Adding more support for graceful IPv6 detection

[minusdavid]

I've noticed that programs in Docker are running with 2.009 are ok without an explicit host in a port specification, but with 2.013 we're getting fatal errors.

Resolved [*]:8023 to [::]:8023, IPv6
Not including resolved host [0.0.0.0] IPv4 because it will be handled by [::] IPv6
Binding to TCP port 6001 on host 127.0.0.1 with IPv4
Binding to TCP port 8023 on host :: with IPv6
2024/05/24-01:00:23 Can't connect to TCP port 8023 on :: [Invalid argument]
at line 66 in file /usr/share/perl5/Net/Server/Proto/TCP.pm

I do see at https://metacpan.org/pod/Net::Server#ipv-(IPv4-and-IPv6) that you've provided lots of ways of enabling/disabling different versions. That's awesome.

I was wondering what you think about checking the system setting "net.ipv6.conf.all.disable_ipv6" as well. Out of the box, it seems all Docker systems have this set.

I imagine consulting the other "disable_ipv6" settings would be difficult since they're more interface specific. But curious what your thoughts on that might be.

Anyway, we're all sorted now, but thought I'd pass on our experience.