Fwd: DOvecot requires both IPv4 and IPV6 to start
Damn. Forgot to hit "reply all" -- my bad
-------- Forwarded Message -------- Subject: Re: DOvecot requires both IPv4 and IPV6 to start Date: Mon, 4 Sep 2023 15:35:51 -0700 From: Stephen Satchell list@satchell.net Reply-To: list@satchell.net To: Arjen de Korte build+dovecot@de-korte.org
On 9/4/23 2:40 PM, Arjen de Korte wrote:
This document was written something like two decades ago and pretty much all arguments against IPv6 are no longer relevant anymore. In most cases nowadays, the user experience for IPv6 will be far superior over CGNAT connections which unfortunately become the standard due to the increasing cost of IPv4 addresses. Running services over IPv6 may have been experimental and prone with not so fun problems to diagnose in 2013, but today this is no longer the case.
Running a business? Subscribing to business Internet? Are IPv6 address blocks available? Does IPv6 routing work properly?
OK, even though the service desk doesn't know how to answer the above questions about IPv6 correctly, the information *is* available if you dig hard enough. And it seems to work.
Can you get a PTR6 record for your mail server?
No. At least, not from my upstream. Begins with "A" and ends with "T". Don't even ask about reverse delegations, the blank stare will scare you.
(I apologize to everyone on this list. The above diatribe more correctly lives on mailing lists for Sendmail, Postfix, Exim, and other packages that actually originate mail exchanges.)
- Stephen Satchell:
Running a business? Subscribing to business Internet? Are IPv6 address blocks available? Does IPv6 routing work properly?
Yes, to all of the above. For several years, I have been using various IPv6-only servers for my business. For some, like my MX, I still prefer to use both IPv4 and IPv6 simultaneously, so as not to exclude the less fortunate users still lacking IPv6, but other servers do just fine with IPv6 only.
My servers are hosted in data centers across Europe, with native IPv6 capability, and each machine is assigned a cost-free /64 subnet. Finding a suitable ISP is of course a prerequisite. My home office Internet connection is handled by a different ISP, but also one which supports native IPv6. Before they did, I used SixXS (https://www.sixxs.net/) from home. As for devices: iOS and macOS actually prefer IPv6 over IPv4 if both are available, if this matters to you in any way. Linux obviously won't break a sweat, and neither will Windows.
Routing is a breeze, as per usual with IPv6, and I can freely divide my servers' /64 subnets further. I use this for separate /96 subnets for LXD, Docker and the like. Easy as pie, no more port clashes for different services, no outrageous payments for additional IPv4 addresses now that the pool has been exhausted.
I don't mean to preach, and I am aware that the availability of native IPv6 varies widely. What I recommend is this: If you can, try your hand at using IPv6 on a smaller scale to get your head around it. Concepts and terminilogy may look confusing at first, but the design is actually more coherent than IPv4 (speaking as a computer scientist here). I think you will come to like features like Stateless Address Autoconfiguration (SLAAC) and Neighbor Discovery Protocol (NDP). No more DHCP needed. To then connect to the wider world, even a Raspberry Pi, easily configured with Router Advertisement (RA), can suffice. Just try it, what is there to lose?
-Ralph
participants (2)
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Ralph Seichter
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Stephen Satchell