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Intrusion Detection FAQ: Can I take legal actions against port scanning?

Port scanning is like ringing the doorbell to see whether someone's at home. The police usually can't do anything about it. They have to wait until a crime is committed. For example, in Germany and Singapore, port scanning cannot be prosecuted. However, consult your local lawyer to see if this is true in your country. Sometimes, if a computer system is affected too much by a port scan, one can argue that the port scan was, in fact, a denial-of-service (DoS) attack, which is usually an offense.