Bug 459610

Summary:	Turning off IPv6 "breaks" printing
Product:	[Fedora] Fedora	Reporter:	Tom London <selinux>
Component:	cups	Assignee:	Tim Waugh <twaugh>
Status:	CLOSED NOTABUG	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	rawhide
Target Milestone:	---
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2008-08-20 15:12:31 UTC	Type:	---
Regression:	---	Mount Type:	---
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Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Tom London 2008-08-20 14:31:15 UTC

Description of problem:
I (tried to) turn off IPv6 on my rawhide system (due to issues with name severs, sigh), and I noticed that printing (say, from firefox) stopped working. (I unchecked all IPv6 boxes in s-c-network,  added "install ipv6 /bin/true" and rebooted).

Checking /var/log/cups/error_log, I noticed:
E [20/Aug/2008:06:14:08 -0700] Unable to open listen socket for address ::1:631 - Address family not supported by protocol.
I [20/Aug/2008:06:14:08 -0700] Listening to /var/run/cups/cups.sock on fd 4...

and

[tbl@localhost ~]$ curl http://localhost:631
curl: (7) couldn't connect to host
[tbl@localhost ~]$ 

Firewall settings are fine.

Noticed also that /etc/hosts only has entry for '::1' for localhost:
# Do not remove the following line, or various programs
# that require network functionality will fail.
::1	localhost.localdomain	localhost
[tbl@localhost ~]$ 

Adding an IPv4 entry for localhost and restarting cups "makes this work for me":
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 localhost.localdomain localhost
::1	localhost.localdomain	localhost
[tbl@localhost ~]$ 

and 

I [20/Aug/2008:07:06:58 -0700] Listening to 127.0.0.1:631 (IPv4)
I [20/Aug/2008:07:06:58 -0700] Listening to /var/run/cups/cups.sock (Domain)

Should the above (i.e., "hard removal of IPv6") work? 

Version-Release number of selected component (if applicable):
cups-1.3.8-4.fc10.i386

How reproducible:
Every time

Steps to Reproduce:
1.
2.
3.
  
Actual results:


Expected results:


Additional info:

Comment 1 Tim Waugh 2008-08-20 15:12:31 UTC

(In reply to comment #0)
> Checking /var/log/cups/error_log, I noticed:
> E [20/Aug/2008:06:14:08 -0700] Unable to open listen socket for address ::1:631
> - Address family not supported by protocol.
> I [20/Aug/2008:06:14:08 -0700] Listening to /var/run/cups/cups.sock on fd 4...

So it's listening on the UNIX domain socket.

> [tbl@localhost ~]$ curl http://localhost:631
> curl: (7) couldn't connect to host
> [tbl@localhost ~]$ 

Well, it isn't listening on the IPv4 port; it hasn't been told to.  It's listening on port 631 of 'localhost', whichever addresses that happens to resolve to -- in your case, the IPv6 localhost address.

It's a known bug in GTK+ that the print dialog (as used by e.g. Firefox) doesn't use the UNIX domain socket: bug #455742.

I expect you'll find that 'lp' etc work fine. :-)

There's no CUPS bug here.