Port scanning

Port scanning involves determining what ports are open and accessible on your target. You can liken this activity to knocking on a door to see if anyone is home. Similarly, when you perform a port scan, you are essentially checking if a port is open and listening. Apart from determining that a port is open, a port scan can help fingerprint your target.

For example, as you perform a port scan, you may find that port 80 is open and listening. Your port scanner would be able to determine which web service is running on port 80 – for example, it would return IIS or Apache, along with its respective versions.

The range of ports that are available today ranges from 0 to 65535. Ports 0 to 1023 are known as well-known ports that have been assigned by the Internet Assigned Numbers Authority (IANA). You can view the list on IANA’s website by navigating to https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml.

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