How to use Nmap to scan ports: A complete tutorial

<p>Ask any security, network or systems administrator about the top tools in their toolbox and Nmap is likely on their list. Short for Network Mapper, the versatile utility does everything from performing port scans and managing security configurations to troubleshooting network connections, documenting network environments and monitoring system uptime.</p>
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<p>Nmap offers a wide variety of features, and its additional scripting options take it to an even higher level. It gathers information, guesses OSes, provides performance information, lists system details such as MAC and IP addresses, and more. Because Nmap is open source, its support and capabilities are nearly endless.</p>
<p>One of Nmap’s most critical functions to master is port scanning. Let’s examine common ports and port scanning use cases before exploring how to use Nmap to perform various types of port scans.</p>
<section class=”section main-article-chapter” data-menu-title=”Nmap port scanning 101″>
<h2 class=”section-title”><i class=”icon” data-icon=”1″></i>Nmap port scanning 101</h2>
<p>Ports are communication endpoints through which data flows. Port numbers range from 0 to 65535:</p>
<ul class=”default-list”>
<li>Port 0 is a reserved port that is not intended for use in TCP or User Datagram Protocol (UDP) messages.</li>
<li>Ports 1 to 1023 are well-known ports used as defaults for internet protocols, defined by the Internet Assigned Numbers Authority (IANA).</li>
<li>Ports 1024 to 49151 are registered with IANA for specific applications and services.</li>
<li>Ports 49152 to 65535, known as ephemeral, dynamic or private ports, are used for temporary connections on an as-needed basis.</li>
</ul>
<p>A port scan is a network discovery technique that involves sending a series of messages, known as probes, to a device. Port scanners, such as Nmap, are applications that conduct port scans to identify which ports are open or closed.</p>
<h3>Nmap port scan use cases</h3>
<p>One of Nmap’s most helpful and widely used capabilities is scann

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