Which distro do you see Cups listening on 0.0.0.0?
On Debian (at least, only one I have handy) it only listens on localhost.
[edit: I was wrong, it listens on 0.0.0.0 for UDP. I was only checking TCP. ]
[edit: I was wrong, it listens on 0.0.0.0 for UDP. I was only checking TCP. ]
A modern setup doesn't need it and doesn't use it.
But it looks like cups-browsed is only needed on the Internet; locally you only need mDNS.
I'm not sure why it deviates from Debian and Ubuntu which its based on though