On 8.3.2010, at 2.22, Wietse Venema wrote: >> Of course I fixed the problem immediately as I found out about >> it, but I'm just wondering how many other such setups there are >> that break once IPv6 becomes more common. Should this setting >> default to "any"? Is there really even a reason for it to be other >> than "any" (at least until IPv6 really is commonly used everywhere)? > > Perhaps, that's why I talked about "smtp_address_preference = any" > on the mailing list.
Yeah, just trying to give some example. > Currently, Postfix ships with "inet_protocols = ipv4" as the default, > so people who turn on IPv6 support should know what they are doing. And when I changed it, I did know what I was doing. But a few years later I forgot about it. When switching ISP, it was obvious that I had to change my IP addresses, so I changed them in all my configs. But it was much less obvious that I had to change anything else, like remember that I had enabled IPv6 in some application that could sometimes break because of that change. That brings another thought to my mind: Maybe the default could be based on current DNS settings? If the server's primary address has IPv6 DNS record, prefer it, otherwise prefer any. (I haven't thought much yet if it's that good of an idea.) > I don't know common it is to have different performance levels or > different failure modes for IPv6 and IPv4. Nor do I know how common > it is for destinations to have half a dozen or more IPv6 addresses > (i.e. more than the default Postfix smtp_mx_address_limit of 5). Me neither. And it was fine for many years. But maybe it's soon getting worse as IPv4 address availability is disappearing.
