Linux scan wifi terminal

Scan for wifi Network

There are a multitude of fine, graphical wireless network configuration programs available to the Ubuntu community. However, there may come a day when you need to acquire a wireless connection from an unknown network on a strange network card from the recovery console. Or perhaps you just want to know how to connect to your home network from the command line. Either way, this HOWTO is for you.

This guide assumes that the drivers for your network card are properly set up. Otherwise, it would be too complicated to cover all vendors and chipsets.

Find Network Interface Card

Figure out the name of the interface for your wireless card

The interface name of cards for different vendors may be different, which is why this step is needed:

This will list the interface names for all NICs on your computer. It will probably include eth0 (hardwired NIC), lo (loopback interface for the localhost), and something for your wireless card (like wifi0, or wlan0).

For these steps let’s call whatever name you find for your wireless NIC [wifi interface].

If you have multiple wireless cards, all of them will be listed. To be sure that the interface that you select is a wireless interface, you can check that its directory contains a «wireless» folder:

cd /sys/class/net/[wifi interface]/wireless/

Release network connections

Just to be sure it’s not being used, bring your interface down, release your DHCP connection and then put it back up:

sudo ip link set dev [wifi interface] down sudo dhclient -r [wifi interface] sudo ip link set dev [wifi interface] up

Many of these commands require superuser priviledges (i.e. root access), so the sudo command precedes them. Of course, you could always use «sudo -s» or some other method to login to a shell as the root account, but why complicate matters?

Scan

sudo iwlist [wifi interface] scan

Note: In tests this command only worked with Atheros cards.

This should return results that look something like this:

wlan0 Scan completed : Cell 01 - Address: 00:04:E2:D0:D1:96 ESSID:"SMC" Mode:Master Channel:6 Frequency:2.437 GHz Quality=78/100 Signal level=-56 dBm Noise level=-127 dBm Encryption key:off Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s 9 Mb/s; 12 Mb/s; 18 Mb/s; 24 Mb/s; 36 Mb/s 48 Mb/s; 54 Mb/s Extra:tsf=00000039cdb32ac3

The ESSID, Frequency and Address are the most important labels here (quality may also factor into your decision, too. higher is better).

Setup Network Interface Card

Set the wireless NIC so that it will connect to the found wireless network:

sudo iwconfig [wifi interface] ap [whatever you found for the MAC address] sudo iwconfig [wifi interface] essid [whatever you found for essid] sudo iwconfig [wifi interface] freq [whatever you found for frequency]G

Note the «G» after the frequency, to denote «GHz».

Acquire Network Address

Acquire a DHCP address from your wireless router:

sudo dhclient [wifi interface]

Okay. assuming that your DHCP address was acquired properly, you should have a internet connection all set up. Now, this is probably too complicated of a process to do by hand, but there are a number of ways to automate it. That’s outside the scope of this tutorial!

Compatible Chipsets

It has become apparent that not all wireless interface cards work with the scan command. Can you add your results to the table below.

Command to find the manufacture and model of your pci card is:

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How to scan Wifi network from terminal in Linux

Scanning for wifi networks will show you the ssids of all the wifi networks in your neighbourhood that your wifi adapter can detect or connect to. By default the gui network manager apps do this in kde and gnome desktop environments.

However you can also scan the wifi networks from the command prompt. In this article we take a look at some simple commands that can be used to list out all the wifi networks that can be seen by the wifi adapter.

1. iwlist

The iwlist command when run with root privileges can scan and list out the wifi networks. Using grep we can extract the specific piece of information we are interested in. Here is a minimal example:

$ sudo iwlist wlp0s20f3 scan | grep -i 'frequency\|ssid\|signal' Frequency:2.442 GHz (Channel 7) Quality=36/70 Signal level=-74 dBm ESSID:"AirtelFiber" Frequency:2.412 GHz (Channel 1) Quality=43/70 Signal level=-67 dBm ESSID:"TP-Link_6018" Frequency:2.422 GHz (Channel 3) Quality=33/70 Signal level=-77 dBm ESSID:"Himadri" Frequency:2.432 GHz (Channel 5) Quality=31/70 Signal level=-79 dBm ESSID:"dlink-15A3" Frequency:2.437 GHz (Channel 6) Quality=30/70 Signal level=-80 dBm ESSID:"OnePlus 5" Frequency:2.447 GHz (Channel 8) Quality=33/70 Signal level=-77 dBm ESSID:"Krishna" Frequency:2.457 GHz (Channel 10) Quality=29/70 Signal level=-81 dBm ESSID:"JioFiber-01" Frequency:2.462 GHz (Channel 11) Quality=25/70 Signal level=-85 dBm ESSID:"Ayush22" Frequency:5.18 GHz (Channel 36) Quality=22/70 Signal level=-88 dBm ESSID:"Ayush22_5G" Frequency:5.22 GHz (Channel 44) Quality=24/70 Signal level=-86 dBm ESSID:"Himadri_5G" Frequency:2.417 GHz (Channel 2) Quality=33/70 Signal level=-77 dBm ESSID:"deep wifi" Frequency:2.452 GHz (Channel 9) Quality=23/70 Signal level=-87 dBm ESSID:"Subash_ext" Frequency:2.462 GHz (Channel 11) Quality=22/70 Signal level=-88 dBm ESSID:"angshu" Frequency:5.745 GHz Quality=26/70 Signal level=-84 dBm ESSID:"AirtelFiber_5GHz" $

You need to specify the interface name of your wifi adapter. If you don’t already know that use the iwconfig command to find it.

Note that it is important to run the command with root privileges. Without root the command will run but the output will not be accurate and keep changing everytime.

We can see the ssid, signal level, frequency band and channel number of each wifi network. This is useful information!

2. iw command

The next command is iw and it can scan the wifi networks as well.

$ sudo iw dev wlp0s20f3 scan | grep -i 'ssid\|signal\|^bss' BSS 98:35:ed:d4:e1:48(on wlp0s20f3) -- associated signal: -66.00 dBm SSID: AirtelFiber BSS ac:84:c6:f4:60:18(on wlp0s20f3) signal: -62.00 dBm SSID: TP-Link_6018 BSS b6:a7:c6:53:cf:00(on wlp0s20f3) signal: -79.00 dBm SSID: BSS b4:a7:c6:53:cf:00(on wlp0s20f3) signal: -80.00 dBm SSID: Himadri HESSID: 00:00:00:00:00:00 BSS b4:b0:24:3f:29:44(on wlp0s20f3) signal: -79.00 dBm SSID: deep wifi BSS 8c:a3:99:d3:79:f3(on wlp0s20f3) signal: -83.00 dBm SSID: JioFiber-01 BSS 98:35:ed:d4:e1:4c(on wlp0s20f3) signal: -82.00 dBm SSID: AirtelFiber_5GHz BSS b4:a7:c6:53:cf:01(on wlp0s20f3) signal: -85.00 dBm SSID: Himadri_5G BSS b6:a7:c6:53:cf:01(on wlp0s20f3) signal: -84.00 dBm SSID: BSS 8c:a3:99:2f:a9:fd(on wlp0s20f3) signal: -84.00 dBm SSID: Ayush22_5G BSS 0c:80:63:76:5f:90(on wlp0s20f3) signal: -79.00 dBm SSID: Krishna BSS 7a:22:e5:f1:83:6d(on wlp0s20f3) signal: -83.00 dBm SSID: OnePlus 5 $

The output has lots of information quite similar to the iwlist command.

3. nmcli command

The nmcli command is actually a tool to control NetworkManager from the terminal. And it can used to query the interface for available wifi networks. Here is a quick example.

Note that we need not provide the interface name of the wifi adapter with nmcli.

$ nmcli dev wifi list IN-USE BSSID SSID MODE CHAN RATE SIGNAL BARS SECURITY AC:84:C6:F4:60:18 TP-Link_6018 Infra 1 270 Mbit/s 64 ▂▄▆_ WPA2 * 98:35:ED:D4:E1:48 AirtelFiber Infra 7 130 Mbit/s 53 ▂▄__ WPA2 B4:B0:24:3F:29:44 deep wifi Infra 2 270 Mbit/s 39 ▂▄__ WPA2 B4:A7:C6:53:CF:00 Himadri Infra 3 130 Mbit/s 39 ▂▄__ WPA2 60:63:4C:84:15:AA dlink-15A3 Infra 5 270 Mbit/s 35 ▂▄__ WPA1 WPA2 8C:A3:99:D3:79:F3 JioFiber-01 Infra 10 130 Mbit/s 34 ▂▄__ WPA2 0C:80:63:76:5F:90 Krishna Infra 8 405 Mbit/s 32 ▂▄__ WPA2 8C:A3:99:2F:A9:FC Ayush22 Infra 11 130 Mbit/s 29 ▂___ WPA2 8A:D8:1B:26:FC:02 -- Infra 9 195 Mbit/s 27 ▂___ WPA2 8C:A3:99:2F:A9:FD Ayush22_5G Infra 36 270 Mbit/s 27 ▂___ WPA2 B6:A7:C6:53:CF:01 -- Infra 44 270 Mbit/s 27 ▂___ WPA2 98:35:ED:D4:E1:4C AirtelFiber_5GHz Infra 149 270 Mbit/s 27 ▂___ WPA2 10:62:EB:1D:D2:F5 Debnath_Adv2 Infra 1 270 Mbit/s 25 ▂___ WPA1 WPA2 7A:22:E5:F1:83:6D OnePlus 5 Infra 6 130 Mbit/s 25 ▂___ WPA2 B4:A7:C6:53:CF:01 Himadri_5G Infra 44 270 Mbit/s 24 ▂___ WPA2 84:D8:1B:26:FC:02 Subash_ext Infra 9 195 Mbit/s 22 ▂___ WPA1 WPA2 84:D8:1B:14:9F:D0 Joydip Infra 10 270 Mbit/s 22 ▂___ WPA2 60:E3:27:7B:2B:D4 angshu Infra 11 135 Mbit/s 20 ▂___ WPA2 $

The nmcli command generates a fancy colorful output with a nice looking signal strength bar graph. The output is quite well formatted also.

Conclusion

That was a quick list of commands to query wifi networks from the command shell. If you want to learn more about wifi commands in linux check out our previous articles.

A Tech Enthusiast, Blogger, Linux Fan and a Software Developer. Writes about Computer hardware, Linux and Open Source software and coding in Python, Php and Javascript. He can be reached at [email protected] .

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How to Scan for (& Connect to) Wifi Access Points from Command Line in Linux

This is a beginner’s guide shows how to scan for wireless access points in Linux from command line.

NetworkManager has a built-in command-line interface called nmcli. With nmcli, you can create, display, edit, delete, activate, and deactivate network connections, as well as control and display network device status.

Supported Linux systems:

As the command line interface for NetworkManager, it should work on most Linux systems including Ubuntu, Debian, Fedora, and more.

Command to list wireless access points:

To scan for Wi-Fi access points, simply open terminal and run command:

It will output a list of APs with information including BSSID, SSID, MODE, CHANNEL, SIGNAL, and more. Just as the top feature image shows.

Connect to a Wi-Fi AP via Linux command:

Simply run the command below in terminal will connect to a specified Wifi AP:

nmcli --ask device wifi connect "SSID_HERE"

with —ask flag, it asks for password before connection.

You can also type the password within the command, so it will be:

nmcli device wifi connect "SSID_HERE" password "PASSWORD_HERE"

And it will prompt that your Wi-Fi device activated successfully once connected.

Other nmcli commands:

The powerful command line tool can do many other useful things including:

Toggle on or off networking via command:

It can also tell the current Wi-Fi connection password along with a QR code for sharing with friends.

For more about the tool, run man nmcli in terminal and enjoy!

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