How To Scan All Ports With NMap

How To Scan All Ports With NMap

Open ports might be dangerous for your online security even though they are required for all internet communication. To assist you decide which ports should be closed, you need an open-source port inspection programme like Nmap. You may learn more about the effectiveness of your security configuration and firewall with this tool.

This post will demonstrate how to use the Nmap application to scan all ports. Additionally, we’ll define port scanning and discuss its benefits.

Nmap All Ports Scanning

A network programme called Nmap, sometimes known as Network Mapper, is used to scan hosts, operating systems, and services within a computer network. Although this application was initially created for Linux, it is now compatible with Windows, macOS, and BSD. Port scanning, host discovery, version detection, network inventory, TCP or IP stack fingerprinting, etc. are some of the most crucial Nmap functions. We’ll concentrate on checking for open ports today.

You may find out which network ports are open and closed by using the method known as port scanning. A port is set to accept packets, which are collections of data transferred through computer networks, if it is open. Simply explained, information is sent and received through open ports. You can find out which ports are open and potentially exposing sensitive data on your network once you have scanned all of your ports.

Nmap can let you scan each of the more than 65,000 ports. The scanning modes offered by this programme include discovery, default, aggressive, safe, external, malware, version, dos, exploit, broadcast, and more. You may get various outcomes based on the scanning method you use. For instance, while scanning all ports with the safe scan, the target won’t crash. You must employ an aggressive scan if you wish to identify systemic weaknesses.

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You can use Nmap to scan all ports, a specific port, or a group of ports. Even a command to scan the top 100 ports is available. You must use the Nmap command “nmap -p-” to scan all ports, which covers ports 0 through 65,535.

“nmap -p 22” is the command to enter if you only want to scan one port. You would need to enter the command “nmap -p 1-100” in the Nmap window in order to scan a number of ports. Finally, “nmap -F” is the command you use when scanning the 100 most popular ports.

You might have noticed that all ports and the 100 most popular ports have nearly identical commands; the only distinction is the first letter (“F” and “p”). You must therefore use caution while putting the code into the dialogue box.

The simplest method for using Nmap to scan all ports is to start the application, type the necessary command, and then wait for the scan to be finished. As this programme needs to scan over 65,000 ports, keep in mind that it will take Nmap a while to scan every port—roughly 10 to 15 minutes for the full scanning procedure. You’ll need a target to run the scan on. Your target can be a hostname, an IP address, a network range, etc.

Nmap must be downloaded first. For particular operating systems, such as Windows, Linux (RPM), macOS, and any other OS, there are many versions of Nmap available. Keep in mind that you must have an administrator account in order to use Nmap for any operation. You must first know your hostname in order to search for all open ports on your network. Here is how to accomplish it:

  • In the same motion, press the “Windows” and “R” keys. By doing this, the “Run” dialogue will open.
  • After typing “cmd” in the box, press “OK.”
  • In the window of the Command Prompt, type “ipconfig /all”.
  • Copy your hostname from “Windows IP Configuration,” which is located there.
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You can exit this window and launch Nmap after you know your hostname. What you should do next is as follows:

  • Into the “Target” box, paste the hostname.
  • To scan all ports, type “nmap -p-” next to “Command.”
  • In the program’s upper right corner, click the “Scan” button.

Nmap will provide a list of ports with a variety of statuses after the scan is finished. Ports can be filtered, unfiltered, open/filtered, closed/filtered, in addition to open and closed.

What Other Types of Scans Can Nmap Perform?

There are various sorts of scan techniques, and they can even be put together to accomplish a particular objective. Some of these require root access on Unix systems, making them only accessible to experts.

Keep in mind that you can only apply one technique at once. There are some exceptions, such as combining TCP and SCTP scans with UDP and SCTP scans. By default, Nmap employs the SYN scan, sometimes referred to as half-open scanning. This kind of scan can quickly and efficiently scan thousands of ports. The command “nmap -sT” is necessary for the SYN scan. Only Nmap receives a SYN message after the scan is finished.

Additionally, you have the ability to select scans that use TCP connect, UDP port scanning, and other methods. A lot of people also use ping scans. They are the most straightforward port scans, which seem as ICMP (internet control message protocol) requests. We also have XMAS scans, which are referred to as the “sneakiest” port scanning techniques because firewalls hardly ever prevent them.

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Finding open ports is the primary goal of Nmap and other kinds of port checkers. An open port can be compared to an open window, notwithstanding how valuable it is. It is constantly vulnerable to cyberattacks.

HTTP (80), Proxy (3128), FTP (21), SSH (22), DNS (53), SMTP (25), DHCP (67, 68), SFTP (115), IMAP (143), LPD (515), rsync (873), etc. are some of the most used open ports.

Closed ports are accessible, contrary to what some people may believe. Closed ports can receive probe packets from Nmap, but they won’t respond to them. In other words, closed ports will ignore packets if you can transmit them to them.

A closed port is referred to as a filtered port if a firewall is used to protect it. A packet sent to a filtered post will be able to get there. Firewall protection will merely prevent it. You may occasionally encounter unfiltered ports, which are ports that Nmap cannot distinguish between being open or closed.

Restore Network Security and Stability With Nmap

Nmap may at first appear difficult to use, but even the most basic commands don’t require a competent IT specialist to execute them. Nmap allows you to scan all ports, a single port, a group of ports, or the 100 most popular ports. Nmap will inform you of the open ports if you want to scan every port, which will reveal whether they are susceptible to hacker attacks.

Have you ever attempted to scan all ports with Nmap? What kind of scanning system did you employ? What number of open ports did the programme discover? Comment below with your thoughts and let us know.

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