Red Hat Bugzilla – Bug 105402
Duplicate "Listen 127.0.0.1:631" in cupsd.conf (even after bugfix 88303)
Last modified: 2007-04-18 12:57:49 EDT
Description of problem: With two ethernet interfaces, any attempt to set up a printer to share to two subnets produces a duplicate "Listen 127.0.0.1:631" line in /etc/cups/cupsd.conf. In our case we have eth0 (subnet 128.100.216.0/255.255.255.0) and eth1 (private 192.168.216.0/255.255.255.0). Initially we had cups set to listen to @IF(eth0) and @IF(eth1) - that all worked fine. Then we decided it would be better to swit ch to explicitly specifying the IP subnets, in case we later add virtual interfaces. So instead of one "Ethernet eth0 and eth1" line in the configuration tool, we added two lines: one for 128.100.216.0/255.255.255.0 and the other for 192.168.216.0/255.255.255.0. This produced the following cupsd.conf: Listen 127.0.0.1:631 Listen 128.100.216.10:631 Listen 192.168.216.10:631 Listen 127.0.0.1:631 <---- duplicate! Note - this is different from bug 88303. I am already running the errata version 0.6.47.11-1 which contains a fix for that bug. The problem is the following section of code in util/backend.py: -------------------- # Interfaces to listen on if len (ipaddr) != 1 or ipaddr[0] != "*": cupsd_conf_lines.append ("Listen 127.0.0.1:631\n") for each in ipaddr: cupsd_conf_lines.append ("Listen %s:631\n" % each) --------------------- If "127.0.0.1" shows up in the ipaddr list, there will be a duplicate Listen line generated. This causes cupsd to crash and refuse to start until the /etc/cups/cups.conf file is fixed by hand. The fix for bug 88303 eliminates duplicates in ipaddr but it doesn't eliminate 127.0.0.1 from that list. I have resolved the problem on our site by changing the above lines to: ---------------------- # Interfaces to listen on wrote_localhost = 0 if len (ipaddr) != 1 or ipaddr[0] != "*": cupsd_conf_lines.append ("Listen 127.0.0.1:631\n") wrote_localhost = 1 for each in ipaddr: if each != "127.0.0.1" or not wrote_localhost: cupsd_conf_lines.append ("Listen %s:631\n" % each) ------------------------ This resolves the problem; however, I'm still not sure that the logic of writing a separate "Listen 127.0.0.1:631" line is correct in the first place ...
I can't seem to reproduce this problem unless I explicitly list 127.0.0.0/255.255.255.0 as a network interface to listen on. Is that what you've done?
(I'm afraid your reply got lost from bugzilla due to a hardware problem; I had a copy in my mailbox though:) ---> No. I simply shared out the printer to two subnets, on different ethernet interfaces. Here is a procedure to duplicate the problem (which really shouldn't be necessary; just look at the code! It shows quite clearly how the two lines get added). * Install two ethernet cards in a machine. * Install RedHat Linux 9. Assign IP addresses A.B.C.D and E.F.G.H to the two network cards. * Upgrade to latest errata * Run redhat-config-printer * Add a local printer and click Apply. * Choose "Sharing" from the Action menu for that printer. * Remove the default "All Hosts" entry. * Add an entry and specify the firs subnet IP address and mask: A.B.C.0/255.255.255.0 * Add a second entry for the second subnet: E.F.G.0/255.255.255.0 * Click Apply. The cupsd.conf file now has two "Listen 127.0.0.1:631" lines. And here is another bug: when I do it this way, there is no listen line for A.B.C.D, just for E.F.G.H! Unless I also explicitly turn on sharing to the ethernet card via @IF(eth0) as well! <---
If possible, could you try redhat-config-printer-0.6.76-1, which is in rawhide at the moment? It contains further fixes in this area, and I'd like to verify that it fixes the original problem.
Yes, the new redhat-config-printer-0.6.76-1 does fix the original problem. It also seems to fix the second problem I noticed when making the previous reply. Now both subnet IP addresses get listed as they should (instead of just the second one), and the localhost address 127.0.0.1 gets listed just once as it should (instead of twice). Thanks!
Fixed in CVS.
An errata has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on the solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHBA-2004-071.html