Tinc - a VPN daemon

tinc is a Virtual Private Network (VPN) daemon that uses tunnelling and encryption to create a secure private network between hosts on the Internet. All traffic is optionally compressed using zlib or LZO, and LibreSSL or OpenSSL is used to encrypt the traffic and protect it from alteration with message authentication codes and sequence numbers.

VPN traffic is always (if possible) sent directly to the destination, without going through intermediate hops. As long as one node in the VPN allows incoming connections on a public IP address (even if it is a dynamic IP address), tinc will be able to do NAT traversal, allowing direct communication between peers.