Really happy with Hamachi. Started out marketed as a gaming tool, but LogMeIn remarketed it correctly as a real virtual network solution.

Saved my &*s on several occasions allowing me to connct to a 'non-Internet' facing server.

Does not really have an enterprise feel to it and wonder if it ever will. It also lacks an open protocol description and/or clients on iOS or Android. However, an older build for ARM/Maemo is available. The lack of this limits it currently to a Windows and Linux environment.

The idea with protocol was always to keep the handshake/authentication part open, but don't commit to the details of the application client-server messaging. To that end the protocol spec for the original version was available from the moment the system went live and it was detailed enough so that some people made a sniffer and started reversing the application layer (which was fine with me). After the LogMeIn acquisition we revised the handshake protocol a bit to allow for security parameter negotiation and re-negotiation, and the spec again was published. It should still be there on the website, but I don't have a URL at hand.

Also, I wasn't involved with Hamachi for few years now, but I think they had a plan to switch to TLS altogether, so that must've been done by now.

Yeah, from looking at it (I haven't installed it yet), the Logmein purchase and adaptation seems to make it a lot more interesting (I think I do vaguely remember it as a gaming thing back in the day when IPX was a thing)

I wonder if Salesforce, Oracle, Microsoft Azure, etc. would be likely to do some kind of virtual/software defined network thing in the future. It's an obvious choice for an IaaS provider, but being able to put your SaaS or PaaS on a customer-defined network makes a lot of sense too. Would love to talk to those guys.

It wasn't a "gaming thing".

It was indeed widely used in gaming circles, but gamers weren't really the target market I designed it for. They just happened to come along in droves, because I added support for network broadcasts and that made LAN games playable over the internet.