Detecting the Operating System manually through open ports

It's Friday evening. You got no plans for the weekend and you're sitting at your machine with a cup containing caffeine by your side.
You hate that motherfucker in your class who gets everyone's attention as he always pretends being a hacker by using the phishing method to store and change people's Facebook's passwords. He hacked the college Wi-Fi without having any skills. You know he's just a script kiddie.
Time to check what he really is!

Your evil hands fire up BackBox!

:~$ su
Password : **********

NOTE : This article is intended for educational purposes only. Scanning someone's computer without his/her permission is a crime. I'll not be responsible for anything the reader does.

Before planning the strategy to enter his system. You need to scan his system to find the open ports. Ports are the endpoints which connect other computers or peripheral devices. Different services run on different ports.

You run your favorite network scanning tool, 'nmap' to scan all the open ports in his system.
First, let's check which Operating System he uses using the (-O) switch.

:~# nmap -O 192.168.1.3

Bash replies with this output :

Here, the nmap tool scans the system for open ports and returns with the Operating System installed on it.

The OSScan is not sure which OS it exactly is. But it gives us the hint of a Microsoft Windows based device.

In future, you will need to work with network scanning tools. Guessing the Operating System manually based on open ports is an essential skill to learn.

Here, I'm giving a list which will help you in determining the OS in future.

Port                Service/OS

139                 Windows 95/98

135,139,445   Windows

3389               Remote Desktop Protocol (RDP) - WIndows

TCP 111         Portmapper - Unix/Linux

TCP 22           SSH - Unix/Linux

TCP 2049       NFS - Unix/Linux

TCP 512-514  Berkley R - Unix/Linux

3277x +         Solaris Linux

Now have a look in the above screenshot. Port 135, 139 and 445 are open. So, it's now confirmed that he uses a Windows based system.
*Windows OS confirmed!*
*Script kiddie confirmed!*