HP-UX Reference (11i v3 07/02) - 7 Device (Special) Files, 9 General Information, Index (vol 10)

d
ddfa(7) ddfa(7)
NAME
ddfa - Data Communications and Terminal Controller (DTC) Device File Access (DDFA) software
DESCRIPTION
The Data Communications and Terminal Controller (DTC) Device File Access (DDFA) software allows
access from HP-UX system utilities and user applications to terminal servers using standard HP-UX struc-
tures. DDFA provides an interface to remote LAN-connected terminal server ports that is similar to the
interface for local directly-connected ports.
The basic principle is that a daemon is created for each configured terminal server port based on informa-
tion in a configuration file (a Dedicated Ports file). When the daemon is spawned, it takes a
pty from the
pool and creates a device file with the same major and minor number as the
pty slave. The device file is
known as the "pseudonym" and utilities and applications use the pseudonym to access the terminal server
port by exercising standard HP-UX system functions (
open(), close(), read(), write(), and
ioctl()). The daemon listens on the pty
until an application does an open() on the pseudonym. It
then sets up and manages the connection to the terminal server port until the application does a
close()
on the pseudonym. The end result is that the terminal server port is addressed via a device file, but the
mechanism that makes it happen is transparent to the user. A second configuration file (a port
configuration file) contains information to profile the terminal server port.
DDFA consists of the following items:
dp Dedicated Ports file. This text file contains the information that DDFA needs to set
up and manage a connection between a pseudonym and a terminal server port.
The dp file is parsed by the Dedicated Port Parser (
dpp) which spawns an Outbound
Connection Daemon (
ocd) for each outbound connection specified in the file. The
dp
file is also used by the HP-UX Telnet daemon (telnetd
) to identify incoming connec-
tions from a DTC and map them to a pseudonym (the Telnet port identification
feature).
pcf Port Configuration File. This text file is used by DDFA to profile the terminal server
port. The generic name of the template file is
pcf. A port configuration file is refer-
enced by an entry in the Dedicated Ports file (dp).
dpp Dedicated Port Parser. This command parses the Dedicated Ports file (
dp) and
spawns an Outbound Connection Daemon (
ocd) for each valid entry in the dp file. It
can be run from the shell or it can be included in a system initialization script to
automatically run the DDFA software each time the system is booted.
ocd Outbound Connection Daemon. This daemon manages the connection and data
transfer to the remote terminal server port. Normally, it is spawned by the Dedicated
Ports Parser (
dpp), but it can be run directly from the shell.
As it starts, it creates its pseudonym for the connection. As it terminates normally, it
removes the pseudonym. If the pseudonym is removed while it is running, ocd will
terminate with an error condition.
ocdebug Outbound Connection Daemon debug mode. This is a special version of ocd that con-
tains debugging code. It must be run from the shell.
CONFIGURATION
There are two basic steps to configuring the DDFA software:
• Enter information in the dp file.
• Enter information in the port configuration files.
Configuring the dp File
The dp file contains one line for each outbound connection that is to be established and one line for each
incoming connection request. A default file /usr/examples/ddfa/dp should be copied to a new file
and the copy edited as needed. It is recommended that a directory be created to hold the
dp file and the
port configuration files.
Each line of the dp file must contain the location of the terminal server port and the location of the pseu-
donym. In addition, for an outbound connection, the port configuration file must be specified and a logging
level may be specified.
32 Hewlett-Packard Company − 1 − HP-UX 11i Version 3: February 2007