Many times i see people asking this question in diferent forums ans mailing list…
Here i have tried to answer to this… correct me if i am wrong…
Under the Indian Information Technology Act, 2000, the act of port scanning does not amount to hacking.

which is defined as:

“Whoever with the intent to cause or knowing that he is likely to cause wrongful loss or damage to the public or any person destroys or deletes or alters any information residing in a computer resource or diminishes its value or utility or affects it injuriously by any means, commits hacking.”

The essential elements of hacking are

1. Intention or Knowledge
2. Wrongful Loss to Public or Person
3. Deletion / Alteration / Destruction or
4. Diminishes Value or Utility

of information iesiding in a computer resource

Port Scanning will satisfy the first requirement of Knowledge or Intention.

But the second essential is not met, as port scanning does not necessarily cause any wrongful loss. E.g. if a network administrator, scans his own network for security reasons, then he will not intend to create any wrongful loss.

Also, all the other elements of hacking are also not invoked as port scanning merely scans the crust of the network without affecting any information resource residing within it.

Thus Port Scanning definitely does not attract the offence of ‘hacking’, unless it is used by a cracker, with the intention to crack the system, and in conjunction with any other tool that actually changes any information that resides in the computer.

so enjoy and explore the knowledge.

** Please Note that Most ISP’s internet starter packs also include a printed manual. It clearly mentions that they dont expect you to not indulge in anything like portscanning, as the traffic goes from the ISP’s server. **

— Source : Indian Information Technology Act, 2000 —
—- i used the word “hacking/hacker” to go on with the definition of indian cyber law. Though i strongly believe that there is a difference between hackers and crackers.