Authenticated Printing for the AT Computing Labs

A Lot of Trees

Over 200000 sides of paper per month are printed within the School during term time, more than half of them emerging from the 6 AT computing lab printers. At a rough cost of 5p per side for mono printing and 30p per sheet for colour, this adds up to a considerable amount of money over the course of a year. We have been devoting a great deal of thought to how we can reduce printing costs within the School. The monthly mailings to users detailing their printer usage are one outcome from those deliberations.

As some users with unexpectedly high totals have found out, these monthly mailings highlight one problem with our current printing setup, namely that printing within the School is entirely unauthenticated. This means that the user when submitting a print job can specify any user name they please and that will be the name the job is credited to. This is clearly unsatisfactory.

Fortunately, the printing system we use, CUPS, includes support for Kerberos authenticated printing and so the decision has been taken to make a test deployment of authenticated printing to the six printers in the AT computing labs, namely at3, at7, at10c, at13c, at14 and at17.

What Does This Mean For Me?

We are introducing a new print server, atkrbcups for the AT lab printers. This server will only have access to the 6 lab printers mentioned above and will be the default print server for lab machines. At the same time, we will be removing the queues for the lab printers from the old print server, infcups, so that the only way to access the lab printers will be through the new authenticated print server. Once this new server is in place, anyone wishing to print to a lab printer will need to have valid kerberos credentials in place. Users of the DICE machines within the labs should notice no difference since they should have already acquired these credentials as part of the normal DICE login process. Users attempting to print from self managed machines will notice a considerable difference since at time of writing (22/7/11) authenticated printing from any variety of Windows or Mac OS simply does not work. Printing from self managed Linux machines should work providing that

  • The version of Kerberos on the machine is either Heimdal or MIT Kerberos version 1.6.3 or later
  • The user has obtained credentials from the INF.ED.AC.UK realm.

We are investigating the problems with Windows and Mac OS and the intention is to enable printing from these platforms as soon as the issues are identified and rectified. In the mean time, we have provided a Cosign protected web front end to the printing system which users of any operating systems can use to print. This can be found at

With the move to authenticated printing, we are taking the opportunity to change the names of the lab printers to something more meaningful along the lines of the printer names used within the Forum. The new printer names will be:

Old Name New Name
at3 at5corm0
at7 at4labm0
at10c at4labc0
at13c at5corc0
at14 at5westm0
at17 at3labm0

The old names will continue to work for the time being.

We hope that users will appreciate the need to address the amount of printing being done within the School and will not find the new set-up too onerous. If you have any questions about any of this, please contact the User Support Unit in the first instance via the support form

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2 Responses to Authenticated Printing for the AT Computing Labs

  1. A says:

    200,000 pages is ridiculous…
    Why not charge at least something small? 1p per black and white page would cover 20% of the costs for it. That’s quite a substantial reduction in your costs – meanwhile informatics students arn’t burdening much cost at 1p per page – you won’t get anywhere better than that!

    Or even accepting printing donations, i’d be happy to contribute something towards printing personally and feel bad a few times when i’ve needed to print out large amounts of things (mostly around coursework/revision time) and cannot do so!

  2. David says:

    Why not only start charging past a certain usage. It seams there are many people that take advantage of the free printing and will print out entire e-books just because it’s free. Then there are the people the print out non-informatics related material, e.g. 100+ copies of that party their hosting Friday night. These people consciously go to AT to exploit the free printing.

    A rough calculation tells me that each student would have to print about 100 sheets of paper per month, As an informatics student I only print in AT, but I doubt I use any where near that much each month.

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