The Service Access Facility (SAF) is used to control access to specific services on the machine. The main SAF program is the Service Access Controller (/usr/lib/saf/sac), which is responsible for managing the overall process, including spawning the individual daemons known as “port monitors.”
These, as their name suggests, are programs that monitor a port for incoming connection requests. Currently, two of these are supplied as standard, although the SAF can be extended to allow it to support custom monitors that have been written for specific applications. The supplied ones are listed here:
ttymon (this monitors the serial ports)
listen (this monitors the network ports)
Each port monitor needs to be “added” ...