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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 1/27/26 21:55, Patrick M. Hausen wrote: > HI all, > > Am 27.01.2026 um 21:46 schrieb Marek Zarychta : > >> To narrow the impact, I suggest switching to the MAC address as the default key source instead of the interface name. > > If I read the relevant RFC correctly the main argument for stable addresses in contrast to > traditional EUI-64 is the narrowing of the search space in sweep scan attacks. > Because the OUIs which make up half of the order of magnitude are well known. > > Isn't that the case, too, if we start with the MAC address and the hash algorithm > by which the final address is generated is public? > All this has already been discussed in the code review. My intent while implementing this was to adhere to the RFC letter and intent. Looks like some suggestions are based on the idea that personal preference has priority over RFC conformance. The RFC has a relatively strict description of the algorithm. Anyway the point against using MAC addresses, and preferring other options, is clearly stated in the RFC in appendix A. The MAC address is suggested as a third option (the first was not really viable in FreeBSD since interface indexes are not stable, so I used the second as the main one), and the paragraph talking about MAC addresses clearly states it is not a good choice [1]. I'd also add that my understanding of the RFC is that the compromise between privacy and address stableness in this one is more towards stableness of the address, which is also what I was after. There are other more recent RFCs addressing the privacy issues more aggressively (for example RFC 8981). If privacy is the primary concern these options should be investigated. I don't see how cloned hosts should be a problem. it is quite easy to force a machine to regenerate its hostid. Anyway I will not scream against changing the default for sysctl net.inet6.ip6.stableaddr_netifsource, but my opinion is against changing it, for all the reasons I have already stated in the review and here, and will not perform such a change myself. [1] https://www.rfc-editor.org/rfc/rfc7217#appendix-A.3 -- Guido Falsi