How to find all the used IP addresses on a network

Question

In my work there is a lot of computer and I want make a joke. I can close computer over the network but finding IP addresses is hard to me.

How can I easily find all online IP adresses from 192.168.1.aa to 192.168.1.zz?

Answer 1

Generally, nmap is useful to quickly scan networks.

To install nmap, entersudo apt-get install nmap.

Once it is installed, enter nmap -sP 192.168.1.0/24.

This will show you which hosts responded to ping requests on the network between 192.168.1.0 and 192.168.1.255.

Answer 2

If all the computers in your network are Ubuntu or any other distribution that makes use of avahi-daemon (DNS-SD), you can get a detailed list of them (with hostname and IP address) by doing:

avahi-browse -rt _workstation._tcp

If you want to know all the IP addresses used in your network, you can use arp-scan:

sudo arp-scan 192.168.1.0/24

As it is not installed by default, you'll have to install it with sudo apt-get install arp-scan. arp-scan send ARP packets to the local network and displays the responses received, so it shows even firewalled hosts (that block traffic based on IP packets).