[cups.bugs] CUPS and Shorewall firewall interfering with each other

Erik Reuter ereuter at erikreuter.net
Thu Dec 30 07:19:43 PST 2004


I'm having a problem with CUPS and the Shorewall firewall interfering
with each other.

   Linux kernel 2.6.9
   CUPS 1.1.22-2
   Shorewall 2.0.13

CUPS was working fine to print to my Epson C84 (network connected via a
Netgear PS101 print server using lpd://PS101.IP.address/raw ) until I
installed the Shorewall firewall on the machine running CUPS.

When I installed Shorewall, I opened up port 515 for lpd printing from
the firewall to the local network

   ACCEPT          fw              loc             tcp     515  # LPD

so I didn't anticipate any problems with CUPS printing.

However, as soon as I started the Shorewall firewall, I found that I
could no longer print from the firewall machine using CUPS.

Okay, my first thought was that I had to open more ports in the
firewall. So I checked the Shorewall packet reject log to see which
ports I would need to open. Surprisingly, NO PACKETS RELATED TO PRINTING
HAD BEEN REJECTED. It was not a logging problem, because there were
packets occasionally being rejected, but not during the times when I was
trying to print.

Just to make sure, I put a couple lines in my Shorewall policy file to
open ALL ports between fw<->loc , and I still could not print.

So, with the exception of printing with CUPS, the Shorewall firewall
is working with all of my other programs. And with the exceptions of
Shorewall, the CUPS printing works with all of my other programs. But I
cannot use CUPS and Shorewall together, since they seem to interfere.

How can I find out the source of the interference? What is the best way
to troubleshoot this?

Here's some output from the end of the CUPS log from when I try a print
job:


D [28/Dec/2004:12:05:40 -0500] [Job 9] GIMP-PRINT tossing right 0
I [28/Dec/2004:12:05:40 -0500] [Job 9] Finished page 1...
d [28/Dec/2004:12:05:40 -0500] PID 7522 exited with no errors.
D [28/Dec/2004:12:05:40 -0500] [Job 9] GIMP-PRINT: Image_height 3915
D [28/Dec/2004:12:05:40 -0500] [Job 9] GIMP-PRINT: Image_width 3060
D [28/Dec/2004:12:05:40 -0500] [Job 9] GIMP-PRINT: Image_width 3060
D [28/Dec/2004:12:05:40 -0500] [Job 9] GIMP-PRINT: Image_height 3915
D [28/Dec/2004:12:05:40 -0500] [Job 9] GIMP-PRINT: Image_height 3915
D [28/Dec/2004:12:05:40 -0500] [Job 9] GIMP-PRINT: Image_width 3060
I [28/Dec/2004:12:05:40 -0500] [Job 9] Ready to print.
I [28/Dec/2004:12:05:40 -0500] [Job 9] Attempting to connect to host
192.168.0.1
9 for printer raw
d [28/Dec/2004:12:05:40 -0500] PID 7523 exited with no errors.
d [28/Dec/2004:12:05:41 -0500] select_timeout: 11 seconds to process
active jobs






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