How to find devices connected to the network using Debian

Sometimes you need to find out which device is connected to your network. It could be for a number of reasons such as slower internet speed than usual, you notice some suspicious activity (someone is stealing your WiFi) or when troubleshooting.

In this article, TipsMake.com will describe how to install and use Nmap to find devices connected to your network.

Step 1: Open the Debian Terminal

Launch the Terminal application in the system by going to the Activities tab in the top left corner of the Debian screen. Then in the search bar, type terminal. When the Terminal icon appears, click it to launch the tool.

Step 2: Install the Nmap network scanning tool

Now in the Terminal application, run the following command as sudo to install the Nmap network scanning tool.

$ sudo apt-get install nmap

When prompted for a password, enter the sudo password.

The system will give you the Y / N option to confirm the installation. Click Yto confirm and then wait for a while until the installation is complete on the system.

Step 3: Get the IP range / subnet mask of the network

Nmap needs a network ID to scan connected devices on a specific network. So, to find the network ID, you will need the IP address and subnet mask.

Run the following command in Terminal to find the system's IP address and subnet mask:

$ ip a

The above output indicates that the system is using IP address 192.168.72.164 / 24. / 24 indicates the subnet mas to be 255.255.255.0. That means the network ID is 192.168.72.0 and the network range is from 192.168.72.1 to 192.168.72.255.

Step 4: Scan the network for device (s) connected using Nmap

Now you have the network ID. Run the Nmap scan with the -sn option with the following syntax:

$ nmap –sn 

In this example, the command would be:

$ nmap -sn 192.168.72.0/24

Using the Nmap option with the -sn option does not scan ports, it only returns a list of live hosts:

The above results show that there are 3 devices currently connected on the network.