Today's accomplishment: got sufficiently irritated by Go failing self-tests on stock FreeBSD systems that I finally filed a report on the second issue: https://github.com/golang/go/issues/77411
The first issue on stock FreeBSD is https://github.com/golang/go/issues/70702
It's very obvious that approximately nobody runs Go's all.bash on real FreeBSD systems. At best it is "tested" on Go's builder machines, which are clearly non-standard in multiple ways.
My "Go failing selftests for its net package on FreeBSD" issue¹ turns out to be specific to FreeBSD 15. Evidently there's some networking change that is doing something different from what Go is counting on. If I'm energetic, I can peruse FreeBSD changelogs and stuff.
(It's possible all of the failures involve IPv6 / IPv4 interactions.)
I believe I've found the FreeBSD 15 networking change that breaks Go's net package self-tests, and it's an interesting one¹. As described in the release notes²:
Making a connection to INADDR_ANY, i.e., using it as an alias for localhost, is now disabled by default. This functionality can be re-enabled by setting the net.inet.ip.connect_inaddr_wild sysctl to 1.
I can see the point, even though this is a behavior change.
¹ https://cgit.freebsd.org/src/commit/?id=cd240957d7ba
² https://www.freebsd.org/releases/15.0R/relnotes/#network-general
For proper credit (or if you prefer, blame), I learned about 'ssh 0' from a comment @lyda left on my techblog. But now that I've seen it I can't unsee it. What else will accept '0' as a hostname? Feel free to try it today.
(Firefox will, it looks like.)
Bonus round: this 'ssh 0' behavior also works for the IPv6 equivalent, 'ssh ::0' or 'ssh ::'. That means it will probably also work in browsers.
Surprise: blocking DNS rebinding to localhost requires screening out more than 127/8 and ::1 answers. This is my face.
Chris Siebenmann