Find devices on a network in Linux

Finding a device that’s connected to a network on Linux is easy with an open source tool named nmap.

What is nmap?

nmap is a utility for network discovery and security auditing. It’s designed to rapidly scan large networks.

Install nmap

nmap is available through most popular package managers.

For Debian-based distributions:

1

sudo apt install nmap

For MacOS:

1

brew install nmap

Using nmap

Firstly, grab your IP address using ifconfig

1

ifconfig

the output will contain an IP.

1

inet 192.168.1.91 netmask 0xffffff00 broadcast 192.168.1.255

nmap is simple to use - simply run the command like the example below:

1

sudo nmap -sn 192.168.1.0/24

The /24 is CIDR notation. It’s instructing nmap to scan all ip addresses between 192.168.1.0 and 192.168.1.255.

The -sn option is a portless scan of the IP address range.

Output:

1
2
3

Nmap scan report for 192.168.1.20
Host is up (0.012s latency).
MAC Address: 00:11:32:C2:7B:96 (Synology Incorporated)

In my case, I was looking for the IP address of my Synology NAS.