Subnet scanning with Nmap

If you are ever wondering which ip addresses on your network are currently being used, you can use nmap to find out.

For example to scan an entire class C subnet you can use the following command:

‘nmap -sP -R 192.168.1.0/24 |grep up’

This will produce a list of ip addresses which are currently being used.

You can also use this command to find a list of inactive ip addresses when you are looking to add devices to your network:

‘nmap -sP -R 192.168.1.0/24 |grep down’