On Wed 20 Jan 2021 at 14:46:31 (+0100), Marc SCHAEFER wrote: > > I experiment [experienced] a change of behaviour between the kernel of Debian > jessie > and Debian buster. > > Namely, before, ping6 fe80::1 would fail, since it is ambiguous (fe80::1 > is a link scope, thus a zone/interface scope ID is required). > > With buster, it tries the first Ethernet interface, no error (unless > NDP does not find it, obviously). > > The correct behaviour when specifying the zone (interface scope ID) is > the same on both versions: > > ping6 fe80::1%eth0 # e.g. > > Is there something broken with my setup, or has something changed in the > way the Linux kernel behaves when the required zone (interface scope ID) > is not specified ? > > I found the idea of reporting an error when a scope is not given very > correct, simple and pedagogic (aka jessie behaviour).
I'm not convinced that reporting an error would be correct. I think, rather, that it should use the interface that it considers "nearest". On success, it will continue to use that interface; on failure, it will try others in round-robin fashion to find one that works. That's desirable behaviour for the packets themselves, is it not. As far as the address is concerned, fe80::1 is perfectly formed, but ambiguous. Is that what your jessie error message used to say? Cheers, David.
