That's none of the business of my ISP to care about. If a botnet abuses my connection to send excessive traffic, that's going to be limited by the bandwidth lim

That's none of the business of my ISP to care about. If a botnet abuses my connection to send excessive traffic, that's going to be limited by the bandwidth limit I'm paying for. Restricting ports also doesn't mitigate it, as a port scanner can easily find out I'm running this or that vulnerable server software on a non-standard port. It's none of the ISP's business to restrict the ports I should be using.