"A port scan or portscan is a process that sends client requests to a range of server port addresses on a host, with the goal of finding an active port; this is not a nefarious process in and of itself. The majority of uses of a port scan are not attacks, but rather simple probes to determine services available on a remote machine." - Wikipedia

"Port scanning is an ideological ambiguity within the computer industry. While usually considered malicious, port scanning is often used by system administrators to diagnose problems on their own network. While most private organizations prohibit the activity, there are currently no state or federal laws that specifically address it." - The ethics and legality of port scanning.

"Court holds that plaintiff's act of conducting an unauthorized port scan and throughput test of defendant's servers does not constitute a violation of either the Georgia Computer Systems Protection Act or the Computer Fraud and Abuse Act." - VC3 vs Moulton

Lets say someone decided they wanted to port scan the entire internet. Is this port scan illegal?

  • This sounds like a question that you have researched and may want to self-answer. A suitable answer would call for more technical knowledge of the Internet than I have at my disposal. The other complicating factor of scanning the whole Internet is that you would potentially implicate the law of every country with Internet access. What is legal in the U.S. might not be legal in China or Saudi Arabia, for example. – ohwilleke Nov 8 '17 at 21:03
  • Why is "The entire Internet" important? If it is legal to scan one computer, and then another computer, why would it not be legal to continue doing that for all Internet-facing computers? Alternatively, if it is not legal to scan a computer for some reason, then we can stop right there without considering "the entire Internet." – Brandin Nov 8 '17 at 21:54
  • Additionally, "the entire Internet" is inherently multijurisdictional, so there's no clear answer. – Stackstuck Nov 9 '17 at 8:53
  • Usually for situations like this that deal with the internet. The originating country where a packet is sent FROM is the jurisdiction in which the law would be enforced. So for this instance, assume it is the United States. – Digital fire Nov 9 '17 at 15:04
  • @DigitalFire Then you should say "Is port scanning legal in the US" or "Can I port scan all computers in the US" or something to that effect. Delete "entire Internet." – Brandin Nov 11 '17 at 11:17

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