[cups] CUPS questions

[Michael Sweet]

Dmitry,

> On Sep 17, 2016, at 3:25 AM, Dmitry Voronin <carriingfate92 at yandex.ru> wrote:
> 
> 
> Hello,
> 
> I have some questions about CUPS. Today we use CUPS 2.1.3 on Debian 8.
> 
> 1. Why CUPS service run by superuser (root)? As for me, it's very dangerous for security, because if someone can get unauthorized access, he can operate with superuser rights. So, can CUPS will be run with ordinary user (not root)?

Because some things (like listening and binding to privileged ports, controlling sandbox/security policies, supporting Kerberos as a server, etc.) require root access.

> 2. Why directory /var/spool/cups has group lp? Is it needed for utilites like lp, lpstat and so on?

No, for the filters and backends which run under that user and group.

> 3. We develop application with GUI, that can operate with user jobs. Updating of list of jobs is implemented by subscription mechainsm. We would like to have in attributes, that we get by IPP request Get-Notifications, attribute job-originating-user-name.
> Or we would like to create subscription on job's events, in witch we have data of events by user.

You can subscribe to events on printers, which will give you all of the status updates for jobs on that printer. Use a Get-Job-Attributes request to get all of the job attributes.

> 4. We think that attribute of IPP request Get-Jobs 'limit' should define number of jobs with end (not with start, as now).

I don't understand your request - Get-Jobs lists jobs in different orders depending on which jobs you request.

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Michael Sweet, Senior Printing System Engineer