CUPS "Unable to connect" error messages in error_log

English Network/Internet
1

Hi everyone

Since i am searching for a reason to my printing slowdown problems i found out that there are error messages about cups being unable to connect to an IP-Address in
our network on ipp port 631 every 33 seconds. I have several network printers installed, but this one is none of them. Maybe there was a printer with that address in the past,
but since there are no print jobs for this printer according to “lpstat -o” - i don’t know why cups wants to connect to it so desperately.

How can i find out why cups wants to connect to this host and how do i stop it?
And - just in case anyone knows - to analyze the mentioned slow-downs: How can i find out when exactly a print job has “left” the host - meaning the last network packet for that job has been transmitted to the printer.

The messages look as follows:

tail -n 2 /var/log/cups/error_log

E [02/May/2017:11:56:12 +0200] [cups-polld 133.98.6.186:631] Unable to connect to 133.98.6.186 on port 631.
E [02/May/2017:11:56:45 +0200] [cups-polld 133.98.6.186:631] Unable to connect to 133.98.6.186 on port 631.

Please don’t worry about the odd ip-range. this has nothing to do with it.

Thanks

2

You choose OTHER VERSION for the prefix of the thread title.

The fact that that is the first thing asked when starting a new thread should not only help you to tell us which openSUSE version you use, but it should also trigger you to tell that prominent in your thread when you are forced to choose OTHER VERSION. Somehow you did not understand that.

Please what version of openSUSE do you use?

3

It’s 13.2. In fact i was hoping that this would prove irrelevant and prevent people from answering: “You should have updated your system long ago” or anything like that.

However - maybe the described problem is just something i did not understand rather than a CUPS bug or something else that has changed recently.

4

When you do not want the obvious remarks about running an unsupported version, simply say that you are aware if this. People making such remarks only want to help you. They will not say things to you when it is obvious you know them.

And of course knowing what the version is may or may not be relevant (which you and I will only know after we know what is wrong), but many people will not even start thinking about your problem when they see that even what you must certainly know is not there.

And there may be people here still running 1 13.2 (I e.g. have 13.1 still running).
I do not think this is due to a recent change. After all, it is not supported, thus nothing changes.

Did you go into the CUPS GUI and check there for all printers and all Jobs?

5

Do you perhaps have a stale BrowsePoll directive address in cupsd.conf?

https://linux.die.net/man/8/cups-polld

6

Wireshark may be your best friend here (filtering to match the relevant printing protocols used).

You can also increase CUPS logging verbosity

sudo cupsctl --debug-logging

and monitor the CUPS logging with

sudo systemctl -fu cups

then send a print job and observe.

7

Interesting. There actually is a matching BrowsePoll directive in cupsd.conf and a “cups-polld” deamon is running.
Although i don’t know why - there is no suitable server here.

I wonder if i can safely stop it without disturbing printing. I don’t think i need a poll deamon - i configure my printers by hand and know the address in advance - there is no need to poll anything
(if i understand that expression correctly).

I will try out wireshark but i must figure out that filter stuff first.

Thank you very much.

8

Yes, you can safely comment it out or remove the unwanted entry entirely. You’ll need to restart CUPS for any changes you make to take effect.

sudo systemctl restart cups