Am 09.07.21 um 00:20 schrieb Steven Champeon via mailop: > on Thu, Jul 08, 2021 at 02:28:13PM -0700, Michael Peddemors via mailop wrote: >> Ex. 1.186.104.104 x1 1.186.104.104.dvois.com > Even better still dvois.com uses the same naming for dynamics and > statics. At least they only have the couple - though they also use > static.dvois.com right anchored PTR naming, they don't ALWAYS, so it's a > risk to just assume. I've dealt with Indian ISPs with hundreds, if not > thousands of naming "conventions". The old vsnl and bsnl were awful. > >> Time to brush off M3AAWG best practices.. listing what ports do not >> need to be open on dynamic IP home style networks.. > That's just it - you can't assume dynamic with dvois.com, and many more. > I have at least 136 patterns that I had to throw my hands up and call > "mixed" because they either lie, don't distinguish, or are so > incompetent they can't be bothered to not hand out statics with 'dyn' > token labels, and vice versa (eg., rima-tde). Much of Brazil is simply > generic, stuff like 1-2-3-4.example.net.br. We tend to assume generic == > dynamic, especially when they've got tiny allocations, but shrug. > > Steve > IMHP that's the wrong approach. The question isn't whether IP addresses are dynamically or statically assigned, but whether it is possible with reasonable effort to find an entity that is responsible for SMTP traffic coming from an IP address. It doesn't matter whether the IP address has no pointer, has "dynamicip" or "staticip" or one of the various anonymous cloud hosting domain names in it.
You might want to make individual exceptions for IPs that you know are associated with fixed domains (for example, when SPF records indicate that the IP is being used by that domain and you trust the domain itself), but as a general rule, clients accessing port 25 should have non-generic PTR entries. Cheers, Hans-Martin _______________________________________________ mailop mailing list [email protected] https://list.mailop.org/listinfo/mailop
