Expand rdomain option to support FreeBSD fib

[Damien Miller]

On Fri, 11 Jul 2025, Christian Weisgerber wrote:

> Paige Thompson via openssh-unix-dev:
> 
> > Could I or somebody add this in a future release?
> 
> That might be relatively simple, see this patch that replaces OpenBSD
> rdomain with FreeBSD FIB support in OpenNTPD:
> 
> https://cgit.freebsd.org/ports/tree/net/openntpd/files/patch-src_server.c
> 
> (I don't have any time to work on this myself.)

That looks very straightforward. Someone just needs to implement
sys_get_rdomain() and sys_set_rdomain() for FreeBSD in OpenSSH's
openbsd-compat/port-net.c

-d