Network Discovery & Security Auditing with Nmap

Hey Everyone, Today we are going to learn about Nmap, One of the best tool in the world of Penetration Testing.I will share top 15 commands of Nmap here(added some screenshots too).
Enjoy the Network Scanning…!!

What is Nmap?
Nmap (“Network Mapper”) is a free and open source (license) utility for network discovery and security auditing. Many systems and network administrators also find it useful for tasks such as network inventory, managing service upgrade schedules, and monitoring host or service uptime. Nmap uses raw IP packets in novel ways to determine what hosts are available on the network, what services (application name and version) those hosts are offering, what operating systems (and OS versions) they are running, what type of packet filters/firewalls are in use, and dozens of other characteristics. It was designed to rapidly scan large networks, but works fine against single hosts. Nmap runs on all major computer operating systems, and official binary packages are available for Linux, Windows, and Mac OS X.
Top 15 Commands of nmap:
Target machine:metasploitable 2(192.168.138.133)
1.Single IP scan
#nmap 192.168.138.133

2.Scan Multiple IP
#nmap 192.168.138.133,134,135
3.Scan a Range of IP
#nmap 192.168.138.0-200
4.Identify the Operating System of a host
#nmap -O 192.168.138.133

5. Exclude IP/Hosts/Networks From Nmap Scan
#nmap 192.168.138.0/24 –exclude 192.168.138.132
#nmap 192.168.138.0/24 –exclude 192.168.138.124 192.168.138.125
# nmap 192.168.138.0/24 –exclude 192.168.138.125,126,127
6.Scan For Specific Ports
#nmap -p 80 192.168.138.133
#nmap -p 80,443 192.168.138.133
#nmap -p 80-200 192.168.138.133

7.Scan TCP and UDP port
# nmap -sS -sU -PN 192.168.138.133
8.Display the Reason a Port is in a Particular State
#nmap –reason 192.168.138.133
It display the Reason why Nmap thinks that a port is in a particular state.

9.Show Only Open Ports
#nmap –open 192.168.138.133
10.Service Version Detection
#nmap -sV 192.168.138.133

11.Firewall Detection
#nmap -sA 192.168.138.133
12. Scan a Firewall For Security Vulnerabilities
TCP Null Scan: TCP flag header is 0
# nmap -sN 192.168.138.133
TCP Fin Scan :
# nmap -sF 192.168.138.133
TCP Xmas Scan :
#nmap -sX 192.168.138.133
* Set the FIN, PSH and URG flags.
13.Stealthy Scan
TCP SYN Scan : It never open full TCP Connections
#nmap -sS 192.168.138.133
14.Disable Host Discovery (No Ping)
#nmap -Pn 192.168.138.133
15.Vulnerability scan
#nmap –script vuln 192.168.138.133
This scan is very useful as it discloses the vulnerability of the target.