What is Nmap? A Deep Look at Basic

Hi Everybody! If you want to hack anything the first thing you should know is the configuration of that thing i.e. what is the operating system running on the server, closed and open ports extra. To detect the operating system and ports you should implement nmapscanning on the server. In this article I am going to say you what is Nmap and how it is used, that too in detail.

What is it?

Nmapstands for Network Mapping simply called as network mapper. It was developed by Fyodor. Either commercially or open source it is the best mapping technique available in the market. It is everywhere. Nmap became this much popular because it has more than fifteen scanning techniques. As it was open source it goes under constant updating.

Nmapis used by security professionals to find the vulnerability of their website. Hackers also use to knock the backdoor of the servers. So many members say that Nmap is a bad program that helps hackers to break the backdoor of the networks but they also should have it to discover that vulnerability. It is used in both the ways to hack and to predict the vulnerability.

If you performed the wrong scan of nmapon any system it will crash the applications running on the system and DOS (Denial of Service) attack will also be taken place. So be careful.

If you use plain nmap scan it will handle nicely. The default scans can do no harm. While performing scans your scan can be detected and blocked by the firewalls, I will also say how to reduce the detection of your scan in coming articles.

How does it work?

There is a total of 65535 ports are there in a system more precisely doors. The nmapscan will go to each port and check whether the port is locked or unlocked i.e. closed or open. If any door left open it informs you of the port number.

While you are performing nmapscan nmapthe station will send the requests to the target server and the replies given by the server will be three types

Ports are closed
Ports are open
No reply
The third option is the station won’t get any reply from the server then nmapstates that the particular port is filtered. This happens due to the firewall and you can also bypass the firewall using some techniques which will be taught in the coming articles.

There are many more advanced options in nmapother than port scanning like application version identification, operating system fingerprinting and ideal scans.

The default nmapthe scan makes over 1500 queries with the target device, there 15 different scan methods and 15 different scan techniques created every time.

The best thing in nmapis you will have complete control over the scan you can send one packet or thousands of packets. You can also determine the delay between the queries.

Scanning performance on Linux and Windows

The best performance is unleashed on Linux and this is the only answer you will get from everyone. In windows, there will be frequent updates and changes so that at any time nmapmy stop working as it took with Windows XP service pack 2 and if an update is available for nmapit is first given to Linux and then imported to windows but now windows are completely capable for nmap. You can download the software from Nmap download. This link for both Linux and Windows. In Linux c++ compiler should be installed or you will get errors.

You can directly run the installer in windows that will install nmapbut in Linux after downloading nmap.tar.bz2 copy to the desktop and run single line command to decompress and install it.

Now you will see all the files that extracted to nmapfolder

Now change the current directory to nmap

now configure your nmap

Now you can see the completion of the configuration

Now type

in the terminal to compile all the files to a single file

You will be getting errors while installing regarding GTK this is because if you have GTKyou can perform nmapwith Graphical User Interface. You no need to install it but if you want GUI you can install it.

Now install nmapwith the command

Go to the home directory

To find the IP address of your own system you can use the command

To perform default scan use

for example

it shows the open and filtered ports

In windows, you can run commands for IP detection

and to scan