MariaDB MaxScale 2.1 defaulting to IPv6

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Mattias Geniar, June 20, 2017

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This little upgrade caught me by surprise. In a MaxScale 2.0 to 2.1 upgrade, MaxScale changes the default bind address from IPv4 to IPv6. It’s mentioned in the release notes as this;

MaxScale 2.1.2 added support for IPv6 addresses. The default interface that listeners bind to was changed from the IPv4 address to the IPv6 address ::. To bind to the old IPv4 address, add address= to the listener definition.

Upgrading MariaDB MaxScale from 2.0 to 2.1

The result is pretty significant though, because authentication in MySQL is often host or IP based, with permissions being granted like this.

$ SET PASSWORD FOR 'xxx'@'' = PASSWORD('your_password');

Notice the explicit use of IP address there.

Now, after a MariaDB 2.1 upgrade, it’ll default to an IPv6 address for authentication, which gives you the following error message;

$ mysql -h127.0.0.1 -P 3306 -uxxx -pyour_password
ERROR 1045 (28000): Access denied for user 'xxx'@'::ffff:' (using password: YES)

Notice how turned into ::ffff: That’s an IPv4 address being encapsulated in an IPv6 address. And it’ll cause MySQL authentication to potentially fail, depending on how you assigned your users & permissions.

To fix, you can either;

  • Downgrade MaxScale from 2.1 back to 2.0 (add the 2.0.6 repositories for your OS and downgrade MaxScale)
  • Add the address= config the your listener configuration in /etc/maxscale.cnf

In case of your MaxScale listeners, this should be enough to resolve the problem.

$ cat maxscale.cnf

Hope this helps!

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