On Mon, 9 Feb 2026 21:48:50 +0000 Brooks Davis <[email protected]> wrote:
> On Mon, Feb 09, 2026 at 10:09:04PM +0100, Guido Falsi wrote: > > On 2/9/26 21:49, Guido Falsi wrote: > > > On 1/28/26 11:00, Brooks Davis wrote: > > > > On Tue, Jan 27, 2026 at 03:35:16AM +0330, Pouria Mousavizadeh Tehrani > > > > wrote: > > > > > Hi everyone, > > > > > > > > > > With `net.inet6.ip6.use_stableaddr` now available, I believe we > > > > > should enable > > > > > it by default in CURRENT at least. > > > > > As you may already know, we currently use the EUI64 method for > > > > > generating > > > > > stable IPv6 addresses, which has serious privacy issues. > > > > > > > > > > IMHO, trying to maintain backward compatibility defeats the purpose > > > > > of a > > > > > privacy RFC. > > > > > > > > > > To be clear, we don't want to change the ip addresses of existing > > > > > servers. > > > > > However, it's reasonable for users to expect changes during a > > > > > major upgrade > > > > > (15 -> 16), a fresh install of a new major release, or living on > > > > > CURRENT. > > > > > So, for obvious reasons, changing the default value would not be > > > > > MFCed. > > > > > > > > > > What do you think? > > > > > > > > I wonder if we should ship an update to 15 (landing in 15.1) explicitly > > > > adding net.inet6.ip6.use_stableaddr=1 and a suitable comment to > > > > /etc/sysctl.conf so people who later upgrade to 16 aren't painfully > > > > surprised when their server disappears.?? New installs of 16 would get > > > > the new default, but upgrades would keep the old default.?? The downside > > > > would be that people who have edited sysctl.conf would have a merge > > > > conflict to resolve, but that's a fairly normal thing. > > > > > > > > -- Brooks > > > > > > > > > > > > > Hi all, I just committed the change in the default (thanks to zlei for > > > approving it, and all the reviewers). [1] > > > > > > > > > I'll also send an heads up to current@ and net@ just in case. > > > > > > > > > I am replying t this specific message in the thread because I do like > > > brooks' idea on how to introduce this on stable. > > > > > > Once I get the MFC approved and committed [2], I could send a further PR > > > implementing such a change on stable/15 sysctl.conf. > > > > While writing my heads up message I just noticed this plan cannot work, > > unluckily. > > > > Due to the nature of the sysctl, enabling it via /etc/sysctl.conf would > > cause > > the change to only affect interfaces created after sourcing the file. This > > means that for most machines the default interface would be unaffected and > > keep the default to the in kernel one. > > > > To achieve the effect Brooks suggests would require the "soft switch" to > > happen via loader.conf. Not sure if this is a good idea though. > > I think all my reasoning still applies to loader.conf. IMO, people are > going to be really upset if they miss a release note that causes their > system to be inaccessable via IP. Even with proper remote access, it's > super annoying to fix (having done this to myself many times by many > means). > > -- Brooks Looking into the diff, use_stableaddr is defined as CTLFLAG_RWTUN in sys/netinet6/in6_proto.c. So (not tried though, as I cannot obtain RA from my local ISP, thus, not configured for IPv6) /boot/loader.conf should work as it's tunable, too. To avoid race conditions, /boot/loader.conf should be preferred and RELNOTE (and UPDATING, too?) for this should be based on /boot/loader.conf case. Regards. -- Tomoaki AOKI <[email protected]>
