Linux network connected devices

How to see all computers connected to a network

I am in a LAN and there are 3 Ubuntu, 2 Kubuntu, 2 Windows XP and 2 Windows 7. What commands or tools are available to see what PCs are connected to the LAN that it shows the name of the PC and the IP. Similar to tools like Angry IP that show all PCs in a LAN. Note that I do not know the IPs or names of the computers connected to the LAN. So the tool or command should look for them to.

9 Answers 9

Arp-scan works great for me too.

sudo arp-scan -l --interface=wlan0 

sudo arp-scan -l --interface=eth0 

(this last is practically identical to what Rajesh Rajendran posted; the -l standing for —localnet)

If you don’t have arp-scan (it doesn’t come with Ubuntu by default), just pull up a terminal and type:

sudo apt-get install arp-scan 

If this doesn’t work use ifconfig to get a list of interfaces and try switching eth0 to something else.

It’s not showing any IPs for me. sudo arp-scan -l —interface=wlp4s0 Interface: wlp4s0, datalink type: EN10MB (Ethernet) Starting arp-scan 1.9.5 with 256 hosts 14 packets received by filter, 0 packets dropped by kernel Ending arp-scan 1.9.5: 256 hosts scanned in 1.975 seconds (129.62 hosts/sec). 0 responded

for ip in $(seq 1 254); do ping -c 1 192.168.1.$ip>/dev/null; [ $? -eq 0 ] && echo "192.168.1.$ip UP" || : ; done 

But for a great tool, Nmap. Great for mapping networks.

I always use nmap. To scan for all devices in your network, use:

It is a great tool to know about. You may want to install nmap using:

sudo apt-get install nmap if you are using Debian or

sudo pacman -S nmap if you are using Arch.

As a possible GUI option, the best one I have seen is Angry IP as found in http://angryip.org/download/#linux

Simply download the latest DEB package and install. Then run ipscan from Dash. Here is a screenshot:

it is really good, I added all fetchers to the list columns, what helped most were hostname and macvendor, now everything connected to my wifi is more understandable, thx!

@JeffWard menu: tools/fetchers//availableFetchers//»lastItemOnTheList», then sort by macvendor, it is a short name of the hardware like D-Link

arp

Address HWtype HWaddress Flags Mask Iface iPhone-von-me.fritz.box ether 12:55:05:30:3c:df C wlp3s0 android-abcdefghijklmno ether 11:66:3f:71:04:d6 C wlp3s0 fritz.box ether 00:11:3f:46:37:c2 C wlp3s0 Blupiblu.fritz.box ether 71:88:cc:bb:dc:a6 C wlp3s0 

ip neigh

ip neigh and hosts . NO nmap / sudo required.

Building on this, you can build a Python script:

#!/usr/bin/env python """List all hosts with their IP adress of the current network.""" import os out = os.popen('ip neigh').read().splitlines() for i, line in enumerate(out, start=1): ip = line.split(' ')[0] h = os.popen('host <>'.format(ip)).read() hostname = h.split(' ')[-1] print("3>: <> (<>)".format(i, hostname.strip(), ip)) 

wget https://gist.githubusercontent.com/MartinThoma/699ae445b8a08b5afd16f7d6f5e5d0f8/raw/577fc32b57a7f9e66fdc9be60e7e498bbec7951a/neighbors.py 

If broadcast isn’t disabled on your router.

You can ping the broadcast address.

Will broadcast the ping command to every host within the 192.168.0/24 subnet.

Note: It’s probably a good idea to keep broadcasting turned off though as that’s how hackers can exploit a network using a DDOS Smurf attack. Basically, ping the broadcast address with a packet that has a spoofed destination address (ie the ip address of the victim). There’s a little more to it than that but that’s what Google is for.

Note: The same also works on Windows but you ping the actual broadcast address (not the subnet).

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How to Find What Devices are Connected to Network in Linux

Wireless networks have always been a desirable target for wannabe hackers. Wireless networks are also more vulnerable to hacking than the wired ones.

Forget hacking, do you ever wonder that someone might be leeching off your hard paid wifi network? Maybe a neighbor who once connected to your network and now uses it as his/her own?

It would be nice to check what devices are on your network. This way you can also see if there are some unwanted devices on your network.

So you might end up thinking, “how do I find what devices are connected to my network”?

I’ll show you how to do that in this quick tutorial. Not only it’s a good idea from security point of view, it is also a good little exercise if you have interest in networking.

We will use both, command line and GUI, way for finding out what devices are connected to your local network in Linux. The process is very simple and easy to use even for beginners.

Before you see any of that, let me tell you that your router should also be able to show all the connected devices. Check your gateway ip address and then type it in a browser. This is usually the browser interface for your router. Enter the username and password and you can see all the details and devices connected to the router.

If you don’t remember the router password or you don’t want to go that way, here’s what else you could do.

A. Using Linux command to find devices on the network

Step 1: Install nmap

nmap is one of the most popular network scanning tool in Linux. Use the following command to install nmap in Ubuntu based Linux distributions:

You can easily install it in other Linux distributions as well. It should be in the official software repository.

Step 2: Get IP range of the network

Now we need to know the IP address range of the network. Use the ifconfig command to find the IP address in Linux. Look for wlan0 if you are using wifi or eth0 if you are using Ethernet.

[email protected]:~$ ifconfig
wlan0 Link encap:Ethernet HWaddr 70:f1:a1:c2:f2:e9
inet addr:192.168.1.91 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::73f1:a1ef:fec2:f2e8/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:2135051 errors:0 dropped:0 overruns:0 frame:0
TX packets:2013773 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1434994913 (1.4 GB) TX bytes:636207445 (636.2 MB)

The important things are highlighted in bold. As you see my IP is 192.168.1.91 and the subnet mask is 255.255.255.0 which means that the ip address range on my network varies from 192.168.1.0 to 192.168.1.255.

You may also use ip a command to know your IP address in Ubuntu and other Linux distributions.

At the same time, I’ll recommend you to read about basic Linux networking commands for more information.

Step 3: Scan to find devices connected to your network

It is advisable to use root privileges while scanning the network for more accurate information. Use the nmap command in the following way:

[email protected]:~$ sudo nmap -sn 192.168.1.0/24
Starting Nmap 5.21 ( http://nmap.org ) at 2012-09-01 21:59 CEST

Nmap scan report for neufbox (192.168.1.1)
Host is up (0.012s latency).
MAC Address: E0:A1:D5:72:5A:5C (Unknown)
Nmap scan report for takshak-bambi (192.168.1.91)
Host is up.
Nmap scan report for android-95b23f67te05e1c8 (192.168.1.93)
Host is up (0.36s latency).

As you can see that there are three devices connected to my network. The router itself, my laptop and my Galaxy S2.

If you are wondering about why I used 24 in the above command, you should know a little about CIDR notation. It basically means that the scanning will be from 192.168.1.0 to 192.168.1.255.

B. Using GUI tool to find devices connected to network

When I first wrote this article, there was no GUI tool for this task. Then I came across a new network monitoring tool being developed for elementary OS. I suggested including a periodic device scan feature in this tool and the developer readily agreed.

So, now we have a GUI tool that does this task. It’s called Nutty (last updated in 2019). Just install this app and run it. It will periodically scan for new devices on the network and will notify you if there is a new device.

This application is only available for elementary OS, Ubuntu and hopefully, other Ubuntu based Linux distributions. You can find installation instructions on this detailed article on Nutty.

Oh, you can also log in to your router and see the devices connected to your devices. I let you figure the best way to find devices connected to your network.

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How to find Devices connected to your Network using Debian Linux

Sometimes you need to find out which devices are connected to your network. There can be several reasons for this. Maybe your Internet is running slower than usual, you notice suspicious activity that suggests someone is stealing your Wi-Fi, or you’re troubleshooting a problem. Whatever the reason, it’s a good idea to check who else is connected to your network so that appropriate action can be taken.

Nmap is a great tool to help you find devices connected to your network. It’s an open-source network discovery tool that lets you find out what other systems are on your network, what IP addresses they have, what services they offer, what operating system version they’re using, and more. It runs on almost all major operating systems, including Linux, Windows, and Mac OS.

In this article, we describe how to install and use Nmap to find devices connected to your Internet.

We use Debian 11 to explain the procedure described in this article. You can also use the same procedure for older versions of Debian.

Step 1: Open the Debian Terminal

Launch the Terminal application in your system by going into the Activities tab in the top left corner of your Debian desktop. Then in the search bar, type terminal. When the Terminal icon appears, click on it to launch it.

Step 2: Install the network scanning tool Nmap

Now in the Terminal application, run the following command as sudo to install the network scanning tool Nmap.

When prompted for the password, enter the sudo password.

The system will provide you with a y/n option to confirm the installation. Press Y to confirm and then wait for a while until the installation is completed on your system.

Step 3: Get the IP range/subnet mask of your network

Nmap needs a network ID to scan for the connected device on a specific network. So to find the network ID, we will need our IP address and the subnet mask.

Run the below command in the Terminal to find the IP address and subnet mask of your system:

The above output indicates that our system uses the IP address 192.168.72.164 /24. /24 indicates our subnet mask is 255.255.255.0. It means our network ID is 192.168.72.0 and the network range is 192.168.72.1 to 192.168.72.255.

(Note: Network ID is calculated by performing the AND operation of the IP address and the subnet mask. If you do not know how to perform AND operation, you can any online subnet calculator).

Step 4: Scan the network (LAN/WAN) for connected device(s) with Nmap

Now we have our network ID, run the Nmap scan with –sn option using the following syntax:

In our scenario, it would be:

Using Nmap with –sn option does not scan the ports, it only returns a list of live hosts:

The above results show that three active devices are connected to our network, including our system (192.168.72.164).

That’s it! We have learned how to use the Nmap tool to find the connected devices on a network. It can help you find out which unwanted users are connected to your network and using its bandwidth.

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