Finding network devices linux

How can I find available network interfaces?

This is in regard to linux, but if anyone knows of a general *nix method that would be good. I booted a system yesterday with an ethernet cable plugged in. «NetworkManager» is not installed, so once it started I went to look for the name of the ethernet interface with ifconfig to start a DHCP client manually, but it did not show anything other than lo . The NIC was listed via lspci , and the appropriate kernel driver was loaded. The system normally uses wifi, and I could remember the interface name for that was wlan0 . When I tried ifconfig wlan0 up , wlan0 appeared. But the only ethernet interface names I could remember were eth[N] and em[N] — neither of which worked. This document refers to «predictable interface names» but does not do a good job of explaining what they might be in simple terms. It does refer to a piece of source code which implies the name in this case might be deduced from the the PCI bus and slot numbers, which seems like an unnecessarily complicated hassle. Other searching around led me to believe that this might be determined by systemd in conjunction with udev , but there are almost 100 files in /usr/lib/udev/rules.d and spending an hour trying to determine where (and if) there’s a systemd config file for this also seems ridiculous. It would also be nice to know for certain that they are available, not just how they might be named if they are, so I can rule out hardware problems, etc. Isn’t there a simple way to find the names of available network interfaces on linux?

In the question you state that you used ip link but then you accept an answer that suggests ip link show which does the exactly same thing. Why?

The manual pages for iproute2 are quite good nowadays, I guess you’re using and older version of the package.

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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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Find Devices Connected to Your Network with nmap on Ubuntu 22.04

As Ubuntu users, we may want to know if we are the only ones using our network, especially the WLAN, or if there are other unwanted users exploiting our network bandwidth. This capability and knowledge are also helpful when we want to be sure that no hacker is accessing our system by connecting to our network.

Scan your network with Nmap on Ubuntu

This article describes step by step how to use the Nmap tool, which provides you with a list of all devices connected to your network. We have run the commands and procedures described in this article on Ubuntu 22.04 LTS.

Step 1: Open the Ubuntu command line

We will be using the Ubuntu command line, the Terminal, in order to view the devices connected to our network. Open the Terminal either through the system Dash or the Ctrl+Alt+T shortcut.

Step 2: Install the network scanning tool Nmap

When it comes to reliable network scanning, Nmap is a tool that you can totally depend on.

Enter the following command as sudo in the Terminal application in order to install the tool.

The system will ask you for the password for sudo since only an authorized user can install/uninstall and configure software on Ubuntu.

The system will also ask you to confirm the installation with y/n. Please type y and press enter to start the installation process.

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

To know which devices are connected to your network, you first need to determine the IP range or subnet mask of your network. We will use the ifconfig command to determine this IP. To run the ifconfig command, we need to install the net-tools package on our Ubuntu server or desktop. Use the following command to install net-tools if you do not already have it installed on your system:

$ sudo apt install net-tools

The system will prompt you with a y/n option to confirm the installation. Please enter Y and hit enter to begin the installation process.

Once you have the net-tools utility available, run the following command to get information about the network(s) your system is connected to:

The highlighted IP in the output shows that our system uses the subnet mask 192.168.100.0, and the range is 255. So our network IP range is from 192.168.100.0 to 192.168.100.255.

Alternative Installation via Ubuntu GUI

Instead of using the ifconfig tool, you can also get the subnet mask from the Ubuntu user interface.

Access the settings utility in System Dash and check the details of your network by clicking on the settings icon next to the WLAN or Ethernet network you are connected to.

In this example, we have checked the settings of a wi-fi network we are currently connected to.

The highlighted ipv4 address or the Default Route address indicates that we are connected to a subnet IP 192.168.100.0

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

Through the Nmap tool, you can scan the report of all devices connected to a network by providing the subnet mask IP as follows:

The output shows that three devices are connected to the network: the router itself, the Linux system I use on my laptop, and my phone.

Step 5: Exit the terminal

Use the following command to exit the terminal application after extracting the information you need:

In this article, you learned how an Ubuntu user could install and use the Nmap command. We showed you how to see which devices are connected to your network. This way, you can verify that no unauthorized device is connected to your network.

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