Linux Nmap network scanning tool installation and use

This paper introduces the installation and use of the Nmap network scanning tool under centos.

NMAP is a popular network scanning and sniffing tools is also a powerful tool for port scanning type safety assessment, is widely used in the security scan, NMAP is a useful online tool, also is often used in the production and development, mainly for port open view of detection and LAN information collection, etc., different Linux distributions generally also with NMAP package management tool, can also choose to go to the website to download the source code package compiled installation.

Install nmap

In case, you are unable to use nmap command, use below command to install it

 centos：yum install nmap
 ubuntu：apt-get install nmap  

Check that the installation is successful

 nmap -v

Nmap usage method

• Scan IP which common TCP port and UDP port are open

nmap 127.0.0.1 or nmap -sS -sU -p 1-65535 127.0.0.1

• Scan multiple IP addresses or subnet

nmap 127.0.0.1 172.16.6.1
nmap 172.16.6.1-100
nmap 172.16.6.0/24  

In the scan result, if the state column is open, it means the state is open; if it is filtered, it may be filtered by a firewall; if it is closed, it means the port is closed.

• Scans which hosts are alive in the subnet

nmap -n -sP 172.16.6.0/24

• Nmap route trace

namp –traceroute 8.8.8.8  

• Scans IP or subnet hosts for port

nmap -p 12598 127.0.0.1
nmap -p 12598 172.16.6.0/24

• An option that goes one step further and gives you more information about the services running on a specific host is ‘-A’.

nmap -A 127.0.0.1

• Nmap scans the operating system type using the -O option

nmap -O 12598 127.0.0.1

• For an in-depth understanding of the use of the nmap command, use it to examine the man pages

man nmap

Conclusions

nmap is one of those utilities that have so many options and capabilities, it can actually be overwhelming. As is the case with those types of utilities, you will end up using only a fraction of its capabilities to help get a specific job done. If you want to use it at its full potential, you’re in for a lot of trial and error and some hands-on experience with real networks.

So, you can read our post abour networks in this link.

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