ddfa man page on HP-UX

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ddfa(7)								       ddfa(7)

       ddfa  -	Data  Communications and Terminal Controller (DTC) Device File
       Access (DDFA) software

       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  structures.
       DDFA  provides  an  interface  to  remote LAN-connected terminal server
       ports that is similar to the  interface	for  local  directly-connected

       The  basic  principle  is  that a daemon is created for each configured
       terminal server port based on information in a  configuration  file  (a
       Dedicated Ports file).  When the daemon is spawned, it takes a from the
       pool and creates a device file with the same major and minor number  as
       the  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 and The daemon listens on
       the until an application does an on the pseudonym.  It then sets up and
       manages	the  connection to the terminal server port until the applica‐
       tion does a 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:

	      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 file is parsed by the Dedicated  Port	Parser
			     which  spawns  an	Outbound Connection Daemon for
			     each outbound connection specified in  the	 file.
			     The  file is also used by the HP-UX Telnet daemon
			     to identify incoming connections from a  DTC  and
			     map  them to a pseudonym (the Telnet port identi‐
			     fication feature).

	      Port Configuration File.
			     This text file is used by	DDFA  to  profile  the
			     terminal  server  port.   The generic name of the
			     template file is A	 port  configuration  file  is
			     referenced	 by  an	 entry	in the Dedicated Ports

	      Dedicated Port Parser.
			     This command parses the Dedicated Ports file  and
			     spawns  an	 Outbound  Connection  Daemon for each
			     valid entry in the file.  It can be run from  the
			     shell  or it can be included in a system initial‐
			     ization script  to	 automatically	run  the  DDFA
			     software each time the system is booted.

	      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 (but it  can  be  run  directly  from  the

			     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, will terminate  with
			     an error condition.

	      Outbound Connection Daemon debug mode.
			     This is a special version of that contains debug‐
			     ging code.	 It must be run from the shell.

       There are two basic steps to configuring the DDFA software:

	 ·  Enter information in the file.

	 ·  Enter information in the port configuration files.

   Configuring the dp File
       The file contains one line for each outbound connection that is	to  be
       established  and	 one  line  for	 each  incoming connection request.  A
       default file should be copied to a new file  and	 the  copy  edited  as
       needed.	It is recommended that a directory be created to hold the file
       and the port configuration files.

       Each line of the file must contain the location of the terminal	server
       port  and  the location of the pseudonym.  In addition, for an outbound
       connection, the port configuration file must be specified and a logging
       level may be specified.

   Configuring the Port Configuration Files
       A  port	configuration  file  is	 used to configure individual terminal
       server ports.  A master port configuration file is In practice,	it  is
       renamed for each port that needs different configuration values and the
       values are altered appropriately for the device attached to  the	 port.
       It is recommended that a directory be created to hold the port configu‐
       ration files and the file.

       Each line of a port configuration file must consist  of	a  name	 of  a
       variable	 and  its value.  The variable-value pairs contain information
       on how to open a connection to a terminal server port, how to  close  a
       connection to a terminal server port, and how to manage the data trans‐
       fer to a terminal server port.

   Configuring a System Initialization Script
       DDFA can be run at boot time by including a reference to	 in  a	system
       initialization  script.	It is recommended that the option be used when
       running in this environment.

       Note that should be killed using Do not use for this purpose as it does
       not remove the device file.  verifies the validity of an existing pseu‐
       donym before trying to use it.  and use data stored in the file to ver‐
       ify whether a process still owns a pseudonym before taking it over.  If
       finds an unowned pseudonym, it uses it.

       When receives a serious error condition, such  as  when	the  LAN  goes
       down,  it  transmits  the error condition to the application by closing
       the Any or to the pseudonym returns the error condition If the  pseudo‐
       nym  is the controlling terminal for the group to which the application
       belongs, is sent to all the  processes  in  the	group,	including  the

       Not  all functionality is available, due to the lack of a protocol that
       allows the transmission of such commands over the  LAN  to  the	remote

   termio Attribute Limitations
       The  main restrictions on attributes (see termio(7)) include modem sig‐
       nal control and parity checking.	 The following are not available:

   ioctl() Request Limitations
       The following request limitations apply:

	      DTC only supports one stop bit.

	      DTC only supports 8 bits per character.
				  Value cannot be modified.

	      DTC offers static configuration to handle even or odd parity.
				  It also handles auto	parity	detection  for
				  even or odd parity.

	      Enabling/disabling done via static configuration.
				  No programmatic interface supplied.

	      No way to separate input from output parity features.

	      Cannot be configured on DTC.

	      Bad characters are forwarded to the system without marking them
				  with OFFH or OH.

	      Speed is part of static configuration.

	      Flow control is enabled if the DTC static configuration
				  specifies  an	 ASCII access mode.  If binary
				  is selected, no flow control is provided.

	      Pacing of output to a terminal via a programmatic interface
				  is enabled when ASCII mode  is  selected  in
				  static  port configuration and disabled when
				  binary mode is selected.

	      DTC does not offer the ability to restart output
				  on any character received if XOFF was previ‐
				  ously received.

	      DDFA does not support the hanging up of modem signals
				  on  the  last	 close of the device file.  If
				  the modem signals used on the DTC drop,  the
				  connection is closed.

	      Not supported.

	      not supported.

				  not  supported by Telnet port identification

	      Part of static configuration is done in DTC Manager by selecting
	      binary mode.
				  If  switching	 is  enabled,  binary  can  be
				  selected at user interface level.  There  is
				  no  way  to  automatically  negotiate binary
				  mode when proper termio flags are reset when
				  using	 Binary/ASCII  switching  is  possible
				  with DDFA.  The  DTC	cannot	support	 large
				  reads	 in  pure  binary mode, so transferred
				  blocks of data should not be more  than  256
				  bytes.   If half-duplex with remote acknowl‐
				  edgement is implemented, binary applications
				  can be supported.

   ioctl() System Call Requests
       The following system call limitations apply:

	      The ability to send a break
				  without waiting for previous data to be sent
				  is not provided at the system	 level	in  or
				  DDFA.	  Receiving  a Telnet break command in
				  the DTC allows it to	generate  a  break  on
				  asynchronous ports.

	      The DTC output queue cannot be flushed.

	      Hardware handshake request
				  Not supported on DTC.

	      Local handshake cannot be disabled on DTC.

	      Not supported.

	      There is no way to separately set modem lines of a DTC port.

	      Modem  timers, CD timer, connect timer, and disconnect cannot be

	      CCITT simple, and direct call-in/call-out modes
				  DTC cannot handle simple mode because	 there
				  is programmatic interface for modem signals.
				  Call-in mode cannot be simulated if the port
				  is  opened,  because	modem  signals (or the
				  call) must be present within	2  minutes  or
				  the connection is cleared.

	      No way to get device adapter information.

	      No programmatic call to download the DTC.

	      No programmatic interface to get such info.

	      In  order	 to ensure that commands (such as ps) display the cor‐
	      rect device file name (that is, the pseudonym),  all  pseudonyms
	      should be placed into the directory If pseudonyms are not speci‐
	      fied for placement in this directory,  the  correct  display  of
	      device file names with many commands is not guaranteed.

       In  addition,  in  order to ensure that commands (such as and work cor‐
       rectly, each pseudonym must  be	unique	in  its	 first	17  characters
       (including  the	directory prefix If pseudonyms are not unique in their
       first 17 characters, the correct functioning of many  commands  is  not

       Also,  in order to reliably handle timing mark negotiations (and ensure
       that files printing on a printer attached to  a	terminal  server  have
       been  completely	 flushed  to that printer), the following line must be
       added near the end  of  each  printer  interface	 script	 for  printers
       attached to a terminal server:

       The  printer interface scripts reside in the directory The line must be
       added just prior to the final command in each printer interface script.

       If this line is not added as specified,	the  printing  reliability  of
       printers attached to a terminal server is not guaranteed.

       dpp(1M),	 ocd(1M),  ocdebug(1M),	 ioctl(2),  dp(4),  pcf(4),  ioctl(5),


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