I've been using zerotier for a year now. It is simply FANTASTIC. Currently use it as a management plane for my docker swarm. Really great work. Their blog is a

I've been using zerotier for a year now. It is simply FANTASTIC. Currently use it as a management plane for my docker swarm. Really great work. Their blog is also very much worth reading. EDIT: I'd like to mention an interesting feature. If you run two hosts that are also connected in another way, for example on a LAN, or using private networking from your cloud provider, ZT will automagically find and use the fastest route for host to host traffic.