This reminds me of a program I once wrote when I first learnt SQL, a sort of randomizing port scanner that would just try random combinations of hosts and ports

This reminds me of a program I once wrote when I first learnt SQL, a sort of randomizing port scanner that would just try random combinations of hosts and ports and store its results into a database. Later, I added stuff like attempting AXFR zone transfers, which was interesting, and I came across some university that apparently had no firewalls in place whatsoever. I found a few devices with open telnet ports, mostly printers. I remember clearly the thrill I felt when I realized I could make this printer refuse any print jobs or remove jobs from its queue. I also found a few devices I had no clue about. The latter where the ones I found most fascinating, although I never took the trouble to research what those devices might have been. I suspect, though, that nowadays there must be a whole lot more of such devices around, with IoT and all that. (My scanner never looked at VNC or RDP, though... This site makes me wish I had thought of that.)