LPRng-HOWTO: Introduction

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## 1. Introduction

This document is an attempt to provide some simple guidelines to set up LPRng. It is aimed at system managers who want to replace their vendor's printer daemon and its clients by LPRng.

LPRng can be configured in many ways, making it suitable for a broad range of applications. It has a large amount of options which are explained in the extensive documentation.

Despite (or due to) the extent of the documenting files, many new users experience problems in setting up the package. One of the reasons is that most of the LPRng documentation assumed that you already have a working knowledge of a BSD-style printer spooler.

In this document, I will first try to give some simple guidelines that should enable you to put together a simple working configuration without being overwhelmed by options. Next, there are some detailed descriptions of the way that LPRng does things. Finally, there are detailed discussions about various LPRng facilities that try to encapsulate common configurations and operations that administrators and users encounter.

## 1.1 What is LPRng?

Gordon Haverland (`haverlan@agric.gov.ab.ca`) put it this way:

> LPRng is a print spooling system. It was designed to mimic the Berkeley (University of California - Berkeley) Line Printers (LPR) package, first found on Berkeley derivatives of the Unix operating system. The LPRng package supports users being able to print a document with little or no knowledge of the content or special processing required to print the document; on a stand-alone machine, on a LAN, or remotely. New (as compared to Berkeley LPR) features include: lightweight `lpr`, `lpc` and `lprm` programs; dynamic redirection of print queues; automatic job holding; highly verbose diagnostics; multiple printers per queue; and enhanced security (SUID not required in most environments), improved file permissions, authorization checks, ...), etc.

Patrick Powell (`<papowell@astart.com>`), the author of LPRng, has the following comments:

> LPRng started life in 1986 as PLP (Public Line Printer), a replacement for the original BSD LPD code. This was a one-shot effort to develop code that could be freely redistributed without the restrictions of the BSD/AT&T license, and would allow non-license sites to fix and patch problems that they were having with print spooling. (This was before the Free Software Foundation.) From 1988 to 1992, various groups added features, hacked, and modified the PLP code, coordinated largely by Justin Mason (`<jmason@iona.ie>`), who also started and sponsors the LPRng mailing list (see below).

> In 1992, I redesigned and reimplemented the PLP code and named the result LPRng. The goals of the LPRng project were to build a server system that was as close to user abuse proof as possible, that would provide services limited only by the inherent capacities of the support system, RFC1179 compliant, and with extensive debugging capabilities to allow quick and easy diagnostics of problems. Over the period from 1994-1997, LPRng users have suggested extensions, provided patches, and added facilities. I have tried to incorporate these in a controlled and cautious manner.

> As a side effect of this work, many security problems that could develop were identified and steps taken to ensure that they were not present in LPRng. For example, if you want, you can run LPRng clients such as lpr, lprm, lpc, and lpq as a non-privileged user; this reduces the chances of users exploiting faults in the code and gaining root privileges. Bounds checking is performed on all input and formatting (for example, snprintf() rather than sprintf() is used), as well as other preventive measures where appropriate.

In most cases, LPRng is not a drop-in replacement for BSD LPR. For most installations, you will need adaptations. However, most of the changes are minor, and many of the LPRng facilities are backwards compatible with existing BSD print spooler facilities.

## 1.2 More Information

Much of the material in the LPRng documentation has been included in this document. For example, previous releases of LPRng had a large selection of README files; most of these are now incorporated into the HOWTO document.

Current information about LPRng and the latest release can be found on the LPRng web page:

http://www.astart.com/LPRng.html

There is also a mailing list at `lprng@iona.com`. To subscribe, send an email to `lprng-request@iona.com`. The body should contain only the word `subscribe'. To get off the list later on, repeat the same procedure, but use the word `unsubscribe'.

The LPRng distribution has a DOC directory that contains several documents that are very helpful. DOC/Intro.ps (Intro.txt for a slightly less readable text version) gives an overview of the BSD/LPRng printing model, and describes how LPRng carries out the printing process. DOC/Install.ps (or Install.txt) gives an overly detailed description of the LPRng installation and porting procedures; the README.installation file in the distribution is much shorter and contains all of the information needed for the average installer. The DOC/Tutorial.ps (or Tutorial.txt) is a very short tutorial that uses the non-privileged mode of LPRng which was designed for testing and tutorial purposes.

Several presentations of LPRng and print spooling software have been made at the Large Scale Installation Administrator (LISA) conferences and are in the LPRng distribution and available on web sites. LPRng - An Enhanced Printer Spooler System was presented at the LISA95 conference, and is in the LPRng distribution as DOC/LPRng-LISA95.ps. On a more general topic, the slides for the LISA97 tutorial on Printers and Network Print Spooling are also in the LPRng distribution in the DOC/LISA97 directory.

The LPRng distribution also has a set of man pages (in the man/ directory) that are the reference for the LPRng operation. When in doubt, please consult them.

## 1.3 Copyright

Material included in this document from the LPRng distribution Copyright Patrick Powell 1988-1997, where applicable.

The rights to distribute this document complete or in part are hereby granted for non-commercial purposes. Partial reproductions must acknowledge the source.

Permission to distribute this file together with LPRng and `derived works' (as defined in the LPRng license) is explicitly granted. This is allowed independent of the license under which the software is distributed.

Citing the document is allowed as long as the source is acknowledged.

## 1.4 Disclaimer

THE MATERIAL IN THIS HOWTO IS PROVIDED WITHOUT FEE AND AS-IS WITH NO WARRANTY REGARDING FITNESS OF USE FOR ANY PURPOSE. THE AUTHOR AND ALL CONTRIBUTORS ARE NOT LIABLE FOR ANY DAMAGES, DIRECT OR INDIRECT, RESULTING FROM THE USE OF INFORMATION PROVIDED IN THIS DOCUMENT.

## 1.5 Commercial Support

AStArt Technologies provides commercial support and enhancements for the LPRng and other network software. AStArt provides network and system consulting services for UNIX and NT systems, as well as real time and network software.

## 1.6 Web Site

Web Page:

http://www.astart.com/lprng.html

## 1.7 FTP Sites

The software may be obtained from
ftp://ftp.astart.com/pub/LPRng(Main site)

Mirrors:
ftp://ftp.sage-au.org.au/pub/printing/spooler/lprng (AU)
ftp://ftp.zod.wau.nl/pub/mirror/plp/LPRng (AU/NZ)
ftp://gwynne.cs.ualberta.ca/pub/LPRng (CA)
ftp://ftp.informatik.uni-hamburg.de/pub/os/unix/utils/LPRng (DE)
ftp://ftp.uni-paderborn.de/pub/unix/printer/plp/LPRng (DE)
ftp://ftp.iona.ie/pub/plp/LPRng (IE)
ftp://ftp.chembio.ntnu.no/pub/mirrors/LPRng (NO)
ftp://ftp.mono.org/pub/LPRng (UK)
ftp://ftp.cs.columbia.edu/pub/archives/pkg/LPRng (US)
ftp://ftp.cs.umn.edu/pub/LPRng (US)
ftp://ftp.iona.com/pub/plp/LPRng (US)
ftp://uiarchive.uiuc.edu/pub/packages/LPRng (US)

## 1.8 Mailing List

To join the LPRng mailing list, please send mail to lprng-request@iona.ie with the word 'subscribe' in the BODY

## 1.9 PGP Public Key

The LPRng distributions have an MD5 checksum calculated, which is then signed with a PGP public key. Here is the key for validating the checksums:

    Type Bits/KeyID    Date       User ID
    pub  1024/00D95C9D 1997/01/31 Patrick A. Powell <papowell@astart.com>
                                                              Patrick A. Powell <papowell@sdsu.edu>

    -----BEGIN PGP PUBLIC KEY BLOCK-----
    Version: 2.6.3i

    mQCNAzLygTQAAAEEANBW5fPYjN3wSAnP9xWOUc3CvsMUxjip0cN2sY5qrdoJyIhn
    qbAspBopR+tGQfyp5T7C21yfWRRnfXmoJ3FVtgToAsJUYmzoSFY08eDx+rmSqCLe
    rdJjX8aG8jVXpGipEo9U4QsUK+OKzx3/y/OaK4cizoWqKvy1l4lEzDsA2VydAAUT
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    vJvtf0UL/1/rGipbR+A0XHpHzJUMP9ZfJzKZjaK/d0ZBNlS3i+JnypypeQiAqo9t
    FV0OyUCwDfWybgAORuAa2V6UJnAhvj/7TpxMmCApolaIb4yFyKunHa8aBxN+17Ro
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    tpj0u5NfrotPTUw39n6YTgS5/aW0PQfO9dx7jVUcGeod1TGXTe9mIhDMwDJI4J14
    =3Zbp
    -----END PGP PUBLIC KEY BLOCK-----

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