HP-UX AAA Server A.08.02 Administrator's Guide

26 Customizing the HP-UX AAA Server Using the Finite State
Machine
The main component of the server’s software engine is the Finite State Machine (FSM) and a few
associated routines. At server startup, the FSM reads instructions from a state table by loading
and parsing a .fsm file. By default, it loads the radius.fsm file, unless it is missing or if you
have specified another .fsm file using the radiusd -f command. The .fsm file defines a state
table that includes the states, events, and actions that determine how a request is processed.
You can track different versions of state tables by adding the following line to the .fsm file:
%FSMID Version-String
Version-String is the version information. This string will appear in radcheck output.
States
In the Finite State Machine, a request will transition through a series of states, beginning with a
state that includes possible starting events. The action specified to be called first in response to an
initial authentication request will return a value, an event that determines the next state to transition
to. Within each state, the next action is triggered by an event (based on previous state and action
and a value, typically ACK or NAK, returned by the previous action), which in turn directs the flow
of the request to another state, until an End state is reached. Figure 92 shows at a high level the
process that occurs, as the result of a request, in the finite state machine.
Figure 92 Default FSM State Transitions
The actions triggered during this process read information from the server’s configuration, and
from stored user profiles, and policy. Based on this information the actions perform the server’s
authentication, authorization, and accounting functions.
290 Customizing the HP-UX AAA Server Using the Finite State Machine