Understanding the client/server mode
The client/server mode was first introduced with OpenVPN 2.0. In this mode, the server is a single OpenVPN process to which multiple clients can connect. Each authenticated and authorized client is assigned an IP address from a pool of IP addresses that the OpenVPN server manages. Clients cannot communicate directly with one another. All traffic flows via the server, which has both advantages and disadvantages.
The advantages are as follows:
Control: The VPN server administrator can control which traffic is allowed to flow between clients. By default, no traffic is allowed to flow between clients. However, using either the OpenVPN option
client-to-client
or by using clever firewall and routing rules, it is possible to allow clients to communicate with each other.Ease of deployment: It is much easier to set up a single server that can be reached by many different clients than it is to ensure connectivity between a multitude of clients, each with their own...