NMAP Scanner

Nmap scanner is a network scanner tool for discovery. It is a free tool that is available at this link .

Nmap uses raw IP packets to determine the nodes that are available in the network, what services or OS are running on these nodes. Please find more about the capability of namp, its working and available packages at this link .

The motivation for this experimentation is that the wifi password at our apartment is very weak; and its been almost a month that we have set that up. We would like to see if there are any unknown devices that are connected to our network. So we will be using a very basic use case of Host Scan . There is a very detailed tutorial about all the capablities of the NMAP tool at their official website at this link .

Downloading and installing

For the demonstration purpose in this document, we will be using MacOs as the platform, so the following discussion about the installation is based on MacOS.

Download : The installer is available as a .dmg image. We will be using the downloaded item from this link . Downloading an installer and installing is an easy task, and should be completed fairly easily.

Usage

Using ifconfig , we can find out IP address. This is the IP address assigned by the router locally to our MacOS machine. Suppose the IP address is 192.168.2.18 , and considering all the devices that are attached to the router are assigned similar IPs, let us find the IPs assigned to the devices using using a netmask of 192.168.2.0/24 .

Discovery : Using the command % nmap -F -O -n 192.168.2.0/24 to scan all the devices.

The -F option for fast scan.
The -O option for finding out OS detail on the nodes.