Experimental evaluations of open-source Linux-based VPN solutions

Virtual private networks (VPNs) provide a low-cost alternative to leased lines and as such, are becoming increasingly popular among commercial and defense organizations for providing vital inter-office connectivity. Several commercial and open-source VPN products are now available that mainly differ in their capabilities to provide safe and secure services. In this paper, we study fifteen popular open-source Linux-based VPN solutions (OSLVs) and compare them with respect to network performances (bandwidth, delay and latency/jitter), supported features & functionalities (algorithm plug-ins and routing) and operational concerns (security and scalability). Experiments suggest that there is no single OSLV that excels in all the considered aspects and a combination of different solutions and/or tradeoff among desired characteristics may be required to deliver an optimal performance. Also network performance results suggest that OSLVs using UDP tunnels introduce 50% lower overhead, utilize 80% higher bandwidth and have 40-60% lower latency/jitter than those based on TCP