What is an Open Port? Definition & Free Checking Tools | UpGuard

Executive summary: This document provides an overview of open ports, explains how they enable network services and can become attack vectors when services are misconfigured or vulnerable, lists common ports and five free scanning/monitoring tools (Nmap, Wireshark, Angry IP Scanner, NetCat, Advanced IP Scanner), and recommends closing unused ports and continuous monitoring to reduce an organization’s attack surface.