MySQL远程连接的rDNS安全

Question

Consider a MySQL server that accepts remote connections.

What happens if you have a publicly facing MySQL server, and grant access to eg: 'sqluser'@'localhost'

If an attacker now sets his rDNS to "localhost", will he able to access this database?
Is there an extra check that also tries to resolve the rDNS back to the IP?

Regardless, database servers shouldn't be internet facing, but this a what-if-question.

Answer 1

It appears that MySQL uses forward-confirmed reverse DNS (FCrDNS) to counter these kind of attacks.

Most of the logic for the hostname checks can be found in sql/hostname.cc . Moreover, several checks are also performed to make sure that the rDNS doesn't contain an IP or is otherwise poisoned .