MySQL 9.1 Release Notes
The MySQL server listens on one or more network sockets for TCP/IP connections. Each socket is bound to one address, but it is possible for an address to map onto multiple network interfaces.
Set the bind_address system
variable at server startup to specify the TCP/IP connections
that a server instance accepts. You can specify multiple values
for this option, including any combination of IPv6 addresses,
IPv4 addresses, and host names that resolve to IPv6 or IPv4
addresses. Alternatively, you can specify one of the wildcard
address formats that permit listening on multiple network
interfaces. A value of *, which is the default, or a value of
::, permit both IPv4 and IPv6 connections on
all server host IPv4 and IPv6 interfaces. For more information,
see the bind_address
description in Section 7.1.8, “Server System Variables”.