RFC 8555 section 8.3 [1] states HTTP challenge MUST be served over TCP
port 80 and while the verification follows redirects, those are unneed
and migh be harmful in specific deployment scenarios.
[1] https://datatracker.ietf.org/doc/html/rfc8555#section-8.3
Signed-off-by: Wojtek Porczyk <woju@invisiblethingslab.com>
nginx only binds an IPv4 socket, if the listen option is specified
without [::]. There are two possibilites to fix this issue.
Either the listen option can be specified using only [::], and
additionally including ipv6only=off. This makes nginx bind an IPv6
socket which is also able to handle IPv4 connections.
Or the listen option can be specified twice, one with [::] and one
without. This makes nginx bind two independent sockets.
If the first option is chosen, IPv4 addresses are mapped into the IPv6
address space, which might break scripts, filters, etc.
So, for now, the second option is chosen.