Printing Setup August 2011

This document is intended as a brain dump of the important things to know about the new printer setup. Comments and suggestions for additions welcome.

For this new semester, we are introducing charging for printing on the level 3, 4 and 5 student lab printers at Appleton Tower. This is being achieved by making use of the central pcounter mechanism. IS have set up pcounter queues for the 6 chargeable printers and we have set up a new cups server which prints to the printers via the pcounter queue. Details of how all this works can be found below.

For the moment, the setup for our remaining printers at AT and the Forum remains unchanged though it seems likely that in the future we will at least introduce authenticated printing to these printers.

The Pcounter set-up

The new print server is called tetra. It is a virtual machine running on central at the moment though that may change as our backup plan requires giving tetra direct access to the printers (circumventing Pcounter) and Central does not currently carry the printer wire. It is running sl6 and version 1.4.7 of CUPS, This is the first version of CUPS in which the kerberos implementation seems to do what you would expect. Tetra has an alias of atkrbcups but this is not in use at the moment (see below). To ensure that users cannot make free with each other's pcounter credit, tetra uses Kerberos authentication when accepting connections. Currently authenticated printing does not work from Windows or Mac-OS machines so to allow self-managed users to still print, a web front end to the printing system has been provided at This web front end is Cosign authenticated and also runs on tetra and is set up by cups-kerborised-server.h.

Tetra is mainly configured by the dice/options/cups-kerborised-server.h header file (yes, I know I mis-spelled kerberos thank you). There is an equivalent live file for emergency changes though at time of writing Tetra is still on the development release. There's no reason why it couldn't be moved to the stable release. The actual print queues are configured from another live header file live/cups-lpd-printers.h. The names of the new print queues (and their old equivalents are:

Queue Old Name Hostname
lpd:// at3 guimard
lpd:// at13c harrel
lpd:// at14 chandler
lpd:// at7 chelios
lpd:// at10c luse
lpd:// at17 sabon

the old queue names have been retained for the moment via the CUPS classes mechanism. This should be configurable via the component but I couldn't get it to work (though I have not had much time to look at this). For the moment the classes are configured manually.

The student lab machines are configured to use tetra as their print server via the /etc/cups/client.conf file. This is in turn created by the file component from resources in live/include/live/studentlabs-at.h. the client.conf file currently specifies tetra directly as the server. This should really be the alias atkrbcups but this needs an addition to the CUPS configuration file /etc/cups/cupsd.conf on tetra which is currently not supported by the component. We are talking to the component author (Kenny McDonald ) about adding this to the component.

IS Administration

Our main contact at IS is Thomas Gooddy ( He is on holiday until after the start of term and has given Angus Rae's name as the person to contact in the meantime.

Giving the students Pcounter credits at the start of the year

Thomas says:

To get student credit added create a csv file with the uuns and the credit amount, then pass this onto the IS ITI Lrn. &Tch. Spaces Tech. section via a unidesk call. Please give them plenty of notice if possible. They will then raise an EIT to bill informatics for the amount being credited.

Giving students extra credits

Thomas says

For checking\amending balances you are sadly stuck in the Windows world, either via a gui or a command line tool.

Gui: \\ed\dst\UnManaged\PCounter\PCounter_Admin.hta
Commandline: \\ed\dst\UnManaged\PCounter\account.exe

The GUI is incredibly slow so I suggest using the account.exe command line tool

Update neilb 19/9/2011 - I found that if I used the tools in the v2.40c sub dir, it worked fine.

-- CraigStrachan - 30 Aug 2011

Topic revision: r4 - 19 Sep 2011 - 09:40:09 - NeilBrown
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