Gnu Virtual Private Ethernet
VPE creates a virtual ethernet (broadcasts supported, any protocol that works with a normal ethernet should work with VPE) by creating host-to-host tunnels between multiple endpoints.
Unlike other virtual private "network" solutions which merely create a single tunnel, VPE creates a real network with multiple endpoints.
It is designed to be very simple (cipher selection done at compile time etc.), and easy to setup (only a single config file shared unmodified between all hosts).
Vpn hosts can neither sniff nor fake packets, that is, you can use MAC-based filtering to ensure authenticity of packets even from member nodes.
VPE can also be used to tunnel into some vpn network using a variety of protocols (https-proxy, tcp, udp, rawip, icmp-tunneling). It is, however, primarily designed to sit on the gateway machines of company branches to connect them together.