Tip of the iceberg
Now project these problems to the IOT, Cloud Computing, and the amazingly large percentage of the IT community that believe the myth of unlimited bandwidth. It will not end well for anyone.
The commenters alluding to hardware security measures are on the right track. My understanding is that strong security features still incorporated in microprocessors, but that for commercial profit they are not used. My gut feeling is that information technology, as currently used and being deployed simply cannot be practically secured.
In simplistic terms, I can't secure things for things that I can't see and over which I have no control.
Unfortunately, as the following example shows, securing them is my legal responsibility.
Like a few hundred million or so people on the planet, I connect to the internet through a satellite ISP--that is, to say a metered, connection. (The fact that I had two systems connected through an Ethernet connection is a separate problem in its own right.)
During the few days or so that Microsoft's Windows 10 Anniversary update and subsequent patches downloaded, we burned through 15 GBytes of data usage, resulting in restricted access and more than doubling our monthly bill.
Here in italics is the response I got from the ISP.
. . . it's the customers responsibility for having a secured network and with what the data is used on. We provide plenty of information on our website to help with tips, but when it comes down to it, it's up to the customer how the data is consumed.
Me: Again, nonsense. When we selected the service and technologies we had the ability to do that.
Me: Subsequent changes and updates have eliminated the users ability to manage their systems.
Support Response: It's not nonsense. It's in your customer agreement that you have with [Company Name Deleted] I would suggest reading it at http://www.[deleted].com/legal
I deleted the company name. In fairness, they shouldn't be singled out for what, as near as I can tell, is a universal practice in the IT sector--Coercing acceptance of unilateral Terms and Conditions that effectively appropriate egregious rights to use of their customers' intellectual property (information) while relieving the IT providers of all legal responsibility for anything.
The problem is that bandwidth is NOT, wishful thinking to the contrary, unlimited. That's why, if you read the fine print, providers spec data transfer rates in terms of "up to" some limit. In the case of metered connections, the consequences of exceeding limits can be draconian, in dollar costs and in degraded or in some cases, suspended, connectivity.
The user has to choose between maintaining real-time security and maintaining acceptable service at a reasonable cost. (My ISP does provide an unmetered period, if I am willing to stay up until midnight every night and change the settings on all my devices. I consider that personal cost unreasonable.)
It is simply impossible to secure an internetworked system under these conditions. Promoting the pretext that it can is irresponsible and dangerous. Saddling the user with the responsibility may be legal, but it is morally reprehensible. The results are likely to be catastrophic.