What is a port scan?

A port scan is a check of which network ports are open on a machine or a range of machines, to find out which services are running, such as web, file sharing or remote desktop. Administrators scan their own networks for inventory. Attackers scan to find a way in, and after they get in they scan again from the inside to find the next target. Scans from the internet hit every public address all day and are mostly noise. A scan that starts from a computer inside your network is different, and is often one of the first visible signs of an intruder. NetSenX detects scanning on every plan.

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