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Tue, 27 Jan 2026 11:17:19 -0800 (PST) Received: from mutt-hbsd ([2001:470:4001:1::95]) by smtp.gmail.com with ESMTPSA id 006d021491bc7-662f99447b5sm204653eaf.2.2026.01.27.11.17.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Jan 2026 11:17:18 -0800 (PST) Date: Tue, 27 Jan 2026 19:17:18 +0000 From: Shawn Webb To: Guido Falsi Cc: freebsd-current@freebsd.org Subject: Re: we should enable RFC7217 by default Message-ID: X-Operating-System: FreeBSD mutt-hbsd 14.3-STABLE-HBSD FreeBSD 14.3-STABLE-HBSD HARDENEDBSD-14-STABLE amd64 X-PGP-Key: https://git.hardenedbsd.org/hardenedbsd/pubkeys/-/blob/master/Shawn_Webb/03A4CBEBB82EA5A67D9F3853FF2E67A277F8E1FA.pub.asc References: <9cda2fbc-b8fb-44d1-8c1f-88395d741af7@FreeBSD.org> <0f5fcd3d-b189-49f5-ac81-d4fb48d90a77@FreeBSD.org> List-Id: Discussions about the use of FreeBSD-current List-Archive: https://lists.freebsd.org/archives/freebsd-current List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-current@FreeBSD.org MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="oyz6roa7m34yy3ab" Content-Disposition: inline In-Reply-To: <0f5fcd3d-b189-49f5-ac81-d4fb48d90a77@FreeBSD.org> X-Spamd-Bar: ---- X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[]; ASN(0.00)[asn:15169, ipnet:2607:f8b0::/32, country:US] X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Rspamd-Queue-Id: 4f0wC95XJrz3H8F --oyz6roa7m34yy3ab Content-Type: text/plain; protected-headers=v1; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: we should enable RFC7217 by default MIME-Version: 1.0 On Tue, Jan 27, 2026 at 07:27:28PM +0100, Guido Falsi wrote: > On 1/27/26 19:17, Shawn Webb wrote: > > On Tue, Jan 27, 2026 at 03:35:16AM +0330, Pouria Mousavizadeh Tehrani w= rote: > > > Hi everyone, > > >=20 > > > 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 genera= ting > > > stable IPv6 addresses, which has serious privacy issues. > > >=20 > > > IMHO, trying to maintain backward compatibility defeats the purpose o= f a > > > privacy RFC. > > >=20 > > > To be clear, we don't want to change the ip addresses of existing ser= vers. > > > However, it's reasonable for users to expect changes during a major u= pgrade > > > (15 -> 16), a fresh install of a new major release, or living on CURR= ENT. > > > So, for obvious reasons, changing the default value would not be MFCe= d. > > >=20 > > > What do you think? > >=20 > > I think this would be a good step for FreeBSD. In HardenedBSD, we set > > net.inet6.ip6.{prefer,use}_tempaddr to 1, which creates completely > > random IPv6 addresses (scoped to the prefix, of course). > >=20 > > The one thing I would hope is that support for completely random IPv6 > > addresses via SLAAC does not go the way of the dodo. > >=20 > > (If net.inet6.ip6.use_stableaddr becomes the default, we will likely > > keep it at 0 in favor of the other aforementioned sysctl nodes.) >=20 > Those are two orthogonal things. >=20 > stableaddress enabled replaces the current algorithm for deriving the main > interface address, that stays attached to the interface indefinitely. >=20 > tempaddr creates additional addresses for the interface that are used (and > preferred if the prefer flag is enabled) for outgoing connections, and are > generated again periodically, with old ones remaining attached to the > interface, since old connections could still use them, till reboot. >=20 > The two can live together, there is no reason to disable one of them. >=20 >=20 > BTW while developing my patch, in one of the first iterations, I did break > the tempaddr mechanism, so I can assure you I took special care for them = to > not interfere with each other. Seems I was indeed a bit confused. Thank you for the explanation. So looking at one of my current SLAAC systems, I see: =3D=3D=3D=3D BEGIN LOG =3D=3D=3D=3D bridge0: flags=3D1008843 m= etric 0 mtu 1500 options=3D10 ether 58:9c:fc:10:d7:7e inet 192.168.1.251 netmask 0xfffff000 broadcast 192.168.15.255 inet6 fe80::5a9c:fcff:fe10:d77e%bridge0 prefixlen 64 scopeid 0x3 inet6 2001:470:4001:1:5a9c:fcff:fe10:d77e prefixlen 64 autoconf plt= ime 14400 vltime 86400 inet6 2001:470:4001:1:c001:f868:c587:cdd7 prefixlen 64 deprecated a= utoconf temporary pltime 0 vltime 44033 inet6 2001:470:4001:1:c139:85be:79b3:e3ec prefixlen 64 autoconf tem= porary pltime 12610 vltime 86400 id 00:00:00:00:00:00 priority 32768 hellotime 2 fwddelay 15 maxage 20 holdcnt 6 proto rstp maxaddr 2000 timeout 1200 root id 00:00:00:00:00:00 priority 32768 ifcost 0 port 0 bridge flags=3D0<> =3D=3D=3D=3D END LOG =3D=3D=3D=3D =46rom what I understand now, the only thing that would change is the 2001:470:4001:1:5a9c:fcff:fe10:d77e address. Instead of incorporating the MAC address in that IP address, it would be the stableaddr address. Amy I understanding that correctly? Thanks, --=20 Shawn Webb Cofounder / Security Engineer HardenedBSD Signal Username: shawn_webb.74 Tor-ified Signal: +1 303-901-1600 / shawn_webb_opsec.50 https://git.hardenedbsd.org/hardenedbsd/pubkeys/-/raw/master/Shawn_Webb/03A= 4CBEBB82EA5A67D9F3853FF2E67A277F8E1FA.pub.asc --oyz6roa7m34yy3ab Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEA6TL67gupaZ9nzhT/y5nonf44foFAml5DzcACgkQ/y5nonf4 4frOnw/+Mz23x5L4cwWKgFFvG8vvI1wsPXRbBImUH8udnzClfB4sY9iCoFPy25tR ZcVEzKyrVwb0fQXiYHj8F9QuGry6U3uEzk2g8k6B2jcYkU8oE86Gy2z5B6kt3Nlk 3vmN/8MjK8b3VEoYKwoTi5ZP2H1l/r1sXio+LXWosjI1we5jb0r+JTGu+KE23Wc9 uAv0PXpvdUlV14cV26boD0eLYxEP62HoruBuwGX7AyRX7mlX4On+di/RKpnr1WlD NLDW+qGrvBq9jAISwHY3zJtBUn63T4SSI051ZW7micNy9AMMmBsf8R73UxQn1ZE/ jOXJiqbqZ9pwf07ruTcAAeyVjSQhK/k4T740b6vpfenv38oG0MdwDH+m3fj8psad xF8n9tH1o2A0hPukC8pAS/rQC555oCiJ9Qkwz/sFhv42Qs0KmoblXwuc/t5Wl6xI /3VXItOgRkzCyd5tSV75Qd0nH38DvYe9jMtP8V0A+7WJBws81EWzXkc5T5VlZM/v 2+xOMDR5KRAxpug5DhRKHXlucXzyyHcne9P2yVR6SZ8zQ+Erp/xYWj9QbysY00TB MhmiSujbUuwb3VSURNvrcwlAEBwrX3wbgN8zd/Mp52uchJ4ZxOlbH2WzrtHndET1 Y34QAXi3OzEgzoSyEmN2btRpq65o3lo+VkrQ5v8nTzMSy14zswQ= =FM5C -----END PGP SIGNATURE----- --oyz6roa7m34yy3ab--