128. At the server side, the same subnet is in use—with the OpenVPN server found at 192.168.4.65. The goal is to bridge the two networks together, so that all machines on both ends can see each other transparently.
dev tap mode OpenVPN...