Port scanner is an application that randomly searches for vulnerable areas of the computers that are connected on a network. When you use the Internet, port scanners might try to infect through known vulnerabilities on your Mac. The Vulnerability Protection feature of Norton Security for Mac provided by Symantec Endpoint Protection Small Business Edition cloud (SEP SBE.Cloud) monitors your Mac for port scans and blocks the connection from unauthorized or unknown computers.
Port scans are also used for legitimate purposes. For example, network administrators perform port scans to find and solve any potential problem in your Mac. You can adjust the sensitivity of Vulnerability Protection against the port scan.
Your Norton product notifies you each time it blocks a port scan. The number of notifications varies based on the sensitivity level that you configure for port scans. For example, if you configure the Most secure option, your Norton product displays more notifications. Norton port scan detection does not work when the built-in macOS firewall is turned on.