Finding LAN Devices

Finding Devices on Your Local Network in Linux

Sometimes you need to find:

• your Raspberry Pi
• another computer on the LAN
• a phone
• a smart TV
• a server
• an unknown device connected to your router

Linux provides several useful commands for exploring your local network.

Viewing Network Interfaces

The first thing you usually want to know is:

• your IP address
• your subnet
• your network interface name

Use:

ip addr

Example output:

2: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP>
    inet 192.168.1.23/24

This tells us:

• interface name: wlan0
• local IP address: 192.168.1.23
• subnet mask: /24

A /24 subnet usually means the network range is:

192.168.1.0/24

Understanding the Subnet

If your machine has:

192.168.1.23/24

then:

• network address: 192.168.1.0
• possible devices: 192.168.1.1 → 192.168.1.254

Usually:

• .1 is the router
• other devices receive addresses dynamically via DHCP

Viewing Known Devices with ip neigh

Linux maintains a neighbor table containing devices your machine has recently communicated with.

View it using:

ip neigh

Example:

192.168.1.1 dev wlan0 lladdr 34:60:f9:aa:bb:cc REACHABLE
192.168.1.5 dev wlan0 lladdr 11:22:33:44:55:66 STALE

Explanation:

• 192.168.1.1 → device IP address
• wlan0 → network interface
• lladdr → MAC address
• REACHABLE → device recently responded
• STALE → entry exists but has not been contacted recently

This command is useful for quickly seeing devices already known to the system.

Using arp -a

Older systems often use:

arp -a

Example:

router (192.168.1.1) at 34:60:f9:aa:bb:cc [ether] on wlan0

This shows similar information to ip neigh.

ip neigh is considered the modern replacement.

Scanning the Entire Network with nmap

nmap is one of the most useful network scanning tools available.

Install it:

Arch / Artix

sudo pacman -S nmap

Debian / Ubuntu

sudo apt install nmap

Ping Scan with nmap -sn

To discover active devices on your network:

nmap -sn 192.168.1.0/24

Explanation:

• -sn means:
  • host discovery only
  • no port scanning

Sometimes nmap can also identify the device vendor:

Raspberry Pi USB Gadget Networking

If SSH over USB is enabled on a Raspberry Pi, plugging it into a Linux computer may create a USB network interface.

Check interfaces:

ip addr

You may see:

• usb0
• enx...

Typical addresses:

Connect using:

ssh pi@192.168.7.2

or:

ssh username@raspberrypi.local

Discovering .local Hostnames with Avahi

Linux systems can use mDNS (multicast DNS) for hostname discovery.

Install:

Arch / Artix

sudo pacman -S avahi nss-mdns

Start the service:

sudo systemctl enable --now avahi-daemon

Browse devices:

avahi-browse -at

This may show:

• Raspberry Pis
• printers
• Linux machines
• smart devices

Useful One-Liners

Show only IPv4 addresses

ip -4 addr

Show routing table

ip route

View active listening ports

ss -tulpn

Ping a device

ping 192.168.1.1