[SOLVED] CUPS web admin tool at localhost:631 not responding

ferrari · 04-28-2020, 12:50 AM

Are you accessing this virtual machine via its local desktop? That is are you using a browser on the guest itself, or are you trying to reach it's CUPS server web interface externally eg via the host?

lambdrum · 04-28-2020, 12:54 AM

Ferrari,

I am using the desktop and Firefox within the same virtual machine, not the host.

ferrari · 04-28-2020, 01:00 AM

Run

Code:

wget -p localhost:631 -O test.out

That should produce something like

Code:

~> wget -p localhost:631 -O test.out
WARNING: combining -O with -r or -p will mean that all downloaded content
will be placed in the single file you specified.

--2020-04-28 17:58:48--  http://localhost:631/
Resolving localhost (localhost)... ::1, 127.0.0.1
Connecting to localhost (localhost)|::1|:631... connected.
HTTP request sent, awaiting response... 200 OK
Length: 2362 (2.3K) [text/html]
Saving to: ‘test.out’

test.out                           100%[===============================================================>]   2.31K  --.-KB/s    in 0s      

2020-04-28 17:58:48 (692 MB/s) - ‘test.out’ saved [2362/2362]

Loading robots.txt; please ignore errors.
--2020-04-28 17:58:48--  http://localhost:631/robots.txt
Reusing existing connection to [localhost]:631.
HTTP request sent, awaiting response... 200 OK
Length: 95 [text/plain]
Saving to: ‘test.out’

test.out                           100%[===============================================================>]      95  --.-KB/s    in 0s      

2020-04-28 17:58:48 (29.2 MB/s) - ‘test.out’ saved [95/95]

FINISHED --2020-04-28 17:58:48--
Total wall clock time: 0.07s
Downloaded: 2 files, 2.4K in 0s (368 MB/s)

with the web page elements saved to test.out as well. Don't worry about posting the output, unless you get errors or 'connection refused' etc

lambdrum · 04-28-2020, 01:09 AM

I received some errors:
Connecting to localhost (localhost) ::.110|631... failed: Connection timed out. There were more numbers before the 110
connecting to localhost (localhost) ::.169|631... failed: connection timed out. There were more numbers before the 169

Then it went on to try again and fail again

ferrari · 04-28-2020, 01:47 AM

When the connection timeout occurs, get the current cups.service status with

Code:

sudo systemctl status cups

If necessary, restart the service

Code:

sudo systemctl restart cups

and immediately try reaching the web interface via your browser. Any different?

Just in case this thread is relevant...
https://www.linuxquestions.org/quest...ks-4175590585/

ferrari · 04-28-2020, 04:15 AM

Quote:

Originally Posted by lambdrum

I received some errors:
Connecting to localhost (localhost) ::.110|631... failed: Connection timed out. There were more numbers before the 110
connecting to localhost (localhost) ::.169|631... failed: connection timed out. There were more numbers before the 169

Then it went on to try again and fail again

This looks like localhost is not configured, but others may be able to advise further here.

Check that /etc/hosts contains the following entry

Code:

127.0.0.1       localhost

Run

Code:

host localhost

Check that you get the following response...

Code:

localhost has address 127.0.0.1
localhost has IPv6 address ::1

ferrari · 04-28-2020, 04:38 AM

Just in case this is relevant...
https://unix.stackexchange.com/quest...st-connections

lambdrum · 04-28-2020, 11:44 PM

Quote:

Originally Posted by ferrari

When the connection timeout occurs, get the current cups.service status with

Code:

sudo systemctl status cups

If necessary, restart the service

Code:

sudo systemctl restart cups

and immediately try reaching the web interface via your browser. Any different?

Just in case this thread is relevant...
https://www.linuxquestions.org/quest...ks-4175590585/

Hello Ferrari,
it appears we are making some progress:

● cups.service - CUPS Scheduler
Loaded: loaded (/usr/lib/systemd/system/cups.service; enabled; vendor preset: disabled)
Active: active (running) since Tue 2020-04-28 21:00:15 PDT; 25min ago
Docs: man:cupsd(8)
Main PID: 1626 (cupsd)
Status: "Scheduler is running..."
Tasks: 1 (limit: 8902)
Memory: 2.0M
CGroup: /system.slice/cups.service
└─1626 /usr/sbin/cupsd -l

Apr 28 21:00:15 localhost.localdomain systemd[1]: Starting CUPS Scheduler...
Apr 28 21:00:15 localhost.localdomain systemd[1]: Started CUPS Scheduler.
Apr 28 21:00:46 localhost.localdomain cupsd[1626]: Unable to finalize "/etc/cups/printers.conf": Permission denied
Apr 28 21:05:43 localhost.localdomain cupsd[1626]: REQUEST localhost - - "POST / HTTP/1.1" 200 361 Create-Printer-Subscriptions successful-ok
Apr 28 21:05:47 localhost.localdomain cupsd[1626]: REQUEST localhost - - "POST / HTTP/1.1" 200 151 Cancel-Subscription client-error-not-found
Apr 28 21:23:28 localhost.localdomain cupsd[1626]: REQUEST localhost - - "POST / HTTP/1.1" 200 151 Cancel-Subscription client-error-not-found

The unable to finalize "/etc/cups/printers.conf" may be a problem. And i learned how to copy and paste in the terminal. Thoughts on what to do about the above anyone?

I did read the link provided, and it did not look like the bug was fixed except in a release. The one solution i saw was not recommended it looked like:

/lib/systemd/system/cups.socket

adding a line

ListenStream=631

in the "[Socket]" section. The file should look like this then:

----------
[Unit]
Description=CUPS Scheduler

[Socket]
ListenStream=/var/run/cups/cups.sock
ListenStream=631

[Install]
WantedBy=sockets.target

lambdrum · 04-28-2020, 11:58 PM

Quote:

Originally Posted by ferrari

This looks like localhost is not configured, but others may be able to advise further here.

Check that /etc/hosts contains the following entry

Code:

127.0.0.1       localhost

Run

Code:

host localhost

Check that you get the following response...

Code:

localhost has address 127.0.0.1
localhost has IPv6 address ::1

Ferrari,

It almost looks like there are no contents in the /etc/hosts file. I ran cat /etc/hosts and nothing happened.

Is there a way to delete CUPS and then reinstall it?

ferrari · 04-29-2020, 12:08 AM

Quote:

It almost looks like there are no contents in the /etc/hosts file. I ran cat /etc/hosts and nothing happened.

Ok, add the localhost entries (or at least the IPv4 address) as above to /etc/hosts, with an editor as root eg using nano...

Code:

sudo nano /etc/hosts

When done, save and reboot. Now you should be able to ping localhost

Code:

ping localhost

and further to that you should now be able to reach the CUPS web interface in the browser using "localhost:631".

BTW, even without that hostname it should siall have been possible to use the localhost IP address "127.0.0.1:631"

Quote:

Is there a way to delete CUPS and then reinstall it?

This appears to be a fundamental network issue with "localhost" hostname missing.

ferrari · 04-29-2020, 12:18 AM

Quote:

Originally Posted by lambdrum

Hello Ferrari,
it appears we are making some progress:

● cups.service - CUPS Scheduler
Loaded: loaded (/usr/lib/systemd/system/cups.service; enabled; vendor preset: disabled)
Active: active (running) since Tue 2020-04-28 21:00:15 PDT; 25min ago
Docs: man:cupsd(8)
Main PID: 1626 (cupsd)
Status: "Scheduler is running..."
Tasks: 1 (limit: 8902)
Memory: 2.0M
CGroup: /system.slice/cups.service
└─1626 /usr/sbin/cupsd -l

Apr 28 21:00:15 localhost.localdomain systemd[1]: Starting CUPS Scheduler...
Apr 28 21:00:15 localhost.localdomain systemd[1]: Started CUPS Scheduler.
Apr 28 21:00:46 localhost.localdomain cupsd[1626]: Unable to finalize "/etc/cups/printers.conf": Permission denied
Apr 28 21:05:43 localhost.localdomain cupsd[1626]: REQUEST localhost - - "POST / HTTP/1.1" 200 361 Create-Printer-Subscriptions successful-ok
Apr 28 21:05:47 localhost.localdomain cupsd[1626]: REQUEST localhost - - "POST / HTTP/1.1" 200 151 Cancel-Subscription client-error-not-found
Apr 28 21:23:28 localhost.localdomain cupsd[1626]: REQUEST localhost - - "POST / HTTP/1.1" 200 151 Cancel-Subscription client-error-not-found

The unable to finalize "/etc/cups/printers.conf" may be a problem. And i learned how to copy and paste in the terminal. Thoughts on what to do about the above anyone?

First thoughts are to check the CUPS config file ownerships/permissions...

Code:

ls -l /etc/cups

lambdrum · 04-29-2020, 12:21 AM

Ferrari,

You have solved the issue and have the patience of a saint! i am able to access the CUPS web admin page and it appears i am in business. I cannot thank you enough. Any idea why this may have happened? or did i just probably delete or mess with something i should not have?

--- localhost ping statistics ---
284 packets transmitted, 284 received, 0% packet loss, time 1064ms
rtt min/avg/max/mdev = 0.021/0.037/0.384/0.030 ms

This has been resolved.

lambdrum · 04-29-2020, 12:24 AM

Quote:

Originally Posted by ferrari

First thoughts are to check the CUPS config file ownerships/permissions...

Code:

ls -l /etc/cups

This is the results from ls -l /etc/cups

[user1@localhost ~]$ ls -l /etc/cups
total 92
-rw-------. 1 root lp 0 Mar 26 2019 classes.conf
-rw-r--r--. 1 root lp 0 Mar 26 2019 client.conf
-rw-r--r--. 1 root root 27707 Apr 25 2019 cups-browsed.conf
-rw-r-----. 1 root lp 6278 Mar 26 2019 cupsd.conf
-rw-r-----. 1 root lp 6278 Mar 26 2019 cupsd.conf.default
-rw-r-----. 1 root lp 3000 Apr 25 2019 cups-files.conf
-rw-r-----. 1 root lp 3000 Mar 26 2019 cups-files.conf.default
-rw-r--r--. 1 root lp 17 Apr 26 18:25 lpoptions
drwxr-xr-x. 2 root lp 4096 Mar 26 2019 ppd
-rw-------. 1 root lp 429 Apr 26 19:08 printers.conf
-rw-------. 1 root lp 501 Apr 28 22:16 printers.conf.N
-rw-------. 1 root lp 491 Apr 26 19:02 printers.conf.O
-rw-r--r--. 1 root lp 142 Mar 26 2019 snmp.conf
-rw-r-----. 1 root lp 142 Mar 26 2019 snmp.conf.default
drwx------. 2 root lp 4096 Mar 26 2019 ssl
-rw-r-----. 1 root lp 712 Apr 28 22:16 subscriptions.conf
-rw-r-----. 1 root lp 412 Apr 28 22:04 subscriptions.conf.O

ferrari · 04-29-2020, 12:49 AM

Quote:

Originally Posted by lambdrum

Ferrari,

You have solved the issue and have the patience of a saint! i am able to access the CUPS web admin page and it appears i am in business. I cannot thank you enough. Any idea why this may have happened? or did i just probably delete or mess with something i should not have?

--- localhost ping statistics ---
284 packets transmitted, 284 received, 0% packet loss, time 1064ms
rtt min/avg/max/mdev = 0.021/0.037/0.384/0.030 ms

This has been resolved.

I'm really not sure why that file was missing. The default configuration should have been there from install. Anyway, glad to read of your progress. All part of the learning.

ferrari · 04-29-2020, 12:52 AM

The permissions of the listed files look ok to me. Just let us know if you have any problems configuring CUPS.