Microsoft on Monday announced Azure Sphere, a new technology designed to protect the processors that power smart appliances, connected toys, and other gadgets.

Azure Sphere is powered in large part by Linux, a free operating system that Microsoft once viewed as a major threat.

It's the first time that Microsoft has made Linux part of a product offering.

Microsoft announced on Monday a new technology called Azure Sphere, a new system for securing the tiny processors that power smart appliances, connected toys, and other gadgets.

We'll get to the specifics in a moment, but here's the really notable part: To power Azure Sphere, Microsoft has developed a custom version of Linux, the free open-source operating system that Microsoft once considered the single biggest threat to the supremacy of its Windows software.

"After 43 years, this is the first day that we are announcing — and will be distributing — a custom Linux kernel," Microsoft's president, Brad Smith, said onstage at an event in San Francisco.

Smith said that by Microsoft's reckoning, the fact that most new gadgetry comes with a processor is cause for concern.

In 2016, unsecured cameras and other appliances were harnessed by bad guys to mount a massive cyberattack that took down major websites for hours. Two years later, people are still buying smart gadgets, but security hasn't always kept up.

Azure Sphere takes a combined approach to this problem, using hardware, software, and the cloud.

First, Microsoft has designed a more powerful kind of microprocessor that the company says it will make available to chip manufacturers for free.

Second, Microsoft has developed Azure Sphere OS, the Linux-based operating system that will run on those chips — Smith says that while Microsoft is a "Windows company," a full-fledged version of its flagship OS was too big and unwieldy for what it had in mind.

Third, the chip-OS combo will be integrated with an Azure Sphere cloud security service, designed to keep the devices up to date with security patches for at least 10 years.

Smith says the first Azure Sphere-powered hardware will hit the market later this year, with more details to come.

But, hey, Microsoft is making its own Linux! That's weird — and yet, it has been a long time coming.

When Satya Nadella took Microsoft's CEO job in 2014, one of the first things he did was announce that "Microsoft loves Linux." Since then, Microsoft has added robust support for Linux in its Azure cloud platform while letting developers integrate Linux with their copies of Windows 10.

In 2015, too, Microsoft developed a much smaller Linux-based technology as part of a larger open-source software package.

This, though, is the first time Microsoft developed a version of Linux and then made it the cornerstone of a product offering. It's just proof that anything is possible.