CUPS Broadcast-Scan


I experience the problem that a Mac regularly floods the net by doing a broadcast-scan on port 631. I know of that feature in the Common Unix Printing System(CUPS). Coming from text-based unices my first guess was to edit /etc/cupsd/cupsd.conf and switch from "Browsing on" to "Browsing off". Unfortunately it seems config-files in OS X are read-only. My second try was to untag the "Share printers with others" box in the System/Printer configuration menu, which seems to have nothing to do with the active browsing search. That leaves me with no further known options - help will be appreciated.
Thanks in advance,
Alain M. Lafon