[core] server.v4mapped option
[core] server.v4mapped option

For IPv6 listen addresses:
server.v4mapped = "disable" results in IPV6_V6ONLY socket opt set to 0
server.v4mapped = "enable"  results in IPV6_V6ONLY socket opt set to 1

server.v4mapped has an effect only if explicitly set in lighttpd.conf.
If not set, the socket option is inherited from kernel defaults, which
may vary on different OS.

server.v4mapped takes priority over server.set_v6only

server.set_v6only behavior is inconsistent and depreacted.
server.set_v6only behavior differs from server.v4mapped in that
server.set_v6only = "enable" will cause the IPV6_V6ONLY socket
option to be set to 1 for IPv6 listening sockets configured via
$SERVER["socket"] in lighttpd.conf, is enabled by default, and
has no effect if set to "disable"

Note: IPv4-mapped addresses may bring potential security issues,
depending on the situation.  For example, lighttpd does not attempt
to match IPv4 addresses with IPv4-mapped addresses.  Other writings:
https://tools.ietf.org/html/draft-itojun-v6ops-v4mapped-harmful-02.html

lighttpd/lighttpd1.4,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,lighttpd/lighttpd1.4,gstrauss/lighttpd1.4,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,gstrauss/lighttpd1.4