Shulou(Shulou.com)06/02 Report--

preface

One of the most common tasks we do after installing a Linux system is network configuration. Of course, you can configure the network interface when installing the system. However, for some people, they prefer to configure the network or change existing settings after installing the system.

It is well known that in order to configure network settings from the command line, we must first know how many network interfaces are available in the system. This simple guide will list all possible ways to find network interfaces available on Linux and Unix operating systems.

Find network interfaces available in Linux

We can use the following methods to find available network interfaces.

Method 1 Using the ifconfig command

Using the ifconfig command to view network interfaces remains the most common method. I believe there are still many Linux users who still use this method.

$ ifconfig -a

Example output:

enp5s0: flags=4098 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 mtu 65536

inet 127.0.0.1 netmask 255.0.0.0

inet6 ::1 prefixlen 128 scopeid 0x10

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 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

inet6 fe80::c218:85ff:fe50:474f prefixlen 64 scopeid 0x20

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 the output above shows, there are two network interfaces on my Linux machine called enp 5s0 (wired on motherboard) and wlp 9s0 (wireless). lo is a loopback network card used to access local network services, usually with IP address 127.0.0.1.

We can also use the same ifconfig in many UNIX variants such as FreeBSD to list available network cards.

Method 2 Using the ip command

The ifconfig command has been deprecated in recent Linux releases. You can list network interfaces using the ip command, as follows:

$ ip link show

Example output:

1: lo: 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: 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: 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

You can also use the following command to view it.

$ ip addr$ ip -s link

Did you notice that? These commands also show the status of the connected network interfaces. If you look closely at the output above, you'll notice that my wired NIC isn't connected to the network cable (see DOWN in the output above). Also, my wireless card is already connected (see UP in the output above). For more details, check out our previous guide on viewing the connected state of network interfaces in Linux.

These two commands (ifconfig and ip) are enough to check the available network cards in your LInux system.

However, there are still other ways to list network interfaces in Linux, which we'll see below.

Method 3 Using the/sys/class/net directory

The Linux kernel stores details of network interfaces in the/sys/class/net directory, and you can verify that the list of available interfaces matches the previous results by looking at the contents of this directory.

$ ls /sys/class/net

Example output:

enp5s0 lo wlp9s0

Method 4 Using the/proc/net/dev directory

On Linux, the file/proc/net/dev contains information about network interfaces.

To view the available network cards, simply use the following command to view the contents of the file above:

$ cat /proc/net/dev

Example 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 the netstat command

The netstat command lists various information such as network connections, routing tables, interface statistics, masquerade connections, and multicast membership.

$ netstat -i

Example 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

Note that netstat has been deprecated, and the replacement command for netstat -i is ip -s link. Also note that this method lists only active interfaces, not all available interfaces.

Method 6 Using the nmgli command

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

If NetworkManager is installed on your Linux system, you can use nmgli to list the network interfaces available using the following command:

$ nmcli device status

or

$ nmcli connection show

Now you know how to find available network interfaces in Linux

If you know of any other quick ways to find network interfaces available in Linux, please share them in the comments section below and I'll check your comments and update this guide.

summary

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