However, writing software without defects is not sufficient. In my experience, it is at least as difficult to write software that is safe - that is, software that behaves reasonably under adverse conditions.

My reply is: the software has no known bugs, therefore it has not been updated.

Sure, but competition is good for the user.

Coming back to the topic of computer security, the TCP Wrapper is an example of such a safety net. I wrote it when my systems were under attack by someone who appeared to walk through walls.

I don't expect an overnight change of all desktops to what the US Military used to call B3 level security. And even that would not stop users from shooting themselves into the foot.

This will surprise some of your readers, but my primary interest is not with computer security. I am primarily interested in writing software that works as intended.

Most of the effort in the software business goes into the maintenance of code that already exists.