ELA: a fully distributed VPN system over peer-to-peer network

In this paper, we propose a fully distributed VPN system over peer-to-peer(P2P) network called Everywhere Local Area network (ELA). ELA enables to establish private overlay network for VPN among nodes of a group without any servers. As opposed to the existing VPN systems, nodes of a group can build VPN without setting up a VPN server, and there is no problem of a single-source bottleneck and a single point of failure. Though it is known that VPN system using TCP as tunneling protocol does not work well, there are some nodes which can use only TCP because of NAT or Firewall. Therefore each node uses both UDP and TCP appropriately depending on the situation in ELA. The topology of ELA-VPN mitigates performance deterioration. We implemented a prototype of ELA on Linux, and show result of experimental latency between two nodes.