So it's not a rock-hard guarantee that traffic to localhost never leaves your system. It would be unconventional and uncommon for it to, though, except for the likes of us who like to ssh-tunnel all kinds of things on our loopback interfaces :-)
The sweet spot of security vs convenience, in the case of browsers and awarding "secure origin status" for .internal, could perhaps be on a dynamic case by case basis at connect time:
- check if it's using a self-signed cert - offer TOFU procedure if so - if not, verify as usual
Maaaaybe check whether the connection is to an RFC1918 private range address as well. Maybe. It would break proxying and tunneling. But perhaps that'd be a good thing.
This would just be for browsers, for the single purpose of enabling things like serviceworkers and other "secure origin"-only features, on this new .internal domain.
The secure context spec [1] addresses this-- localhost should only be considered potentially trustworthy if the agent complies with specific name resolution rules to guarantee that it never resolves to anything except the host's loopback interface.
[1] https://w3c.github.io/webappsec-secure-contexts/#localhost
If they're so worried about users getting duped to activate the insecure mode, they could at least make it a compiler option and provide an entirely separate download in a separate place.
Also, don't get me started on HSTS and HSTS preloading making it impossible to inspect your own traffic with entities like Google. It's shameful that Firefox is even more strict about this idiocy than Chrome.
Whose computer is this? I guess the machine I purchased doesn't belong to me, but instead belongs to the developer of the browser, who has absolutely no idea what I'm trying to do, what my background is and qualifications and what my needs are? It seems absurd to give that person the ultimate say over me on my system, especially if they're going to give me some BS about protecting me from myself for my own good or something like that. Yet, that is clearly the direction things are headed.
That is very much not true. Most corporate networks I've ever been on trust the internal network. Whether or not you think they should, they do.