[PLUG] Turning off cups broadcast

Keith Lofstrom keithl at kl-ic.com
Tue Feb 20 08:31:09 PST 2007


Cups has a neat feature called autodiscovery, which allows computers
to share printers by default.  This feature is turned on by default,
no doubt so things "just work" for newbies.

In my case, I don't want to advertise my printer queues from my
machines, especially my laptop while roaming.  There are some lines
in /etc/cups/cupsd.conf:
---------------------------------------------------------------------
#
# Browsing: whether or not to broadcast and/or listen for CUPS printer
# information on the network.  Enabled by default.
#

#Browsing On

----------------------------------------------------------------------

One would think that adding the line:

----------------------------------------------------------------------
Browsing Off
----------------------------------------------------------------------

... would turn off the feature, but NO.   It keeps on spewing discovery
packets on port 631 to the broadcast address.  I finally turned this off
with the line:

----------------------------------------------------------------------
BrowseInterval  0
----------------------------------------------------------------------

Perhaps this will cause something odd to fail, like the guest printers
on my vmware host-only network.   But it is annoying sometimes;  I find
the damnedest printers popping up in /var/log/cups/error_log from while
roaming, no doubt from all the other laptops on the wireless broadcasting
their printers to the world.  At Linux clinic on Sunday, somebody was
broadcasting  store_4000  and  monkeyhouse,  for example.  Perhaps I
should have sent them a ransom note that would print when they got home.

On my home network,  I have iptables cranked up to high paranoia with
logging, and I was annoyed to see the broadcast packets from the laptop.
It took a while to figure out where they were coming from.   Hence this
message, for all the rest of you wondering where the ipp (port 631)
packets are coming from.

Keith

---
Keith Lofstrom          keithl at keithl.com         Voice (503)-520-1993
KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon"
Design Contracting in Bipolar and CMOS - Analog, Digital, and Scan ICs



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