Yeah our school basically had one big LAN (everything got a publicly routable IPv4 address, but nothing within the university was firewalled from anything else). There were networked printers though in the computer labs, some of these labs being on the first floor of the dorms. If you needed to print slides before class (and professors always posted the slides only like an hour before class), you had to go to the lab, hit print, and wait 15 minutes for the printers to get to your job in the queue and the staff to actually fetch it and lay it out. Definitely added to the time it took to get to class.

Since I was already accessing my dorm computer via Samba in the labs (I know, dumb idea in hindsight, even with a password, but this was 2004), I decided to figure out a way to print directly from my room and then just grab it on the way to class. Long story short I ran a port scan on the computer lab to find the printer IPs and had my network port turned off within minutes (I had the IPs though!). Ended up having to go to some office and explain what I was doing. Got turned back on a few days later.

The upside was that I eventually was able to print from my room as long as I converted whatever it was to postscript first. The downside was that I didn't need to know the printer IPs after all (the university's unix server already had the printers setup... just piped it through ssh to it).

Now I'm curious. It's not safe to run this at home, on any sort of paid hosting, on a university network, where is it safe to run this program?

If you work for an ISP?

If you ask the University nicely?

On a colocation facility that you own using a net port that you pay for yourself?

As soon as you expose someone downstream to stuff like this you're asking for being disconnected. If you ask your University nicely they'll likely refuse unless you state a goal you wish to achieve.

If using a script to download documents qualifies as hacking then hitting all of the internet with a portscanner is likely going to get you network administrator attention of the entirely wrong kind. And that's because they in turn will get some flak from the outside world.