Suppose, not hypothetically , that you have a central CUPS print server, and that people also have Linux desktops or laptops that they point at your print server to print to your printers. As of at least Ubunut 24.04, if you're doing this you probably want to get people to turn off and disable cups-browsed on their machines. If you don't, your central print server may see a constant flood of connections from client machines running cups-browsed. You're probably running it, as I believe that cups-browsed is installed and activated by default these days in most desktop Linux environments.

(We didn't really notice this in prior Ubuntu versions, although it's possible cups-browsed was always doing something like this and what's changed in the Ubuntu 24.04 version is that it's doing it more and faster.)

I'm not entirely sure why this happens, and I'm also not sure what the CUPS requests typically involve, but one pattern that we see is that such clients will make a lot of requests to the CUPS server's /admin/ URL. I'm not sure what's in these requests, because CUPS immediately rejects them as unauthenticated. Another thing we've seen is frequent attempts to get printer attributes for printers that don't exist and that have name patterns that look like local printers. One of the reason that the clients are hitting the /admin/ endpoint may be to somehow add these printers to our CUPS server, which is definitely not going to work.

(We've also seen signs that some Ubuntu 24.04 applications can repeatedly spam the CUPS server, probably with status requests for printers or print jobs. This may be something enabled or encouraged by cups-browsed.)

My impression is that modern Linux desktop software, things like cups-browsed included, is not really spending much time thinking about larger scale, managed Unix environments where there are a bunch of printers (or at least print queues), the 'print server' is not on your local machine and not run by you, anything random you pick up through broadcast on the local network is suspect, and so on. I broadly sympathize with this, because such environments are a small minority now, but it would be nice if client side CUPS software didn't cause problems in them.

(I suspect that cups-browsed and its friends are okay in an environment where either the 'print server' is local or it's operated by you and doesn't require authentication, there's only a few printers, everyone on the local network is friendly and if you see a printer it's definitely okay to use it, and so on. This describes a lot of Linux desktop environments, including my home desktop.)