Mihal Iacob and Walid Rhaibi have just published "Restricting database connections using the CONNECT_PROC database configuration parameter in DB2 for Linux, Unix, and Windows"
From the article summary:
System administrators are responsible for, among other things, protecting a database against unauthorized access or misuse by authorized database users (for example, inappropriate access to sensitive information within a database). A common requirement to mitigate such risks is ensuring that users are allowed to connect to the database only from a list of trusted hosts or IP addresses that are known to be secure. This article gives a practical example of how such a requirement can be put in practice by making use of the CONNECT_PROC database configuration parameter of IBM® DB2® for Linux®, UNIX®, and Windows®.