BTW the same thing applies to mooching wifi, even hacking AFAIK isn't illegal. And as far as halacha is concerned, it's definitely not gezel, however if you are hogging bandwidth to the point that you are noticeably degrading the speed of other users then you may fall under the category of mazik.
I know someone who got a heter from a competant rav to hack a wifi and use it (internet issue aside). YLORMV
How about if I have an allocated amount of bandwidth, and you cause me to go over by using it, resulting in me having to pay for the extra?
