The address you specify in bind tells MySQL where to listen. 0.0.0.0 is a special address, which means "bind to every available network".
Only client software which is able to open a connection to the server using the same address that is specified in the 'bind' option will be allowed to connect.
Some examples:
- If MySQL binds to 127.0.0.1, then
only software on the same computer
will be able to connect (because
127.0.0.1 is always the local computer).
- If MySQL binds to
192.168.0.2 (and the server computer's IP address is
192.168.0.2 and it's on a /24 subnet), then any computers on the same
subnet (anything that starts with 192.168.0) will be able to connect.
- If MySQL binds to
0.0.0.0, then any computer which is able to reach the server computer
over the network will be able to connect.
These are all transport-level connections. Remote computers still need to qualify for application-level, which is to say they will still require the correct login credentials and host parameters from mysql.user.
