4 ms·
It’s customarily used for e-mail transport.
by teddyh 2y ago
It’s customarily used for e-mail transport.
- tptacek 2y agoNo, it isn't; it can't be, because none of the major email domains are DNSSEC-signed to begin with. Let me know if I've misunderstood your point, and there some other widespread niche usage DANE finds in SMTP.
- teddyh 2y ago“Customarily” must not necessarily mean “major email domains”. As I understand it, DANE is commonly used by organizations wanting to secure e-mail between them; DANE enforcement is agreed by both parties, and then used without issue.
- wolf550e 2y agoDidn't they invent MTA-STS so they could not use DANE? They use MTA-STS.
- teddyh 2y agoI know that is what MTA-STS is for, but haven’t heard from people actually using it. I have, however, heard from people using DANE in the way i described. (For those who don’t know, MTA-STS is basically DANE but for people who hate DNSSEC. And are OK with requiring every mail server to also have a web server running.)
- tptacek 2y agoRespectfully, what are you talking about? The four largest email providers in the world all run STS. You can test for yourself: just do `dig +short txt _mta_sts.DOMAIN`. I stopped looking after I saw that even Yahoo Mail does it.
- teddyh 2y agoI’m talking about hearing from actual people running their own e-mail infrastructure, or who are at least working closely with some local party to run it for them. What the humongous e-mail providers do is largely irrelevant for the purposes of what people in general should do with their own systems; what large providers do is rarely in the interests of anyone else but themselves. (Also, your test is wrong. It should be “_mta-sts”, not “_mta_sts”.)
- tptacek 2y agoWhat an odd definition of "using it". It only counts if just a couple random people set it up, but not if hundreds of millions of people rely on it.
- teddyh 2y agoYou frequently argue that DNSSEC usage only counts when it’s added to domains by the domain owners, not when it is added by DNS server operators (who are frequently also the registrars). Why then should MTA-STS usage count if it’s done by the few huge centralized e-mail providers? When it’s purposefully set up by actual people, I only hear about DANE. It’s only when talking about huge e-mail providers that I hear about MTA-STS. And, as I said previously, those huge providers probably chose MTA-STS not for any reason which benefits their regular users, but for reasons which benefits only themselves, being a huge operator.
- tptacek 2y agoNo! These aren't comparable problems. MTA-STS is designed to defeat SSL-stripping. It works whether specific users know about it or not. That is not the case for DNSSEC. This is why MTA-STS is overwhelmingly deployed across email users, and DNSSEC has less than 5% deployment (and falling). Thanks for the opportunity to clarify. If you're wondering why DNSSEC never took off, these kinds of exchanges are illustrative!
- 2y ago
- teddyh 2y ago(This use of DANE is explicitly described in RFC 7672, section 6.)