How to Find a List of All Used IP Addresses on a Network

By Keith Perry

Identifying all of the used IP addresses on a network is useful when performing maintenance or administration changes. This is also very useful for detecting when a new device is attached to the network. Many companies perform a nightly scan of the network to check which IP addresses are in use and perform a comparison with a previous scan to identify potential security threats. Nmap is an open source scanner used by professionals and hobbyists to perform various network scanning activities. It is perfect for this activity.

Things You'll Need

  • Windows computer
  • Nmap scanner software

Step 1

Download the "latest stable self-installer" version of Nmap for your computer (see Resources).

Step 2

Install Nmap on your machine by double-clicking on the Nmap setup file. Follow the instructions to install it on your local drive in the default directory.

Step 3

Click the "Start" button on the Windows menu bar, type "cmd" in the text box and press "Enter" to open a command window.

Step 4

Type the following command: nmap -sP 192.168.1.0/24. Press "Enter".

Step 5

Nmap will scan the entire range of IP addresses, starting with 192.168. A list of all IP addresses in use will show with the text "host is up" below the IP address.

Tips & Warnings

  • When scanning a slow network adjust the scanning speed to ensure you do not cause the network to fail.
  • Always obtain permission from the network owner before performing a scan.