Hello, after a long time without writing, I finally found the time.

And in another tutorial, we’ll learn how discover open ports or closed on a server, computer …

nmap

For this task, we use the command nmap .

According to nmap’s own description, the application is:

Nmap (“Network Mapper”) is an open source tool for network exploration and security auditing. It was designed to track (Scan) large networks quickly yet works well with a single host (host). Nmap uses raw IP packets in (raw) on new ways to determine what hosts (hosts) are available on the net …

For more details you can find in http://nmap.org/ . I like to use nmap, but it does not mean that this is the only way to accomplish this task.

Listing the main server ports

The simplest of commands, just run nmap to the server that you want to investigate

nmap test.com

Listing the main server ports in more detail

nmap -s test.com

Verifying several machines on the network

Very useful for network administrators

Check certain ips

nmap 192.168.254.1 192.168.254.2 192.168.254.3

Verifying a track (one range) of IP’s

 nmap 192.168.254.1-10

 Verifying a range using wildcard 
nmap 192.168.254.*

nmap -p [port] test.com

nmap -p 80-400 test.com