lprng-devel

[Lprng-devel] how to prevent lprm-ing a spooled, active job to avoid accounting

[Iordan I. <io...@cd...>]

Hello everyone,

It took me a little while to find the new mailing list (I was trying to 
subscribe to the old one). We are thinking of making use of lprng at the 
Dept. of Computer Science at University of Toronto, and I am currently 
making sure it will work within our environment.

How does one prevent a user from sending a job, and when the job has 
been spooled onto the printer (our printers spool), to lprm it, thus 
avoiding our accounting mechanism? Yes, with 5000 users, we are forced 
to do some form of accounting, otherwise the printers will be constantly 
empty and out of toner... Our users print stuff completely unrelated to 
their CS courses all the time :)

One way to deal with this would be to prevent users from removing the 
*active* job on the queue, right? I guess an evil hack would be to wrap 
lprm, but that won't prevent savvy users from finding the real lprm and 
just using it.

Another way would be to acknowledge the lprm request, and to stop 
sending data to the printer if data is still being sent, but to then let 
the (ifhp) filter continue with its accounting work.

I am successfully doing accounting with ifhp, and it's working great, 
except for lprng being quite compliant in allowing users to wipe out 
their own active jobs...

Many thanks in advance,
Iordan Iordanov

Re: [Lprng-devel] how to prevent lprm-ing a spooled, active job to avoid accounting

[Craig S. <csm...@en...>]

On Fri, Mar 18, 2011 at 05:09:39PM -0400, Iordan Iordanov wrote:
> How does one prevent a user from sending a job, and when the job has 
> been spooled onto the printer (our printers spool), to lprm it, thus 
> avoiding our accounting mechanism? Yes, with 5000 users, we are forced 
> to do some form of accounting, otherwise the printers will be constantly 
> empty and out of toner... Our users print stuff completely unrelated to 
> their CS courses all the time :)
Those sneaky CS students, I rememeber in my day.. but i digress.

Would two queues do what you are after? one public queue and then push
the job to the second queue which cannot have jobs removed?

 - Craig
-- 
Craig Small VK2XLZ    http://www.enc.com.au/       csmall at : enc.com.au
Debian GNU/Linux      http://www.debian.org/       csmall at : debian.org
GPG fingerprint:       1C1B D893 1418 2AF4 45EE  95CB C76C E5AC 12CA DFA5

Re: [Lprng-devel] how to prevent lprm-ing a spooled, active job to avoid accounting

[Bernhard R. L. <br...@de...>]

* Craig Small <csm...@en...> [110319 12:34]:
> On Fri, Mar 18, 2011 at 05:09:39PM -0400, Iordan Iordanov wrote:
> > How does one prevent a user from sending a job, and when the job has 
> > been spooled onto the printer (our printers spool), to lprm it, thus 
> > avoiding our accounting mechanism? Yes, with 5000 users, we are forced 
> > to do some form of accounting, otherwise the printers will be constantly 
> > empty and out of toner... Our users print stuff completely unrelated to 
> > their CS courses all the time :)
> Those sneaky CS students, I rememeber in my day.. but i digress.
>
> Would two queues do what you are after? one public queue and then push
> the job to the second queue which cannot have jobs removed?

If anyone has time, looking at job removal would be nice. There is also
the problem that if a filter rejects a job, the rejection message is
stored in that job but the job then removed so one gets "mysterious"
errors. Perhaps lprng needs to keep removed jobs a bit longer so that
accounting information and error messages are kept long enough.

	Bernhard R. Link

Re: [Lprng-devel] how to prevent lprm-ing a spooled, active job to avoid accounting

[Iordan I. <io...@cd...>]

Hi Craig,

On 03/19/11 07:15, Craig Small wrote:
 > Would two queues do what you are after? one public queue and then push
 > the job to the second queue which cannot have jobs removed?

I had no idea that this could even be done. I'll look into it today.

Over the weekend I was thinking of doing something rougher than that.

The accounting script is called twice by ifhp - once in the beginning 
and once at the end (filestart and fileend). At filestart, for job M, I 
was thinking of dropping a file in (for example) 
"/var/run/printaccounting/printerN" with a username and pagecountM, and 
at fileend, removing that file. If the next printjob in printerN's spool 
"finds" a file in the directory, it can "correct" the quota of username 
by (pagecountM+1 - pagecountM).

That's a bit of a hack though. So I take it there is no neat way to tell 
LPD to disallow removal of active jobs? In most academic environments 
with enterprise printers, the removal of an "active" job does nothing 
because the job has been spooled anyway!

Cheers,
Iordan