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CHAPTER 7: UNIX/RTEL Host Setup
7. UNIX/RTEL Host Setup
This chapter explains how to set up your UNIX host to take advantage of
the Reverse Telnet software. Reverse Telnet allows your UNIX host to form
connections to the EPS, through the host’s print queueing system, a device
interface, or with applications such as Telnet and Rlogin. Read through the
entire installation procedure before beginning. You must have the EPS in
your system’s host table to use the RTEL features. The table is usually a file
called “/etc/hosts” that should contain the name and IP address for your
server, as well as all the hosts on your network. For example, to add server
eps1 at IP address 192.67.8.22, include this line in your /etc/hosts file:
192.67.8.22 eps1
One of the most common causes of IP network problems is duplicate IP
addresses. Make sure that your EPS has a unique IP address.
7.1 Reverse Telnet Background
The RTEL software provides the ability to form connections from UNIX hosts
to EPS server. You can create these connections either through a backend for
the hosts’ lp or lpr printing, or as a device file that any application can access.
Queueing can be enabled so that connections to a busy service are queued for
later processing. RTEL jobs can also be interspersed with LAT connections to
the same service.
There are two methods of connecting between the UNIX host and the EPS.
1. You can link the RTEL software to your host’s printing system, so that
jobs queued for printing can be sent to a printer on the EPS for
processing. This path provides options to support PostScript output,
plotter (and other non-ASCII data) files, and automatic banner page
generation and tab expansion.
2. You can use a pseudo-tty device file (such as /dev/ttyp1) on the UNIX
host which is mapped to the RTEL software. Any user or application
using that device can be connected to an EPS service. For example, if a
word processor is told that a printer is on device /dev/ttyp1 and that
device is connected to an EPS via RTEL, output from the word processor
will be sent to the EPS automatically. Communications programs, such as
Kermit, can also benefit. If an EPS is offering a modem service, users on
the UNIX host can access that modem via RTEL without having the
modem directly attached to their host. Since the device interface is just a
“pipe” through which data is transferred from a host to an EPS, it does