In DB2, user and group authentication is performed by a facility that is external to the DB2 database management system, such as the operating system, a domain controller, or a Kerberos security system. It is accomplished using dynamically loadable libraries called security plug-ins.
The default IBM DB2 username/password plug-in authenticates users only in an NIS domain or in the
/etc/passwd password file. If another security plug-in has not been explicitly configured, the user credentials provided in the connection request are authenticated by the security facility on the DB2 Universal Database (UDB) server. That is, the default plug-in sends the user ID and password to the operating system for validation.
Authorization is the process of determining access information about specific database objects and actions based on a supplied user ID. Privileges can be granted to specific users or to groups of users. Users that are a member of a group automatically inherit the group’s privileges. As mentioned before, these users and groups are defined outside the DB2 UDB; for example, in Active Directory.
DB2 supports replacement plug-ins for authentication and authorization. The authentication plug-ins can replace the default user name and password method, and support alternative authentication methods including GSSAPI. DB2 also supports the use of multiple plug-ins for authentication.