How to Find Unused IP Addresses in Network

Sometimes you may need to find unused IP addresses in your network. You can easily do this using nmap utility tool. Here is how to find unused IP addresses in your network. NMAP tool is available for Windows & Linux. It uses ARP (Address Resolution Protocol) to determine if IP address is free or not. This approach is more reliable than ping scans, port scan, broadcast pings that may not work due to firewall and OS policies.

How to Find Unused IP Addresses in Network

Here are the steps to find unused IP addresses in your Network.

1. Install NMAP

Open terminal and run the following command to install NMAP.

$ sudo apt-get install nmap

2. Find Unused Ports

Run the following command to find unused ports on your network. Here is an example to find unused ports in range 192.168.1.1-192.168.1.255

$ sudo nmap -sP 192.168.1.*
OR
$ sudo nmap -sn 192.168.1.0/24

That’s it. As you can see it is very easy to find unused ports on your network using NMAP command.

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