Just 1 problem: some ISPs are giving /56 to users. And even bigger problem: 37% of ISPs replace /56 for every subscriber reconnect. One end up on filtering IPv6 /32 very fast. Ed/ -----Original Message----- From: Lyndon Nerenberg (VE7TFX/VE6BBM) <lyndon@xxxxxxxxxx> Sent: Monday, July 1, 2024 21:11 To: Phillip Hallam-Baker <phill@xxxxxxxxxxxxxxx> Cc: Keith Moore <moore@xxxxxxxxxxxxxxxxxxxx>; ietf@xxxxxxxx Subject: Re: No, SMTP is IPv4, Was: SMTP and IPv6 Phillip Hallam-Baker writes: > I don't see that happening for SMTP because the big cost of managing > SMTP services is the anti-abuse system, in fact that is pretty much > the only cost. And going from 32 bits to 128 bits (or 64 if you want > to look at it that way) is simply too much leverage to hand over to the attackers. I'm not sure that's entirely true. ip6 means a near infinite number of addresses per host, but almost always those come out of a local /64 LAN. So instead of doing reputation on ip4 /32s, you do it on ip6 /64s. The addresses get longer, but the number of entries you track is going to be similar. It would be ineresting to examine the "worst 10%" of a few ESP's ip6 bad reputation lists to see if this sort of clustering happens in reality. --lyndon
