Nmap is a tool for network exploration and many times used for security audit. It sends raw packets on target PC and then it determines many features of target PC such as MAC address, Open Ports, OS Detection etc.
Below is simple use of nmap command in linux. Before that you need to install the tool. The minimum installation does not install nmap tool.
# yum install nmap -y
Now let us see the usage,
To get list of open ports on target PC, you can use
[root@station5 ~]# nmap 10.0.0.1 Starting Nmap 6.40 ( http://nmap.org ) at 2016-10-02 21:57 IST Nmap scan report for 10.0.0.1 Host is up (0.00022s latency). Not shown: 997 closed ports PORT STATE SERVICE 21/tcp open ftp 22/tcp open ssh 80/tcp open http MAC Address: F2:1F:48:AC:FC:DB (Unknown) Nmap done: 1 IP address (1 host up) scanned in 0.10 seconds [root@station5 ~]#
For OS Detection of target PC, you can use -O option.
[root@station5 ~]# nmap -O 10.0.0.254 Starting Nmap 6.40 ( http://nmap.org ) at 2016-10-02 21:59 IST Nmap scan report for 10.0.0.254 Host is up (0.0014s latency). Not shown: 998 closed ports PORT STATE SERVICE 21/tcp open ftp 80/tcp open http MAC Address: 40:4A:03:4B:1B:53 (ZyXEL Communications) Device type: broadband router Running: Telewell embedded OS CPE: cpe:/h:telewell:tw-ea501 OS details: Telewell TW-EA501 ADSL modem Network Distance: 1 hop OS detection performed. Please report any incorrect results at http://nmap.org/submit/ . Nmap done: 1 IP address (1 host up) scanned in 1.39 seconds [root@station5 ~]#