Configuring Reverse Telnet Service for Printers

7318 Model S20 Guide and Reference

Configuring Reverse Telnet Service for Printers

The 7318 listens for and carries out printer requests using its reverse telnet service, known internally as telnetd daemon. Setting up a printing device on a 7318 serial or parallel port or through a serial-attached terminal involves configuring an appropriate service on the 7318.

Note: When attaching a printer to the Model S20, configure the port as a P10-style port. Refer to "Adding a P10-Style Port" for a detailed procedure. The P10-style port takes advantage of the AIX spooler. Reverse telnet service can be used for printing but has limited functionality and is not recommended for AIX.

The [Telnetd] section lists how many additional Telnetd sections of the form [TelnetdNN] are found in the configuration.

ntelnetds=NN

Number of [TelnetdNN] sections follow.

The [TelnetdNN] section lists an association between the telnetd process and logical devices. Such associations are made only after a connection has been made to a particular telnetd port. Based on the ntelnetds entry in the [Telnetd] section, the configuration is expecting sections [Telnetd00] through [Telnetd(NN-1)].

device=String

Defines a 7318 logical device to which telnetd will attach when a connection is made. Acceptable values for the String parameter are:

COM	Specified for applications that have their own line protocols.
LPT	Specified for printer applications that have their own line protocols and parallel port printers.
TPRINT	Specified for a transparent-terminal printer.
LDTCOM	Specified for a terminal. Allows the use of stty commands to set port parameters.
LDTLPT	Specified for a printer.

Refer to the Legal Device Types table for more information on devices and sessions.

port=Integer	Defines a 7318 serial or parallel port to which telnetd will attach when a connection is made.
tcpPort=N	Defines the TCP port where N is a decimal number.

Following is an example configuring both a parallel and a serial printer:

[Telnetd]
ntelnetds=2
 
;Parallel Printer
 
[Telnetd00]
device=LPT
port=1
tcpPort=5101
 
;Serial Printer
 
[Telnetd01]
device=LDTCOM
port=3
tcpPort=5103

Note: When you enable the reverse telnet service on a port, you must disable other sessions such as the command shell for that port. Edit the configuration file and change the application entry for all numbered session sections for the port you plan to use to the value reserved.

One possible configuration assigns TCP ports in the range 5101 through 5116 for serial COM ports 0 through 15. Use TCP ports 5201 and 5202 for the two parallel ports. Use TCP ports 5301 through 5316 for terminal-attached printers on serial ports 0 through 15. These numbers are arbitrary and suggested for mnemonic convenience.

Prerequisites

You must have root authority.
You must copy the s20.cfg default configuration file to the 7318EthernetADDR.cfg file before making configuration changes.

Procedure

To enable the reverse telnet service on a serial port:

Use a text editor to modify the configuration file for your 7318.
Locate the [Telnetd] section and add one to the value of the ntelnetds entry.
Uncomment an existing numbered telnetd section or add a new section specifying the following parameters:
```
device=COM
port=n
tcpPort=m
```
where n is the number of the port and m is the value of the TCP port you have selected.
Locate all [SessionNN] sections that refer to the port you are configuring and change the value of the application entry to reserved.
For some types of printers and some types of host configuration you may also want to set an stty command for the printer session which is session 0 by default.
```
[Session08]
device=LDTCOM
port=2
session=0
application=reserved
stty=opost onlcr tab3
```
Save the file and exit the editor.
When all users have logged off the 7318, reboot it to reload the modified configuration file.

Related Information

Using Dial-Out Modems and Reverse Telnet.