They arise quite frequently if you're running non-standard network services.
I have a service that I don't want to run as a root user, even temporarily, and therefore it needs to bind to a non-privileged port. In principle, another service could bind to the same port if it goes down.
> However, do you agree that removing the notion of privileged ports...
I'm not convinced people are suggesting only removing the privileged port restriction, but rather replacing it with something more flexible.
Just being able to lock ports down to a uid would suffice for many use cases and could work the same way as the legacy system by default, with ports <1024 reserved for root and other ports not reserved. Then, e.g.
# echo "8080 <MYUID>" > /proc/sys/net/ipv4/conf/all/portsec/register
and no-one but me can bind to 8080 on any interface.
Of course there are more extensive proposed solutions, but this would solve every problem I've ever had with binding to a privileged (or not) port.
> There is also this which lets you do something like what Windows Firewall does and use iptables to restrict which uid/gids can do certain types of IP communication
That's only a solution if I can bind to the port in the first place, and in a way that doesn't open me up to having my port hijacked by some other process, like on Windows.
