Nebula is a Mesh VPN that has recently been open sourced by Slack Technologies, the developers of the instant messaging service Slack.
This is interesting for a number of reasons, one of which is Nebula was developed by Slack to connect their infrastructure accross regions without the overhead of a traditional VPN solution.
How is this relevant to us you might ask? Well instead of having devices connect directly to a centralized VPN server which handles all the connections, Nebula allows devices to connect directly to each other.
Wait! How does it do that?!?! Well that is the cool part.