You will need to configure PAM on your system for how it should authenticate for MySQL. A simple setup can be to use the standard UNIX authentication method.
NOTE: Using pam_unix means the MySQL Server needs to read the /etc/shadow file, which usually means it has to be run as root - usually not a recommended configuration.
A sample /etc/pam.d/mysqld file:
auth required pam_unix.so account required pam_unix.so
For added information in the system log, you can expand it to be:
auth required pam_warn.so auth required pam_unix.so audit account required pam_unix.so audit
You will need to execute CREATE USER with specifying the PAM plugin. For example:
CREATE USER 'username'@'host' IDENTIFIED WITH auth_pam;
This creates a user username that can connect from host and will be authenticated using the PAM plugin. If you are using the pam_unix method in PAM (or similar) you will need to have an account for username existing on the system.
Percona Server has implemented PAM plugin support for supplementary groups. Supplementary or secondary groups are extra groups a specific user is member of. For example user joe might be a member of groups: joe (his primary group) and secondary groups developers and dba. A complete list of groups and users belonging to them can be checked with cat /etc/group command.
This feature enables using secondary groups in the mapping part of the authentication string, like “mysql, developers=joe, dba=mark”. Previously only primary groups could have been specified there. If user is a member of both developers and dba, PAM plugin will map it to the joe because developers matches first.