HP 9000 Manual page 16

How DDFA Utilities
Work
2-2 Overview of DDFA And Telnet Port Identification
DDFA allows user applications to access devices
attached to DTC and other terminal servers
using standard HP-UX system calls.
Telnet Port Identi cation lets the system
administrator ensure that incoming Telnet connections
from speci c DTC ports will be assigned to speci c,
rather than random pty device les.
read write open close ioctl
cannot