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This article mainly introduces how to use the nmap command in Linux to determine whether a port is open or not, which has a certain reference value. Interested friends can refer to it. I hope you can learn a lot after reading this article.

How do I use the nmap command to see if a port is open on a remote Linux system?

Nmap ("Network Mapper") is an open source tool for network exploration and security auditing, designed to scan large-scale networks quickly, although it also works for a single host.

In a novel way, nmap uses naked IP packets to determine whether hosts on the network are reachable, what services they are providing (application name and version number), the operating system they are running (version of the system), what filtering software or firewalls they are using, and other additional features.

Although nmap is often used for security audits, many system and network administrators find it equally useful in routine tasks such as listing network assets, managing service upgrade plans, and monitoring hosts or services for proper operation.

General syntax for nmap:

$nmap [- options] [HostName or IP] [- p] [PortNumber]

If the port is open, you will get the following output:

# nmap 192.168.1.8-p 22 Starting Nmap 7.70 (https://nmap.org) at 2019-03-16 03:37 IST Nmap scan report for 192.168.1.8 Host is up (0.00031s latency). PORT STATE SERVICE 22/tcp open ssh Nmap done: 1 IP address (1 host up) scanned in 13.06 seconds

If the port is not open, you will get results similar to the following:

# nmap 192.168.1.8-p 80Starting Nmap 7.70 (https://nmap.org) at 2019-03-16 04:30 ISTNmap scan report for 192.168.1.8Host is up (0.00036s latency). PORT STATE SERVICE80/tcp closed http Nmap done: 1 IP address (1 host up) scanned in 13.07 seconds Thank you for reading this article carefully. I hope the article "how to use the nmap command to determine whether a port is open in Linux" shared by the editor will be helpful to everyone. At the same time, I also hope that you will support us and pay attention to the industry information channel. More related knowledge is waiting for you to learn!

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