Illegal nmap port scanning
Referring to a previous post about nmap port scanning an isp ( forums.remote-exploit.org/archive/index.php/t-7364.html ), where thePrez98 said:
I'm curious why the act of port scanning is illegal. Doesn't nmap use the same mechanisms an any web browser establishing a TCP connection, only in a different manner (ie couldn't you point a browser sequentially at every ip and monitor the response ) ? Do you not have permission and authorization to point a web these same ip s ? In other words, what makes nmap different?
... 'You clearly do not own "more than about 4-5 domains" therefore you have admitted to scanning domains to which you do not have permission or authorization.' ...
Also, is the illegality a law or is it a violation of an agreement one signs with the isp?
I'm partially playing devil's advocate, though I'm genuinely curious about the definition of public vs private space on the internet.