Before attending two recent M2M conferences in Düsseldorf and Berlin, I probably wouldn't have recorded this episode. But as I see it, there's quite a bit of fear-driven "black magic" security pixie-dust applied to industrial scenarios in form of stacking up layers of hardware boxes, and "VPN" is often used and understood as a synonym for a comprehensive security solution, while vendors in this space who don't use VPN and rely on straightforward direct and secure connections are met with skepticism.
So in order to get everyone who follows the series on the same level of understanding, this 5th episode is specifically for the folks on OT (operational technology) side of the IT/OT divide. I'm talking about VPN and what it is and what it isn't, how it adds security and how it doesn't, and I'm talking about the range of link, network, and transport layer security protocols that readily available for solutions today and that you're likely relying on these exact protocol suites with any VPN solution you buy magic hardware boxes for.
If you're in IT, you may like this as a refresher. In the next episode I'll cover the next set of security aspects like authentication and authorization, so you get one more security theory episode than I though I'd do.