While there may not be a law directly addressing portscan/reconnaissance activities. It is generally forbidden by the your ISP's TOS/AUP. There are a growing number of bastards like myself that take great delight in finding people doing such activities and reporting them to their respective ISP's and having their accounts canceled for doing it.
Basically, you have no good reason to be conducting portscans against networks that you are not authorized to do so.




