Scanning used ip addresses in your network

To do this, a tool named nmap can be used. This tool can easily be installed using below command:

Ubuntu

$ sudo apt install nmap -y

CentOS/RHEL/Fedora

$ sudo yum install nmap -y

Once installed, to scan your network for used IP addresses, just run below command. Please change the network address to suit your envinronment.

$ nmap -sn 192.168.0.0/24 

You will be getting output like below, and in this case you know that 5 IPs in your network has been used.