ipv 4 and 6

[Maxim Dounin]

Hello!

On Wed, Jul 29, 2026 at 11:40:39AM -0400, Paul wrote:

> nginx/1.18.0 (Ubuntu).   For decades we have never explicitly "listened" for
> 1pv6, using only "listen 443 ssl;" on a couple of dozen websites.
> 
> As of two days ago, W3C (world wide web consortium) html, css, etc
> verification tools are no longer functional -- our websites "time out" "500
> Can't connect to mysite.com:443 (Connection timed out)"
> 
> W3C have nslookup showing ipv4 and ipv6 addresses.  There is nothing in our
> firewalls "denying" them, there is nothing in the nginx logs.
> 
> I'm reticent to just add trillions of ipv6 possibilities of abuse (we're
> experiencing om/off ddos attacks from ai/automated/bots to the tune of
> 56^6/day).
> 
> Any thoughts?

So, your website names resolves to both IPv4 and IPv6 addresses, 
but you don't have any IPv6 listens, correct?

This looks like a configuration error to me, and the fact that W3C 
tools fail isn't surprising.  There are two obvious solutions: 
either add relevant IPv6 listen directives, or remove the IPv6 
addresses from the website names.

-- 
Maxim Dounin
http://mdounin.ru/