# MIT Kerberos Documentation

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# Internal pluggable interfaces

Following are brief discussions of pluggable interfaces which have not yet been made public. These interfaces are functional, but the interfaces are likely to change in incompatible ways from release to release. In some cases, it may be necessary to copy header files from the krb5 source tree to use an internal interface. Use these with care, and expect to need to update your modules for each new release of MIT krb5.

## Kerberos database interface (KDB)

A KDB module implements a database back end for KDC principal and policy information, and can also control many aspects of KDC behavior. For a full description of the interface, see the header file `<kdb.h>`.

The KDB pluggable interface is often referred to as the DAL (Database Access Layer).

## Authorization data interface (authdata)

The authdata interface allows a module to provide (from the KDC) or consume (in application servers) authorization data of types beyond those handled by the core MIT krb5 code base. The interface is defined in the header file `<krb5/authdata_plugin.h>`, which is not installed by the build.