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Find Available Network Interfaces On Linux

How To Find Available Network Interfaces On Linux

By sk
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One of the common task we do after installing a Linux system is network configuration. Of course, you can configure network interfaces during the installation time. But, some of you might prefer to do it after installation or change the existing settings. As you know already, you must first know how many interfaces are available on the system in-order to configure network settings from command line. This brief tutorial addresses all the possible ways to find available network interfaces on Linux and Unix operating systems.

Find Available Network Interfaces On Linux

We can find the available network cards in couple ways.

Method 1 - Using 'ifconfig' Command:

The most commonly used method to find the network interface details is using 'ifconfig' command. I believe some of Linux users might still use this.

$ ifconfig -a

Sample output:

enp5s0: flags=4098<BROADCAST,MULTICAST> mtu 1500
ether 24:b6:fd:37:8b:29 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 1000 (Local Loopback)
RX packets 171420 bytes 303980988 (289.8 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 171420 bytes 303980988 (289.8 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

wlp9s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.225.37 netmask 255.255.255.0 broadcast 192.168.225.255
inet6 2409:4072:6183:c604:c218:85ff:fe50:474f prefixlen 64 scopeid 0x0<global>
inet6 fe80::c218:85ff:fe50:474f prefixlen 64 scopeid 0x20<link>
ether c0:18:85:50:47:4f txqueuelen 1000 (Ethernet)
RX packets 564574 bytes 628671925 (599.5 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 299706 bytes 60535732 (57.7 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

As you see in the above output, I have two network interfaces namely enp5s0 (on board wired ethernet adapter) and wlp9s0 (wireless network adapter) on my Linux box. Here, lo is loopback interface, which is used to access all network services locally. It has an ip address of 127.0.0.1.

We can also use the same 'ifconfig' command in many UNIX variants, for example FreeBSD, to list available network cards.

Method 2 - Using 'ip' Command:

The 'ifconfig' command is deprecated in the latest Linux versions. So you can use 'ip' command to display the network interfaces as shown below.

$ ip link show

Sample output:

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
   link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: enp5s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
    link/ether 24:b6:fd:37:8b:29 brd ff:ff:ff:ff:ff:ff
3: wlp9s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DORMANT group default qlen 1000
    link/ether c0:18:85:50:47:4f brd ff:ff:ff:ff:ff:ff
ip command

Find Available Network Interfaces Using 'ip' Command On Linux

You can also use the following commands as well.

$ ip addr
$ ip -s link

Did you notice that these command also shows the connected state of the network interfaces? If you closely look at the above output, you will notice that my Ethernet card is not connected with network cable (see the word "DOWN" in the above output). And wireless network card is connected (See the word "UP"). For more details, check our previous guide to find the connected state of network interfaces on Linux.

These two commands (ifconfig and ip) are just enough to find the available network cards on your Linux systems.

However, there are few other methods available to list network interfaces on Linux. Here you go.

Method 3:

The Linux Kernel saves the network interface details inside /sys/class/net directory. You can verify the list of available interfaces by looking into this directory.

$ ls /sys/class/net

Output:

enp5s0 lo wlp9s0

Method 4:

In Linux operating systems, /proc/net/dev file contains statistics about network interfaces.

To view the available network cards, just view its contents using command:

$ cat /proc/net/dev

Output:

Inter-| Receive | Transmit
face |bytes packets errs drop fifo frame compressed multicast|bytes packets errs drop fifo colls carrier compressed
wlp9s0: 629189631 566078 0 0 0 0 0 0 60822472 300922 0 0 0 0 0 0
enp5s0: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
lo: 303980988 171420 0 0 0 0 0 0 303980988 171420 0 0 0 0 0 0

Method 5: Using 'netstat' command

The netstat command displays various details such as network connections, routing tables, interface statistics, masquerade connections, and multicast memberships.

$ netstat -i

Sample output:

Kernel Interface table
Iface MTU RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg
lo 65536 171420 0 0 0 171420 0 0 0 LRU
wlp9s0 1500 565625 0 0 0 300543 0 0 0 BMRU

Please be mindful that netstat is obsolete. The Replacement for "netstat -i" is "ip -s link". Also note that this method will list only the active interfaces, not all available interfaces.

Method 6: Using 'nmcli' command

The nmcli is nmcli is a command-line tool for controlling NetworkManager and reporting network status. It is used to create, display, edit, delete, activate, and deactivate network connections and display network status.

If you have Linux system with Network Manager installed, you can list the available network interfaces using nmcli tool using the following commands:

$ nmcli device status

Or,

$ nmcli connection show

You know now how to find the available network interfaces on Linux. Next, check the following guides to know how to configure IP address on Linux.

If you know any other quick ways to do it, please share them in the comment section below. I will check and update the guide with your inputs.

And, that's all.  More good stuffs to come. Stay tuned!

Cheers!

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2 comments

01101001b March 5, 2019 - 2:17 am

Very interesting article! Thank you!

As a matter of fact, I find it difficult to understand why good tools like netstat and ifconfig are deemed “outdated” or “deprecated” if they work well even today. I don’t reject new tools, even if they do something quite similar to existing ones, but if something is obsolete, it’ll disappear by itself.

Change is ok. But to change something just because, for the change in itself, sounds much like Wind*ws users’ mentality to me. New? Old? What matters? The important thing is the tool is still useful. Just my two cents. Regards!

Reply
sk March 5, 2019 - 12:15 pm

Completely agree with your point. I still use some of the deprecated tools, like ifconfig and netstat. Old habits die hard.

Reply

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